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The input voltage can range from about 5 to 24 V. Using a flyback from a MAC
Plus computer which had its bad primary winding excised, an output of more than
20 kV was possible (though risky since the flyback is probably not rated for
more than about 12 kV) from a 24 VDC, 2 A power supply. By adjusting the drive
frequency and duty cycle, a wide range of output voltages and currents may
be obtained depending on your load.
With the addition of a high voltage filter capacitor (0.08 uF, 12 kV), this
becomes a nice little helium neon laser power supply which operates on 8 to
15 VDC depending on required tube current and ballast resistor. See the
document: Sam's Laser
FAQ.
The transistor types are not critical. Those were selected basically because
I had them in my junk box. A TV or monitor horizontal output transistor (HOT)
should be satisfactory for the chopper but will require good strong drive.
The lower voltage, high current transistor I used (2SD797) has both a higher
current and higher Hfe rating than typical HOTs. Even a 2N3055 will probably
survive and not be too bad in the performance department.
The drive transformer is from a B/W computer monitor (actually a video display
terminal) and has a turns ratio of 4:1 wound on a 5/16" square by 3/8" long
nylon bobbin on a gapped ferrite double E core. The primary has 80 turns and
the secondary has 20 turns, both of #30 wire. Make sure you get the polarity
correct: The base of the switching transistor should be driven when the driver
turns on. You should be able to wind a transformer similar to this in about
10 minutes if a similar size (doesn't need to be exact) core is available.
Where the flyback includes an internal rectifier and/or you are attempting
to obtain the maximum output voltage of a specific polarity, the direction of
drive matters as the largest pulse amplitude is generated when the switching
transistor turns off. Since flyback transformers are not marked, you will
have to try both possible connections to the drive coil. Use the one that
produces the higher output voltage for a given set of input conditions (drive
and pulse rate/width).
Many variations on this basic circuit are certainly possible. The dual 555
circuit can be reduced to a single 555 with some loss in flexibility (unless
you use the cute non-standard modification that allow independent adjustment
of the high and low times - left as an exercise for the student).
One nice thing about running it at 24 VDC or less (as opposed to line
voltage) is that it is much more difficult to let the smoke out of th
circuit! The 5 A power supply I was using shut down on several occasions
due to overcurrent but the only time I blew the chopper transistor was by
accidentally shorting the base to collector.
Evertron Model 3210 Gas Tube Power Supply is
the schematic of an inverter type unit for driving a neon sign. It has a pair
of power MOSFETs driving a flyback style high voltage transformer, with a
whole bunch of open-wound primaries and a potted secondary.
The adjustments on each section are for the current limit, not output voltage
as might be expected. The output voltage for each section is set by fixed
resistors (one of which is inside the potted HV module).
It would be a simple matter to replace R12 or R32 to vary the C or T
output voltages within a modest range (like 4 to 6 kV). But going
too high is asking for smoke. :) If pots are used, make sure their
maximum value will limit the output voltage to something reasonable.
Many modern gas stoves, ovens, furnaces, and other similar appliances use an
electronic ignition rather than a continuously burning pilot flame to ignite
the fuel. These are actually simple high voltage pulse generators.
The high-tech versions consist of a high voltage low current power supply and
fluorescent (usually) lamp selected to attract undesirable flying creatures.
(Boring low-tech devices may just use a fan to direct the insects to a tray of
water from which they are too stupid to be able to excape!)
However, these devices are not selective and will obliterate friendly and
useful bugs as well as unwanted pests.
Here is a typical circuit:
(From: Andrew Bowers (falcon_@geocities.com).)
This is from my friend's bug zapper:
This is your ultimate simple bug zapper -- no power switch, although the
metal plate that the transformer and other parts are mounted on is grounded.
This module produces both positive and negative outputs when connected to 115
VAC, 60 Hz line voltage. Each is about 5 kV at up to around 5 uA. It is
probably similar to the high voltage power supply in the AirEase(tm) Personal
Space Ionization Air Cleaner from Ion Systems, Inc., a small table top unit.
(Unfortunately, the HV module in the AirEase was totally potted so I could not
determine anything about its internal circuitry.)
The LED (IL1) is a power-on indicator. :-)
The transformer was totally potted so I could not easily determine anything
about its construction other than its winding resistances and turns ratio
(about 1:100).
From my measurements, this circuit produces a total of around 10 kV between
HV+ and HV-, at up to 5 uA. The output voltages are roughly equal plus and
minus when referenced to point B.
I assume the module would also operate on DC (say, 110 to 150 V) with the
discharges repeating continuously at about 2 kHz. Output current capability
would be about 5 times greater but at the same maximum (no load) voltage.
(However, with DC, if the SCR ever got stuck in an 'on' state, it would be
stuck there since there would be no AC zero crossings to force it off. This
wouldn't be good!)
The secondary side circuitry can be easily modified or redesigned to provide
a single positive or negative output or for higher or lower total voltage.
Simply removing R4 will isolate it from the input and earth ground (assuming
T1's insulation is adequate).
Where there is no high voltage from such a device, check the following:
DL1 to DL4 look like neon light bulbs with a single electrode. They glow like
neon light bulbs when the circuit is powered and seem to capacitively couple
the HV pulses to the grounded grid in such a way to generate ozone. I don't
know if they are filled with special gas or are just weird neon light bulbs.
An ultrasonic cleaner contains a power oscillator driving a large piezoelectric
transducer under the cleaning tank. Depending on capacity, these can be quite
massive.
A typical circuit is shown below. This is from a Branson Model 41-4000 which
is typical of a small consumer grade unit. The H and N are Hot and Neutral
of the 115 VAC line. WARNING: Line connected input. Use isolation
transformer for safety when troubleshooting.
The power transistor (Q1) and its associated components form an self excited
driver for the piezo-transducer (PT1). I do not have specs on Q1 but based on
the circuit, it probably has a Vceo rating of at least 500 V and power rating
of at least 50 W.
Two windings on the transformer (T1, which is wound on a toroidal ferrite
core) provide drive (D) and feedback (F) respectively. L1 along with the
inherent capacitance of PT1 tunes the output circuit for maximum amplitude.
The output of this (and similar units) are bursts of high frequency (10s to
100s of kHz) acoustic waves at a 60 Hz repetition rate. The characteristic
sound these ultrasonic cleaners make during operation is due to the effects
of the bursts occuring at 60 Hz since you cannot actually hear the ultrasonic
frequencies they use.
The frequency of the ultrasound is approximately 80 kHz for this unit with a
maximum amplitude of about 460 VAC RMS (1,300 V p-p) for a 115 VAC input.
WARNING: Do not run the device with an empty tank since it expects to have
a proper load. Do not touch the bottom of the tank and avoid putting your
paws into the cleaning solution while the power is on. I don't know what,
if any, long term effects there may be but it isn't worth taking chances.
The effects definitely feel strange. At high enough power levels, it could
indeed pulverize bones as described below. Whether that could happen with
the typical small ultrasonic cleaner, I don't know and am not about to find
out!
(From: BIll Perry (perry.williamr@tacamo.navy.mil).)
"While stationed on board the now-decommissioned submarine USS
Hawkbill (SSN-666), I pondered this as well. One of my senior shipmates
related a story of a sailor who had done that very act on his previous
submarine. The guy put his feet it the cleaner while it was powered on.
He remarked that it felt very good and relaxing. After a few minutes, he
pulled his feet out, and as soon as he stood up and applied his full bodily
weight on his feet, all the bones in his feet had shattered. He got
permanent disability from it. Apparently, it had rattled his bones apart.
Wow!"
Where the device doesn't oscillate (it appears as dead as a door-nail), first
check for obvious failures such as bad connections and cracked, scorched, or
obliterated parts.
To get inside probably requires removing the bottom cover (after pulling the
plug and disposing of the cleaning solution!).
CAUTION: Confirm that all large capacitors are discharged before touching
anything inside!
The semiconductors (Q1, D1, D2, D3) can be tested for shorts with a multimeter
(see the document:
Basic Testing of
Semiconductor Devices.
