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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.
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---/\/\---+-----------+------------+----+-------+
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:
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!
(From: Andrew Bowers (falcon_@geocities.com).)
This is from my friend's bug zapper:
+---------------------+--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!!!". :)
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.)
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.
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).
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.
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 +-+ |
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.
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.
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------+-------------------+---+
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:
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:
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:
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.
Here are pinouts for the most common types:
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
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.
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!
For an unregulated supply, take the outputs from V+ and V-.
Here is a circuit for a +/- 12 VDC supply:
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-.
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.
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.
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.
+-------------------.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 (-)
* 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., .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.
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.
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 at: George Hrischenko's Genuine Full Wave Voltage Doubler Page.
+-----------------+
||( | +
||( +---|>|---+-+---)|-----+---|>|---+
||( | D1 | C1 | D5 |
||( | | D3 | |
||( | +---|>|--+ | |
||( +----+ | | +---+
||( _|_ | +---|>|--|-+ | +_|_
||( //// | | D4 | | --- C3
||( | D2 | C2 | D6 | _|_
||( +---|>|-+---+---)|---+-----|>|---+ ////
||( | +
+---------------+
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
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 5.1 k 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.
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
| | | |/ E _-_ C2 31T D )||( #20
| / | ----| Q2 -_|_ 10 uF #