The transformer (T1) or inductor (L1) could have internal short circuits
preventing proper operation and/or blowing other parts due to excessive load
but this isn't kind of failure likely as you might think. However, where all
the other parts test good but the cleaning action appears weak without any
overheating, a L1 could be defective (open or other bad connections) detuning
the output circuit.
Where the transistor and/or fuse has blown, look for a visible burn mark on
the transducer and/or test it (after disconnecting) with a multimeter. If
there is a mark or your test shows anything less than infinite resistance,
there may have been punch-through of the dielectric between the two plates.
I don't know whether this could be caused by running the unit with nothing in
the tank but it might be possible. If the damage is localized, you may be able
to isolate the area of the hole by removing the metal electrode layer
surrounding it to provide an insulating region 1/4 inch in diameter. This
will change the resonant frequency of the output circuit a small amount but
hopefully not enough to matter. You have nothing to lose since replacing the
transducer is likely not worth it (and perhaps not even possible since it is
probably solidly bonded to the bottom of the tank).
When testing, use a series light bulb to prevent the power transistor from
blowing should there be a short circuit somewhere (see the document:
Troubleshooting and
Repair of Consumer Electronic Equipment) AND do not run the unit with and
empty tank.
Also see the info on ultraonic humidifiers in the document:
Troubleshooting and Repair of Small Household
Appliances.
This is also the simplest and safest way to construct a small DC power supply
as you do not need to deal with the 110 VAC at all.
To convert such an adapter to DC requires the use of:
The basic circuit is shown below:
Therefore, you will need to find an AC wall adapter that produces an output
voltage which will result in something close to what you need. However,
this may be a bit more difficult than it sounds since the nameplate rating
of many wall adapters is not an accurate indication of what they actually
produce especially when lightly loaded. Measuring the output is best.
The following is a very basic introduction to the construction of a circuit
with appropriate modifications will work for outputs in the range of about
1.25 to 35 V and currents up 1 A. This can also be used as the basis for a
small general purpose power supply for use with electronics experiments.
What you want is an IC called an 'adjustable voltage regulator'. The LM317 is
one example - Radio Shack should have it along with a schematic. The LM317
looks like a power transistor but is a complete regulator on a chip.
Here is a sample circuit:
Here are pinouts for the most common types:
Note: Various manufacturers may label the pins differently than shown just to
be confusing. For example, 1,3,2 instead of 1,2,3. However, the location of
each pin will be the same so double check with the diagram.
For the LM317:
However, note that a typical adapter's voltage may vary quite a bit
depending on manufacturer and load. You will have to select one that
isn't too much greater than what you really want since this will add
unnecessary wasted power in the device and additional heat dissipation.
Using 10,000 uF per *amp* of output current will result in less than 1 V
p-p ripple on the input to the regulator. As long as the input is always
greater than your desired output voltage plus 2.5 V, the regulator will
totally remove this ripple resulting in a constant DC output independent
of line voltage and load current fluctuations. (For you purists, the
regulator isn't quite perfect but is good enough for most applications.)
Make sure you select a capacitor with a voltage rating at least 25% greater
than the adapter's *unloaded* peak output voltage and observe the polarity!
Note: wall adapters designed as battery chargers may not have any filter
capacitors so this will definitely be needed with this type. Quick check:
If the voltage on the adapter's output drops to zero as soon as it is pulled
from the wall - even with no load - it does not have a filter capacitor.
For an unregulated supply, take the outputs from V+ and V-.
Here is a circuit for a +/- 12 VDC supply:
Since only half-wave rectification is used, the main filter caps, C1 and C2,
should be at least twice the uF value compared to full wave or bridge circuits
to obtain the same ripple.
Another disadvantage of this configuration is that if the currents drawn from
the outputs aren't equal, net DC flows through the transformer secondary
(with a voltage doubler having no output connection to the common point,
this isn't possible). Core saturation may result if operating near the
transformer's maximum current ratings.
For a negative supply based on a 79xx regulator, use an NPN transistor like
a 2N3055 and reverse the capacitor polarities. Don't forget that the pinout
for the 79xx and other negative voltage regulators is NOT the same as for
the positive variety. See the section: Adding an IC
Regulator to a Wall Adapter or Battery.
* For proper regulation, RL must be low enough in value to guarantee at least a
30 mA current at the selected output voltage. It can be a separate resistor
or part of the actual load.
For even higher current operation, multiple power transistors (Q2) can be
wired in parallel as a pass-bank with small (e.g., 0.1 ohm) emitter resistors
to balance the load. In this case, Q1 may need to be a slightly bigger
transistor and R4 reduced in value to provide adequate base drive. Details
will depend on your particular needs.
As with the other circuits, a negative power supply can be constructed by
using the appropriate regulator IC, swapping NPN or PNP transistors, and
reversing all the polarities of the capacitors and diode.
(From: David Subert (voodoo2daddy@yahoo.com).)
As it turns out, the bipolar transistors can be replaced by IRF9630 MOSFETS.
The only other modification required is to change the value of the 5 ohm
resistor in order to properly bias the MOSFET. This is significant because
MOSFETs can be easily arranged in parallel without having to worry about the
inconsistent BETA of parallel BJTs.
D1 to D4 can be individual diodes or a bridge rated for at least 3 A.
The regulator (IC1) is an LT1084CP which is similar to an LM317 but is a low
dropout type rated at 5 A max. I had a pile of these left over from a certain
multi-million dollar project that had been cancelled due to upper management
foot in a** disease..... An external pass transistor may be needed to use
an LM317 because of the peak current requirement.
Despite the transformer only being rated for 1 A, with IC1 on a modest
heatsink, the supply seems perfectly happy putting out 3 A at 1.5 V for an
extended period. I don't know that I would run it all day at this high
current but for my purposes, it seems fine.
It turns out that the typical electronic flash circuit from a disposable
camera like the Kodak MAX (see Schematic and
Photo), actually draws more
than 3 A at the start of its recharge cycle. So, the voltage does dip a
bit but this doesn't affect much of anything. Recharge time with the power
supply is at least as rapid as with a fresh Alkaline cell. The voltage from
an Alkaline cell also dips a bit under these conditions.
Obviously, the circuit could be easily modified to put out 2.4 VDC (for a pair
of NiCd cells), 3 VDC (for two Alkalines), or whatever else you might need.
Here is a cute circuit that gets around both these problems. The original
article is from George Hrischenko but the link no longer works.
The output voltage is approximately 2.8 times the RMS rating of the
transformer secondary (primary not shown). Ripple is at 2X the power
line frequency.
Obviously, other voltages than +12 VDC can be produced in this manner - the
example was a coincidence.
This could also be done with fewer components using modern SMPS ICs designed
DC-DC converter applications but I don't have any suggestions off-hand.
Errors in transcription are possible. Some models use additional outputs each
fed from a single rectifier diode and filter capacitor (not shown). Some part
numbers and the connector pinout may not be the same for your particular VCR.
A totally dead supply with a blown fuse usually means a shorted switchmode
power transistor, Q1. Check all other components before applying power
after replacement as other parts may be bad as well.
The most common problems resulting in low or incorrect outputs are dried
up or leaky electrolytic capacitors - C4, C16, C17, C21.
See the document:
Notes on the
Troubleshooting and Repair of Small Switchmode Power Supplies for more
info.
The AC line input and degauss components are at the upper left, the SMPS
chopper, its controller, and feedback opto-isolator are in the lower
left/middle, and the secondaries - some with additional regulation components -
occupy the entire right side of this diagram. Even for relatively basic
application such as this, the circuitry is quite complex. There are more than
a half dozen separate outputs regulated in at least 3 different ways!
The variable voltage B+ regulator is in the upper right corner. This provides
an voltage to power the horizontal deflection which is determined by the
video input. To maintain the same picture width, the required voltage to the
horizontal output transistor/flyback needs to be roughly proportional to
horizontal scan rate.
However, the circuit described in the section: Super Simple
Inverter only requires off-the-shelf components but has a pitiful
efficiency. But construction is, well, super simple :-).
And, it should be easy to make modifications to the flash units from pocket
or disposable cameras as described in the section: Up to 350
VDC Inverter from 1.5 V Alkaline Cell since these are quite readily
available for free if you know where to ask!
For more information on fluorescent and xenon lamps, see the documents:
Fluorescent Lamps,
Ballasts, and Fixtures and
Notes on the
Troubleshooting and Repair of Electronic Flash Units and Strobe Lights and
Design Guidelines, Useful Circuits, and Schematics, respectively.
Output depends on input voltage. Adjust for your application. With the
component values given, it will generate over 400 V from a 12 V supply and
charge a 200 uF capacitor to 300 V in under 5 seconds.
For your less intense applications, a fluorescent lamp can be powered directly
from the secondary (without any other components). This works reasonably well
with a F13-T5 or F15-T12 bulb (but don't expect super brightness). Q1 does
get quite hot so use a good heat sink.
The AmerTac Fluorescent Lamp Ballast is from a
portable 12 V light made in China for American Tack & Hardware Co sold in Home
Depot stores. It burned out after about 30 minutes of continuous use. (OK,
maybe you shouldn't consider duplicating this exactly! --- Sam) So I decided
to take it apart and see what was in there.
What it had was a very small circuit board (about 1/2" x 2"). Both the
transformer and the transistor were melted beyond recognition. The
transformer was apparently custom made out of two 'E' cores taped together.
I have another identical unit, so I could read the transistor part number:
2SD882. It is rated 80 V, 5 A, 40 W, typical Hfe of 30, in a TO127 package.
Unlike many of the others, this circuit powers both both filaments in the tube
but is otherwise very similar.
I have another identical unit which hasn't been fried so I put a UV bulb in
there and fired it up. It is clear that only one end has a glowing filament.
It is the end connected to pins 5 & 6 of the transformer. The filament
attached to pins 1 and 2 appears to only work as a resistor. The circuit will
not operate without the bulb so I wasn't able to get reliable readings.
This design can easily be modified for many other uses at lower or higher
power.
The 315T O (Output) is wound first followed by the 28T D (Drive) and 28T F
(Feedback) windings. There should be a strip of mylar insulating tape
between each of the windings.
The number of turns were estimated without disassembly as follows:
Since it is very low power, no heat sink is used in the Archer flashlight.
However, for other applications, one may be needed.
This design is very similar to the Archer model (see the section:
Archer Mini Flashlight Fluorescent Lamp Inverter, but
eases starting requirements by actually heating one of the filaments of the T5
lamp. Thus, a lower voltage transformer can be used.
The 160T O (Output) is wound first followed by the 16T H (Heater), 32T D
(Drive), and 16 T F (Feedback) windings. There should be a strip of mylar
insulating tape between each of the windings.
The number of turns were estimated after unsoldering the transformer from
the circuit board as follows:
Since it is very low power, no heat sink is used in the Energizer
flashlight. However, for other applications, one may be needed.
This was reverse engineered from a toy pocket blacklight, made in China.
It has been tested with tubes up to 6 W.
Here's another schematic from a little light stick intended for use in a car
at 12 V. It uses an F8T5 bulb and is quite similar to the Archer inverter
(A HREF="#schamf">Archer Mini Flashlight Fluorescent Lamp Inverter
All Rights Reserved
2.There is no charge except to cover the costs of copying.
DISCLAIMER
Many of the circuits have been reverse engineered - traced from various
schematics or actual hardware. There may be errors in transcription,
interpretation, analysis, or voltage or current values listed. They are
provided solely as the basis for your own designs and are not guaranteed to be
'plans' that will work for your needs without some tweaking.
Introduction
Scope of This Document
This is a collection of various useful and interesting schematics. Some
of these are also referenced by or included in other documents at this site.
Some are my own designs while many have been reverse engineered from commercial
equipment. Many are the sorts of circuits you won't find in any textbook or
in any other readily available on-line or print media. Some are just cute. :)
Safety Considerations
Some of these circuits operate at extremely lethal voltage and current levels.
The energy storage capacitors in even the smallest disposable camera
flash operating from a 1.5 V AA battery can be deadly under the wrong
conditions. Line powered devices - including little ones - may have an added
danger of high power at high voltage AND are often non-isolated (no power
transformer). Do not attempt to troubleshoot, repair, or modify such equipment
without understanding and following ALL of the relevant safety guidelines for
high voltage and/or line connected electrical and electronic systems.
Related Information
Before thinking about experimenting with anything using or producing high
voltages or connected to the AC line - even opening up a disposable camera
that may have been laying around gathering dust (the capacitor can still be
charged - outch!), see the document: Safety Guidelines
for High Voltage and/or Line Powered Equipment. Something that looks
innocent can really ruin your entire day!
See the Home and Mirror Site Locations for other
possibilities which may be faster from where you live.
High Voltage Power Supplies
Simple High Voltage Generator
This basic circuit is capable of supplying up to 30 kilovolts or more
from a low voltage DC source using a flyback (LOPT) transformer salvaged
from a TV or computer monitor. Typical output with a 12 VDC 2 A power
supply or battery will be around 12,000 V. Current at full voltage is
typically around 1 to 2 mA. Higher currents are available but the output
voltage will drop. At 2 kV, more than 10 mA may be possible depending on
your particular flyback transformer.
Adjustable High Voltage Power Supply
This circuit uses a pair of 555 timers to provide variable frequency variable
pulse width drive to an inverter using a flyback transformer salvaged from
a black and white or color TV or computer monitor. At very
low repetition rates, it will produce individual sparks. At high rates with
a low uF value high voltage capacitor, the output will essentially be HV DC
with a specific value dependent on input voltage, pulse rate and width, and
load. None of the component values is critical. The particular transistor
used for Q2 seemed to be zappier better than a common horizontal output type
but they work as well.
Evertron Model 3210 Gas Tube Power Supply
(Thanks to Jeff Zurkow (jeff@atrox.com) for reverse engineering this device
and drawing the schematic.)
Ricoh 3E06-1 High Voltage Power Supply
This is the high voltage power supply for a Ricoh laser printer or copier
as shown in Photo of Ricoh Model 3E06-1 High Voltage
Power Supply. It has two negative outputs of -5.3 kVDC at 0.3 mA
max (output C) and -5.7 kVDC at 0.4 mA max (output T). I assume these stand
for something like "Corona" and "Transfer" based on their functions. The two
sections are independent with the only components in common being the power
connector and a filter capacitor. Each section is based on a TL494
PWM controller IC. This is the same one used in many/most PC power supplies.
A Web search will quickly locate a datasheet. Separate enable inputs permit
each voltage to be turned on individually. All the low voltage circuitry is
exposed with the high voltage circuitry being inside a module filled with red
goop. I have not yet ungooped it so the circuitry inside the potting is
essentially guessed at this point. The two sections are on separate
schematic pages which are virtually identical except for part numbers and
a few part values:
Jacobs Ladders
The climbing arcs of old bad sci-fi movies are always a popular item. Just
make sure you understand the safety implications before constructing one of
these. See the document: Safety Guidelines for High
Voltage and/or Line Powered Equipment.
Assorted High Voltage Circuits
Assorted High Voltage Circuits Introduction
These are assorted circuits which produce pulses or continuous high voltage
for various purposes around the house. There is also an ultrasonic cleaner
(sort of high voltage) here because it didn't seem to belong anywhere else. :-)
Range, Oven, and Furnace Electronic Ignition
The Harper-Wyman Model 6520 Kool Lite(tm) module is typical of those found in
Jenne-Aire and similar cook-tops. Input is 115 VAC, 4 mA, 50/60 Hz AC. C1
and D1 form a half wave doubler resulting in 60 Hz pulses with a peak of about
300 V and at point A and charges C2 to about 300 V through D2. R2, C3, and
DL1 form a relaxation oscillator triggering SCR1 to dump the charge built up
on C2 into T1 with a repetition rate of about 2 Hz.
C1 A D1 T1 o
H o----||----------------+-------|>|-------+-------+ +-----o HVP+
.1 uF D2 1N4007 | 1N4007 | | o ::(
250 V +----|>|----+ | +--+ ::(
| | | )::(
+---/\/\----+ | #20 )::( 1:35
| R1 1M | C2 _|_ )::(
| R2 / 1 uF --- +--+ ::(
| 18M \ DL1 400 V | __|__ ::(
| / NE-2 | _\_/_ +-----o HVP-
| | +--+ | / |
| +----|oo|----+---------' | SCR1
| C3 | +--+ | | | S316A
| .047 uF _|_ R3 / | | 400 V
| 250 V --- 180 \ | | 1 A
| | / | |
R4 2.7K | | | | |
N o---/\/\---+-----------+------------+----+-------+
Bug Zapper 1
You know the type - a purplish light with an occasional (or constant) Zap!
Zap! Zap! If you listen real closely, you may be able to hear the screams of
the unfortunate insects as well :-).
S1 R1 C1 C2 C1-C4: .5 uF, 400 V
H o----o/ o--+--/\/\--------||---+--------||---------+ D1-D5: 1N4007
| 25K D1 | D2 D3 | D4
| +---|>|---+---|>|---+---|>|---+---|>|---+
+-+ | C3 | C4 |
AC Line |o| FL1 +---+----||----+----+---+----)|----+----+--o +
+-+ Lamp | | R3 | | R4 | 500 to
| | +---/\/\---+ +---/\/\---+ 600 V
| R2 | 10M 10M to grid
N o----------+--/\/\---+------------------------------------------o -
25K
This is just a line powered voltage quadrupler. R1 and R2 provide current
limiting when the strike occurs (and should someone come in contact with the
grid). The lamp, FL1, includes the fluorescent bulb, ballast, and starter (if
required). Devices designed for jumbo size bugs (or small rodents) may use
slightly larger capacitors!
Bug Zapper 2
This is your basic brute force approach!
+---------------------+--o A
H o-------+ ||( |
)||( |
115VAC )||( Approx. 300V to |
)||( Fluorescent Tube |
N o-------+ ||( |
|| +-----o F1 F2 o-----+
||(
||(
||(
||(
||(
||(
||(
| +------------------------o B
G o---------+
F1 and F2 connect to the ends of the purple fluorescent tube.
A and B supply 5600VAC to the grid. We know this because it was one of the
features of the zapper - said it right on the box in a big yellow sunburst:
"5,600 Volts!!!". :)
Electronic Air Cleaner HV Generator
At least I assume this cute little circuit board is for an electronic air
cleaner or something similar (dust precipitator, positive/negative ion
generator, etc.)! I received the unit (no markings) by mistake in the mail.
However, I did check to make sure it wasn't a bomb before applying power. :-)
D1 T1 o
H o--------------|>|----+---+--------------------+ +-----o A
1N4007 | | Sidac __|__ SCR1 ::(
| | R3 D2 100 V _\_/_ T106B2 ::(
AC C1 | +--/\/\---|>| / | 200 V ::(
Line Power .15 uF _|_ 1.5K |<|--+--' | 4 A o ::( 350 ohms
IL1 LED 250V --- _|_ | +-------+ ::(
+--|<|---+ | C2 --- | | )::(
| R1 | R2 | .0047 uF | | | .1 ohm )::(
N o---+--/\/\--+--/\/\--+ +-----+--+ )::(
470 3.9K | +--+ +--+--o B
1 W 2 W | | R4 |
+--------------------------------+---/\/\---+
2.2M
The AC input is rectified by D1 and as it builds up past the threshold of the
sidac (D2, 100 V), SCR1 is triggered dumping a small energy storage capacitor
(C1) through the primary of the HV transformer, T1. This generates a HV pulse
in the secondary. In about .5 ms, the current drops low enough such that the
SCR turns off. As long as the instantaneous input voltage remains above about
100 V, this sequence of events repeats producing a burst of 5 or 6 discharges
per cycle of the 60 Hz AC input separated by approximately 13 ms of dead time.
A o
C3 |
+------||-------+
R5 R6 D3 | D4 D5 | D6 R7 R8
HV- o--/\/\---/\/\--+--|>|--+--|>|--+--|>|--+--|>|---/\/\--+--/\/\--o HV+
10M 10M | C4 | 220K | 10M
+------||-------+ |
D3-D6: 10 kV, 5 mA _|_ _|_
C3,C4: 200 pF, 10 kV --- C5 --- C6
C5,C6: 200 pF, 5 kV | |
B o--+----------------------+
The secondary side consists of a voltage tripler for the negative output
(HV-) and a simple rectifier for the positive output (HV+). This asymmetry is
due to the nature of the unidirectional drive to the transformer primary.
Auto Air Purifier HV Generator
Well, maybe :-). This thing is about the size of a hot-dog and plugs
into the cigarette lighter socket. It produces a bit of ozone and who knows
what else. Whether there is any effect on air quality (beneficial or
otherwise) or any other effects is questionable but it does contain a nice
little high voltage circuit.
DL1 +-+ |
o T1 +-------+-----|o|
+12 o---+--------+----------+---------------------+ ::( | +-+ |
| | | D 30T )::( | DL2 +-+
| | -_|_ 4.7uF #30 )::( +-----|o| |
| | --- 50V +------+ ::( 3000T | +-+
| _|_ C2 + | | ::( #44 | DL3 +-+ |
| --- 470pF +--------------|------+ ::( +-----|o|
| | | | F 30T )::( | +-+ |
+_|_ C1 | | D1 | #36 )::( | DL4 +-+
--- 33uF +----------|---+---|<|----|------+ ::( +-----|o| |
- | 16V | | | 1N4002 | o +--+ +-+
| / / | |/ C o | |
| R1 \ R2 \ +--------|Q1 TIP41 +--------------+
| 1K / 4.7K / |\ E | Grid
| \ \ | |
| | | | |
GND o---+--------+----------+--------------+--------------+
T1 is constructed on a 1/4" diameter ferrite core. The D (Drive) and F
(Feedback) windings are wound bifilar style (interleaved) directly on the
core. The O (Output) winding is wound on a nylon sleeve which slips over
the core and is split into 10 sections with an equal number of turns (100
each) with insulation in between them.
Ultrasonic Cleaner
Ultrasonic cleaning is a means of removing dirt and surface contamination from
intricate and/or delicate parts using powerful high frequency sound waves in
a liquid (water/detergent/solvent) bath.
R1 D1
H o------/\/\-------|>|----------+
1, 1/2 W EDA456 |
C1 D2 |
+----||----+----|>|-----+
| .1 uF | EDA456 | 2
| 200 V | +-----+---+ T1 +---+------->>------+
| R2 | _|_ C2 ):: o 4 | | |
+---/\/\---+ --- .8 uF D ):: +----+ | |
| 22K _|_ 200 V )::( + |
| 1 W - 1 o )::( ):: _|_
+-----------------+---------+ ::( O ):: L1 _x_ PT1
| R3 | 7 ::( ):: |
| +---/\/\---+ +-----+ ::( 5 + |
C \| | 10K, 1 W | F ):: +---+ | |
Q1 NPN |--+-+--------------+ 6 o ):: | | |
E /| | D3 R4 +---+ +----+------->>------+
| +--|<|---/\/\--+ _|_
| 47, 1 W | --- Input: 115 VAC, 50/60 Hz
| | | Output: 460 VAC, pulsed 80 kHz
N o------+-------------------+---+
Plasma Mug HV Generator
This circuit was found in a cheap "plasma mug" - a double wall partially
evacuated and gas-filled clear glass mug that glows in strange patterns when
sitting on the energizer base, depending on how it is touched or held. The
circuit is the typical one transistor oscillator driving a small potted
transformer. Q1 was on a heatsink. The hard potted HV transformer occupied a
volume of less than 1 inch cubed. Only the resistances of its windings have
been measured so far. Someday I may get around to determining more about it.
The listed power requirements for this unit were 12 V at 250 mA. It would run
on either 8 AA cells or a wall adapter. There was also a power switch as well
as the usual third contact on the power jack to disconnect the battery
when using the adapter (not shown).
D1 o T1 +------o HV Out
+12 o--|>|--+--------+-----+------------------------+ ::( (3" diam.
1N4004 | | | D .2 )::( copper disk)
| | / R1 ohms )::(
| | \ 10K +--------+ ::(
| | / | ::( 300
| | | R2 C4 | o ::( ohms
C1 +_|_ C2 _|_ +---/\/\---||---|--------+ ::(
470uF --- .1uF --- | 1K | F .2 )::(
25V - | | | 2SD882 |/ C ohms )::(
| | +-------------|Q1 +----+ ::(
| | _|_ C3 |\ E | +--+
| | --- 2nF | | o |
| | | | | |
GND o-------+--------+-----+---------------+---+------------+
Simple Linear Power Supplies
Simple Linear Power Supplies Introduction
This is a (currently somewhat meager) collection of basic power supply
circuits that will hopefully grow as time passes.
Converting an AC Output Wall Adapter to DC
Where a modest source of DC is required for an appliance or other device,
it may be possible to add a rectifier and filter capacitor (and possibly
a regulator as well) to a wall adapter with an AC output. While many wall
adapter output DC, some - modems and some phone answering machines, for
example - are just transformers and output low voltage AC.
Depending on your needs, you may find a suitable wall adapter in your junk
box (maybe from that 2400 baud modem that was all the rage a couple of years
ago!).
Bridge Rectifier Filter Capacitor
AC o-----+----|>|-------+---------+-----o DC (+)
~| |+ |
In from +----|<|----+ | +_|_ Out to powered device
AC wall | | C ___ or voltage regulator
Adapter +----|>|----|--+ - |
| | |
AC o-----+----|<|----+------------+-----o DC (-)
~ -
Considerations:
The following examples illustrate some of the possibilities.
Adding an IC regulator to either of these would permit an output of up to
a fraction to 2.5 V (depending on type) less than the filtered DC voltage.
Adding an IC Regulator to a Wall Adapter or Battery
For many applications, it is desirable to have a well regulated source of
DC power. This may be the case when running equipment from batteries as
well as from a wall adapter that outputs a DC voltage or the enhanced adapter
described in the section: Converting an AC output wall
adapter to DC.
I +-------+ O
Vin (+) o-----+---| LM317 |---+--------------+-----o Vout (+)
| +-------+ | |
| | A / |
| | \ R1 = 240 |
| | / | ___
_|_ C1 | | +_|_ C2 |_0_| LM317
--- .01 +-------+ --- 1 uF | | 1 - Adjust
| uF | - | |___| 2 - Output
| \ | ||| 3 - Input
| / R2 | 123
| \ |
| | |
Vin(-) o------+-------+----------------------+-----o Vout (-)
Note: Not all voltage regulator ICs use this pinout. If you are not using an
LM317, double check its pinout - as well as all the other specifications.
For a single output not referenced to a common, it doesn't matter
whether a positive voltage regulator (as shown) or negative voltage regulator
is used. However, were multiple power supplies like this are needed WITH a
common point, negative voltage regulator ICs must be used for the negative
ones.
78xx (Fixed Pos) 79xx (Fixed Neg) LM317 (Adj Pos) LM337 (Adj Neg)
___ ___ ___ ___
|_O_| |_O_| |_O_| |_O_|
| | 1 = Input | | 1 = Common | | 1 = Adjust | | 1 = Adjust
|___| 2 = Common |___| 2 = Input |___| 2 = Output |___| 2 = Input
||| 3 = Output ||| 3 = Output ||| 3 = Input ||| 3 = Output
123 123 123 123
Dual Output Power Supply Using Centertapped Transformer
Where a centertapped secondary is available, a power supply outputting both
positive and negative regulated or unregulated voltages can be constructed
basically like a pair of the circuits above. The following would work for
a +/- 15 VDC regulated unit to power analog circuitry like op-amps:
28VCT,1A
H o--+ T1
)|| D1 V+ In +------+ Out
)|| +--+--|>|-----+--------------+----| 7815 |---------+----o +15 VDC
)||( ~| D2 | C1 +_|_ +------+ C3 +_|_
)||( +--|<|--+ | 5,000uF --- Com | 10uF ---
)||( L1 | | 25V - | | 25V - |
110 VAC )|| +----------------------------+--------+------------+--+-o Analog
)||( L2 D3 | | C2 +_|_ | C4 +_|_ V Common
)||( +--|>|--|--+ 5,000uF --- Com | 10uF ---
)||( ~| D4 | 25V - | +------+ 25V - |
)|| +--+--|<|--+-----------------+----| 7915 |---------+---o -15 VDC
)|| V- In +------+ Out
N o--+ D1-D4: 1N4007 or 2 A bridge
Note: Pinouts for 78 and 79 series parts are NOT the same!
Dual Output Power Supply Using Non-Centertapped Transformer
Without a centertap, it is still possible to provide both polarities of output
voltage but a half wave configuration must be used. This is similar to the
wiring of a voltage doubler but we are using the common point as ground:
12V,1A
H o--+ T1
)|| D1 V+ In +------+ Out
)|| +--+--|>|------------+----| 7812 |---------+----o +12 VDC
)||( | C1 +_|_ +------+ C3 +_|_
110 VAC )||( | 10,000uF --- Com | 10uF ---
)||( | 25V - | | 25V - |
)|| +--|-----------------+--------+------------+--+-o Analog
)|| | C2 +_|_ | C4 +_|_ V Common
N o--+ | 10,000uF --- Com | 10uF ---
| D2 25V - | +------+ 25V - |
+--|<|------------+----| 7912 |---------+---o -12 VDC
V- In +------+ Out
For an unregulated supply, take the outputs from V+ and V-.
Higher Current Operation
By adding a PNP power transistor like a 2N2955 to either a fixed or adjustable
regulator, maximum current can be easily increased. The circuit below will
permit a very simple 3 to 5 A, 5 V power supply to be constructed assuming the
power transformer/rectifier can supply this current. Q1 MUST be mounted
on a large heat sink since it is dissipating power equal almost the entire
output current times the difference between input and output voltage! Also,
keep in mind that the filter capacitor(s) on the supply providing Vin must also
be sized accordingly to keep ripple to a manageable level.
E C
+-----. Q1 .-------------+
| _\___/_ |
| B| |
| R1 | I +------+ O |
Vin (+) o---+--/\/\--+-+---| 7805 |---+-+-----o Vout (+)
5 | +------+ | ___
| | C | |_O_| 7805
_|_ C1 | +_|_ C2 | | 1 - Input
--- .01 | --- 1 uF |___| 2 - Common
| uF | - | ||| 3 - Output
| | | 123
Vin(-) o---------------+-------+--------+-----o Vout (-)
The way this works is that once the current exceeds about Vbe(Q1)/5 A, Q1
turns on and bypasses current around the 7805.
Adjustable High Current Regulated Power Supply
This adds a gain stage to improve regulation compared to the circuit in the
section: Higher Current Operation and is shown using
an adjustable regulator though a fixed regulator could also be used. This
is similar to the circuit in the Texas Instruments LM317 datasheet. Although
not specified, I expect this is good for up to 5 A or more depending on the
actual voltage difference between input and output and the size of the heat
sink used for the power transistor, Q2. Using this configuration rather
than something like an emitter follower provides much better regulation
since the point of regulation for the LM317 is still the actual output of
the circuit.
+-------------------.C E.-------+
| Q2 _\___/_ |
| 2N3055 | |
| | R5 |
+---------.E C.------+---/\/\---+
| Q1 _\___/_ 500 |
| 2N2905 | |
| / R4 |
| \ 5K |
| / |
| R3 | I +-------+ O | 1N4002
Vin (+) o---+-+---/\/\---+---| LM317 |---+----+--+------+-------+---o Vout (+)
| 22 +-------+ | | | |
| | A / _|_ | |
| | \ R1 /_\ D1 | |
| | / 120 | | |
_|_ C1 | | | +_|_ C2 /
--- 10uF +-------+---+---+ --- 47uF \ RL*
| | | - | /
| \ R2 +_|_ C3 | |
| +->/ 5K --- 10uF | |
| | \ - | | |
| | | | | |
Vin(-) o------+---------------+--+-----------+----------+-------+---o Vout (-)
1.5 V Alkaline Cell Eliminator
I constructed this to provide a means of testing and experimenting with
electronic flash circuits and (modifications to these circuits) that run on
single Alkaline cells as their appetite for these is quite huge. See the
section: Up to 350 VDC Inverter from 1.5 V Alkaline Cell.
IC1
D1 I +--------+ O
+--|>|--+-----+--------+--| LT1084 |--+------+-----o +1.5 VDC
T1 | | | | +--------+ | |
H o--+ | D2 | | | | A / R1 | IC1
)|| +-+--|<|--|-+ | | | \ 220 | LT1084CP
)||( | | | | | / | ___
115 )||( 4 | | +_|_ C1 +_|_ C2 | | +_|_ C3 |_O_|
VAC )||( VAC | | --- 10K --- 10K +-------+ --- 470uF | | 1 - A
)||( D3 | | - | uF - | uF | - | 6.3V |___| 2 - O
)|| +-+--|>|--+ | | 10V | 10V \ R2 | ||| 3 - I
N o--+ | | | | / 62 | 123
| | | | \ | Front View
| D4 | | | | |
+--|<|----+---+--------+------+--------------+-----o Return
The power transformer (T1) that I used was actually rewound from one that
was rated at 12 V, 1 A. This was a high quality transformer, so removing
2/3rds of the secondary was quite a pain. Actually, the purpose was an
experiment to see if it could be done non-destructively. Conclusions: Just
barely. :-) Obviously, a transformer actually designed to produce about
4 or 5 V at 3 A could also be used.
Full Wave Voltage Doubler
A problem with most voltage doubler circuits is that the positive and negative
outputs operate on alternate half-cycles so ripple is at the power line
frequency rather than at twice the power line frequency. The transformer is
also not utilized efficiently since only half of the secondary winding is
passing current at any given time.
+-----------------+
||( | +
||( +---|>|---+-+---)|-----+---|>|---+
||( | D1 | C1 | D5 |
||( | | D3 | |
||( | +---|>|--+ | |
||( +----+ | | +---+
||( _|_ | +---|>|--|-+ | +_|_
||( //// | | D4 | | --- C3
||( | D2 | C2 | D6 | _|_
||( +---|>|-+---+---)|---+-----|>|---+ ////
||( | +
+---------------+
Boost Supply for PC
Boost Supply to Produce Clean Regulated +12 VDC shows
an approach for getting a higher voltage than +12 VDC from an unmodified PC
power supply. In this specific case, a source of +12 VDC for an audio or
instrumentation PCI card was needed to be derived from the normally noisy
+12 VDC output of a standard PC power supply. Any filtering would reduce
the voltage below an acceptable level. The 555 implements an oscillator
that runs at somewhere around 50 kHz which drives the MOSFET chopper
and stepdown transformer to generate a few VDC which is added to the original
12 VDC from the PC. This is then regulated down using the 7812. By only
generating a few V boost (just enough for the dropout requirements of the
linear regulator) rather than the full output voltage, the components can be
smaller since less power is involved.
Switching Power Supplies
Panasonic VCR Switching Power Supply (PV48XX and Clones)
This circuit was reverse engineered from the switching power supply from
a Panasonic VCR. It is typical of the small switchers used in the Panasonic
PV28XX, PV48XX, and many other models, their Magnavox clones, as well as other
Matsushita manufactured VCRs. Many VCRs of other brands use similar designs.
Power Supply for Small SVGA Color Monitor
This is the complete schematic for the switchmode power supply (SMPS)
from a small (probably 14 or 15 inch) "I guarantee you never heard of the
brand name" SVGA color monitor.
Inverter Circuits
Inverter Introduction
Most of these circuits were reversed engineered from commercial products. The
good news is that this means they probably all work somewhat reliably. The
bad news is that a custom wound transformer (you can build in most cases) will
be needed and there may be errors in the number of turns and wire sizes listed
since these were all determined without totally dismembering the unit in
question.
Super Simple Inverter
This circuit can be used to power a small strobe or fluorescent lamp. It will
generate over 400 VDC from a 12 VDC, 2.5 A power supply or an auto or marine
battery. While size, weight, and efficiency are nothing to write home about -
in fact, they are quite pitiful - all components are readily available (even
from Radio Shack) and construction is very straightforward. No custom coils
or transformers are required. If wired correctly, it will work.
C1 1 uF D2 1N4948 R2
+------||------+ T1 1.2kV PRV 1K 1W
| | +-----|>|-----/\/\---+------o +
| R1 4.7K, 1W | red ||( blk |
+-----/\/\-----+------+ ||( |
| yel )||( +_|_ C2
+ o----------------------------------+ ||( --- 300 uF
| red )||( - | 450 V
| +--------------+ ||( |
| Q1 | ||( blk |
6 to 12 | |/ C +--------------------+------o -
VDC, 2A +----| 2N3055 Stancor P-6134
D1 _|_ |\ E 117 V Primary (blk-blk)
1N4007 /_\ | 6.3 VCT Secondary (red-yel-red)
| |
- o------------+------+
Notes on Super Simple Inverter
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
AmerTac Fluorescent Lamp Inverter
(From: (Dennis Hawkins (n4mwd@amsat.org).)
Archer Mini Flashlight Fluorescent Lamp Inverter
The circuit below was reverse engineered from the Archer model number 61-3724
mini fluorescent/incandescent flashlight combo (no longer in the Radio Shack
catalog). The entire inverter fits in a space of 1-1/8" x 1" x 3/4". It is
powered by 3 C size Alkaline cells and drives a F4-T5 tube.
o T1
+ o----+----------+----------------+ o
| | ):: +--------------+-+
| \ D 28T )::( | |
| R1 / #26 )::( +|-|+
| 560 \ +---------+ ::( | - |
| / | ::( O 315T | | FL1
| | | o ::( #32 | | F4-T5
| +------|---------+ ::( | - |
| | | )::( +|-|+
+_|_ C1 | | F 28T )::( | |
--- 47 uF | | #32 ):: +--------------+-+
- | 16 V | | +---+
| | | Q1 | O = Output
| | C \| | D = Drive
| C2 _|_ |---+ F = Feedback
| .022 uF --- E /| |
| | | _|_ C3
| | | --- .022 uF
| | | |
o-----+----------+------+-----+
Notes on Archer mini flashlight fluorescent lamp inverter:
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Energizer Mini Flashlight Fluorescent Lamp
Inverter
The circuit below was reverse engineered from the Energizer model number
unknown (worn off) mini fluorescent/incandescent flashlight combo. The entire
inverter fits in a space of 1-1/8" x 1-1/8" x 3/4". It is powered by 4 AA
size Alkaline cells and drives a F4-T5 tube.
o T1 o
+ o----+----------+--------+-------------------+ +----------------+
| | C4 _|_ )::( H 16T #32 |
| \ 1000 --- D 32T ):: +--------------+ |
| R1 / pF | #26 )::( | |
| 360 \ +-------------------+ ::( +|-|+
| / | ::( | - |
| | | o ::( O 160T | | FL1
| +--------|-------------------+ ::( #32 | | F4-T5
| | | )::( | - |
+_|_ C1 | | F 16T )::( +|-|+
--- 47 uF | | #26 )::( | |
- | 16 V | | Q1 +---+ +--------------+-+
| | | MPX9610 |
| | C \| R2 | O = Output
| C2 _|_ |---+---/\/\--- D = Drive
| .047 uF --- E /| | 22 F = Feedback
| | | _|_ C3 H - Heater (filament)
| | | --- .01 uF
| | | |
o-----+----------+--------+-----+
Notes on Energizer Mini Flashlight Fluorescent Lamp Inverter
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Pocket Fluorescent Blacklight Inverter GH-RV-B1
(Schematic from: Axel Kanne (axel.k@swipnet.se).)
4.5 to 12V (4) T1(2)
+ o---+-------------------+---------------+ +-----+-+
| | R2 )::( | |
| +--/\/\--+ W1 )::( +|-|+
| 470 | )::( | - |
+_|_ C1 +-----|------+ ::( W3 | | FL1
--- 47uF |/ C _|_ C3 ::( | | (3)
| 16V +---+------| Q1 --- .015 ::( | - |
| | | (1)|\ E | uF ::( +|-|+
| C2 _|_ | | +------+ ::( | |
| .01uF --- | R1 | | W2 ):: +--+--+-+
| | +--/\/\--|-----|------+ |
| | 20 | | |
- o---+---------+------------+-----+--------------+
Notes on Pocket Fluorescent Blacklight Inverter GH-RV-B1
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Automotive Light Stick Inverter
(Circuit and description From: Manuel Kasper (mk@mediaklemm.com).)
o o
+12 V o----+--------+---------------------+ +------------+-+
| | )||( | |
| \ 28 turns )||( +|-|+
| 5.1K / #28 )||( | - |
| \ +----------------+ ||( | |
| / | ||( 280 turns | | F8T5
| | | o ||( #38 | |
| +----|----------------+ ||( | |
47 uF +_|_ | | )||( | - |
25V --- | | 28 turns )||( +|-|+
| | C \| Q1 #28 )||( | |
| | |------+---+---+ +---+--------+-+
| _|_ E /| | | |
| 10 nF --- | \ _|_ |
| | | 10K / --- 40 nF |
| | | \ | |
| | | | | |
o-----+--------+----+--------+---+------------+
Transistors with low gain don't seem to work well - BD237 and 2N5191 were reasonably good. It's easy to have it operate at more power - just decreasing the 5.1K resistor and adding a small heatsink works great.
The filter capacitor gets pretty warm; needs to be low ESR or it will probably overheat, especially at higher power levels.
In the original inverter, there was a connection between the secondary and ground. Strange - it doesn't seem to make any sense because nothing changes if you remove it. But they have got their reasons, I suppose.
This design can easily be modified for many other uses at lower or higher power. Note that its topology is similar to that of the circuit described in the section: Super Simple Inverter.
C2 .01 uF
+------||------+ T1 3
| | +------------+-+
| R1 1.5K | 4 o ::( | |
+-----/\/\-----+------+ ::( +|-|+
| 18T F )::( | - |
| 1 )::( | | FL1
+ o-----+----------|---------------------+ ::( O 350 T | | F8-T5
| | )::( | |
| | 25T D )::( | |
| R2 / 2 )::( | - |
| 68 \ +-------+------+ ::( +|-|+
6 to 12 _|_ C1 / Q1 | | ::( 5 | |
VDC --- 100 uF | | | +---+--------+-+
| 16 V | |/ C | |
| +----| 5609 +---------------+
| C3 _|_ |\ E NPN O = Output
| .027 uF --- | D = Drive
| | | F = Feedback
- o-------+----------+------+
The 350T O (Output) is wound first followed by the 25T D (Drive) and 18T F (Feedback) windings. There should be a strip of mylar insulating tape between each of the windings.
The number of turns were estimated without disassembly as follows:
Since it is very low power, no heat sink is used in this lamp. However, for other applications, one may be needed.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
The tube seems to like 75 VAC in order to 'fire it up'.
I used a 2N3053 transistor and a commonly available commercial 6 - 0 - 6 primary 240VAC 100mA secondary transformer. After 25 minutes constant usage, both transistor and transformer remained cool.
A variable PSU was connected, and the circuit worked first time. The required 75 VAC output was achieved with only 5 VDC input.
o T1
+ o----+---------+-------------------+
| | ):: o C2
| S1 | D 20T ):: +-------||------+-+
| Start |- #26 )::( .022 uF | |
| | )::( 600 V +|-|+
| | +-------+ ::( | - |
| R2 \ | ::( O 250T | |
| 270 / | o ::( #32 | | FL1
| \ +------|-------+ ::( | | T5 lamp
+_|_ C1 | | | F/S 7T )::( | |
--- 100 uF | | | #32 ):: +--------+ | - |
- | 16 V +----|------|---+---+ | +|-|+
| | | | | | |
| | | +-----------------|------+-+
| | +-----------+ |
| S2 | | | | O = Output
| _|_ Off | |/ C | | D = Drive
+-- --+--------+----| Q1 | | F/S = Feedback/starting
| | | |\ E 2SC1826 _|_ D2 |
| \ _|_ | /_\ 1N4007 |
| R1 / D1 /_\ | | |
| 220 \ 1N4148 | | | |
| | | | | |
o-----+-----+--------+------+-----------+---------+
The approximate measured operating parameters are shown in the chart below.
The two values of input current are for starting/running (starting is with
the Start button, S1, depressed.
Lamp type ---> F4-T5 F6-T5 F13-T5
V(in) I(in) I(in) I(in)
-------------------------------------------------------------
3 V .9/.6 A - -
4 V 1.1/.7 A 1.1/.8 A -
5 V 1.3/.8 A 1.2/.9 A -
6 V - 1.4/1.0 A 1.6/.95 A
7 V - - 1.7/1.0 A
8 V - - 1.8/1.2 A
9 V - - 2.1/1.3 A
10 V - - 2.2/1.4 A
The core is just a straight piece of ferrite 1/4" x 1/4" x 1-3/8" It is fully open - there is no gap.
Use a good heat sink for continuous operation at higher power levels (6 V input or above). The type used (2SC1826) was a replacement after I fried the unidentified transistor originally installed (103-SV2P001).
Like a regular manual start preheat fluorescent fixture, the start switch, must be depressed until the lamp comes on at full brightness indicating that the filaments are adequately heated.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
I have used it with fluorescent tubes of many sizes: F6-T5, F13-T5, F15-T12, and F20-T12. The arc will be sustained with the filaments hot on an input as low as about 3.5 to 4 V (with a new tube) but during starting, an input voltage of about 5 or 6 V may be needed until the filaments are hot enough to sustain the arc at the lower voltage.
Two nearly identical circuits are shown.
+Vcc o T1
o Q1 +----------------+
| | )::
+ B |/ C )::
L1 ::( +------| MJE3055T ):: C1
24T ::( | |\ E D 15T ):: +----------||---------+-+
#22 ::( | | #26 )::( .0039 uF | |
+ | -_- )::( 600 V +|-|+
| | )::( | - |
+--|-------------------------+ ::( | |
| | )::( | |
| | Q2 _-_ )::( | |
| | | )::( O 600T | | FL1
| | B |/ E D 15T )::( #32 | |
| | ----| MJE3055T #26 )::( | |
| | | |\ C )::( | |
| | | | )::( | |
| | | +----------------+ ::( | - |
| | | ::( +|-|+
| | | o ::( | |
| | -----------------------+ :: +---------------------+-+
| | F 10T )::
| | #32 )::
| | +---------+ :: O = Output
| | | F 10T ):: D = Drive
| | | #32 ):: F = Feedback
| +-------------------------+
| |
| R1 | R2
+----------/\/\/\--+--/\/\/\--+
220 22 _|_
1 W 2 W -
+Vcc o T1
o Q1 +----------------+
| | )::
+ B |/ C ):: C1
L1 ::( +---+----| MJE3055T ):: +----------||---------+-+
24T ::( | __|__ |\ E D 15T )::( .0039 uF | |
#22 ::( | _/_\_ _|_ #26 )::( 600 V +|-|+
+ | _|_ - )::( | - |
| | - D1 1N4148 )::( | |
+--|---------------------------+ ::( | |
| | _-_ D2 1N4148 )::( | |
| | __|__ _-_ )::( O 600T | | FL1
| | _\_/_ | )::( #32 | |
| | | B |/ E D 15T )::( | |
| | +----| MJE3055T #26 )::( | |
| | | |\ C )::( | |
/ | | | )::( | - |
R1 \ | | Q2 +----------------+ ::( +|-|+
1K / | | ::( | |
\ | | o :: +---------------------+-+
| | +-----------------------+ ::
| | F 10T ):: O = Output
| | R2 22, 2 W #32 ):: D = Drive
+--+---------/\/\/\------------+ F = Feedback
The measured input current at various input voltages for two lamp types are shown in the chart below. SV (Starting Voltage) is the minimum input voltage required to preheat the filaments before the lamp will turn on (current is lower until filaments are hot). FB (Full Brightness) is the point at which the lamp appears to be operating at the same intensity as if it were installed in a normal 115 VAC fixture.
Lamp type ---> F13-T5 F20-T12
V(in) I(in) I(in)
---------------------------------------------------
3 V - 1.37 A
4 V 1.76 A 1.52 A (SV)
5 V 1.80 A (SV) 1.60 A
6 V 1.90 A 1.65 A
7 V 1.96 A (FB) 1.70 A
8 V 2.02 A 1.80 A
9 V 2.16 A 1.90 A
10 V 2.33 A 2.05 A
11 V - 2.30 A (FB)
12 V - 2.60 A
Each E core is 1" x 1/2" x 1/4" overall. The outer legs of the core are 1/8" thick. The central leg is 1/4" square. The square nylon bobbin has a diameter of 5/16" and length of 3/8".
The 600T O (Output) is wound first followed by the 15T D (Drive) and 10T F (Feedback) windings. For convenience, wind the D and F windings bifiler style (the two wires together). Determine the appropriate connections with an ohmmeter (or label the ends). The centertaps are brought out to terminals. Try to distribute the O winding uniformly across the entire bobbin area by winding it in multiple layers. This will assure that no wires with a significant voltage difference are adjacent. There should be a strip of insulating tape between the O and the other windings.
For operation above about 6 V, a pair of good heat sinks will be required. However, power dissipation in the transistors does not seem to increase as much as expected - the base drive is probably more optimal at higher input voltage.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
I planned one week of camping with my friends this summer, so I wanted to make one fluorescent tube run on 12V and studied a lot of Internet places for the ideas. I made some of the circuits (some of them I found on your site) but the performance was not as I expected. Yes, they do run a 8W tube but the brightness is quite obviously lower than when the tube is run on mains supply. Then I started to study app-notes of many different electronic ballasts for fluoro-tubes and got the idea what was wrong. I send my conclusions to you with the hope that it could help others in selecting the good circuit with less trouble than I got :))
So, it seams that far better topology for fluorescent tube inverters is symmetrical push-pull inverter, such the one described in "Medium Power Fluorescent Lamp Inverter". There is only slightly higher cost for this (one power transistor more), but also fewer resistors and capacitors!
The output voltage of this circuit is alternating (+/-) square wave. The tube gets constant power supply (it lights during positive as well as during negative half-cycle, which means AC), and it doesn't turn off at all.
One additional good feature of this capacitor is that it heats the filaments of the electrodes even during normal operation of the tube but in much lower rate (about 5% of the preheating current). It may look as a fault but it doesn't. The lamp life would be longer if the filaments are hotter.
Re = 1.2V/I(Amps)
With a 12 VDC power supply, this resistor produces around 10% of power loss but if the compactness of the device is important, it is acceptable. Without it the transistors would dissipate almost the same amount of heat as resistor dissipates when is present, so I suggest using it anyway. The inverter runs much more stablely with it and the transistors are much less stressed, which ensures long and reliable operation of the inverter.
+Vcc o T1
o Q1 +--+-------------+
| | | )::
| B |/ C | )::
| +---------| | ):: C1
| | |\ E | D1 22T ):: +-----||-------+
| | | | #26 )::(o 4.7 nF |
| | +--|-----+ )::( 1200V |
| | 4k7 | | )::( |
| +----+-/\/\/-+-|--+ | )::( |
| | | | | | | )::( | +---------+
| | +--||---+ | | | )::( | | |
| | 1nF | | | )::( +|-|+ |
| | | | | )::( | - | |
+--|--------------|-------------+ ::( | | |
| | 4k7 | | | o)::( | | |
| | +----/\/\/--+ | | )::( | | |
| | | | | | )::( | | |
| | +-----||----+ | | )::( O 500T | | 2n2 _|_
| | | 1nF | | D2 22T )::( #32 | | 1200V ___
| | | | | #26 )::( | | |
| | | Q2 +-----+ | )::( | | |
| | | | | | )::( | | |
| | | B |/ C | | )::( | | |
| | +------| | | )::( | | |
| | | |\ E | | )::( Fluoro-tube | | |
| | | | | | )::( 18W | | |
| | | | +--|-------+ ::( | - | |
| | | | | ::( +|-|+ |
| | | 1k | | ::( | | |
| | +-/\/\/--+ | +--------------+ +---------+
| | | |
| +----/\/\/--+ |
+_|_ 1k | | Re Q1,Q2: BD243C
--- +--------+--/\/\/\---+
- | 100uF/16V 1 Ohm |
| 2W |
+-----------------------------------+
_|_
_
All resistors are rated to 1/4 W except Re, which is 2 to 4 W.
My lamp has survived abt 20 hours being run on this circuit. I will send you an update if I notice something else useful or interesting.
The same basic circuit could be used on 220 to 240 VAC, 50 Hz but the voltage ratings of the filter capacitor and possibly the transistors would need to increase, and probably some other changes would be needed. This in fact is what 230 VAC CFL ballasts do. See Pavouk.org - Compact Fluorescent Lamps. There are schematics for at least 11 different model CFLs!
However, note that these ballasts do not seem to be very tolerant of any sort of fault in the lamp circuit itself and may fail instantly if there is a short, open, intermittent connection, or wrong type or size lamp. Thus care should be taken if attempting to use the ballast to power anything other than the original lamp. Double check that all wiring is correct and secure before applying power.
This inverter uses a pair of N and P channel 250 V, 2 to 2.5 A, MOSFETs in a self oscillating configuration with a transformer (actually labeled L3 on the schematic) boosting the half-bridge output voltage. (L3 may actually have at least one of its windings wired with Litz multistrand insulated wire based on the appearance of the wire ends at its terminals.) Gate drive feedback is via a series L-C circuit. A Positive Temperature Coefficient thermistor provides current to power the tube filaments and then increases to a high resistance while the lamp is running. This is easier on the filaments during starting but uses a bit extra power than might be possible with some sort of active switching circuit to disable them. Protection is provided by a real 1.5 A mini glass fuse wired directly to the center of the CFL screw base.
The same basic circuit could be used on 220 to 240 VAC, 50 Hz but the voltage ratings of the filter capacitor and MOSFETs would need to increase, the L3 turns-ratio would decrease, and probably some other changes would be needed.
However, note that these ballasts do not seem to be very tolerant of any sort of fault in the lamp circuit itself and may fail instantly if there is a short, open, intermittent connection, or wrong type or size lamp. Thus care should be taken if attempting to use the ballast to power anything other than the original lamp. Double check that all wiring is correct and secure before applying power.
Modifications for higher or lower output voltage are easily achieved. For example, a fast cycle strobe requiring 330 VDC, would only require using three times the number of turns on the Output winding and the addition of a bridge rectifier to charge the energy storage capacitor(s). Alternatively, the inverter could be used as-is with the addition of a voltage tripler. A tripler rather than doubler is needed because of the squarewave output. (The RMS and peak voltages are the same so you don't get the boost of 1.414 as you do with the sinusoidal waveform from the power company.)
Circuits similar to this will also be found inside UPSs (Uninterruptible Power Sources) so if all you want is a cheap low voltage DC to line voltage inverter, find a dead UPS - there's a good chance the battery is bad, not the electronics! (However, it may not be designed for 12 VDC input.)
3 o
+12 VDC +--------+--------------+
o | | )||
| |/ C +_|_ C1 )||
S F1 20 A +------| Q1 --- 10 uF 31T D )|| o 2
| | |\ E -_|_ 160 V #13 )|| +---------o AC Hot
\ S1 | _|_ - )||(
| Pwr | - )||(
| | 4 )||(
+------+---|--------------------------------+ ||(
| | | _-_ )||(
| | | | )||( O 360T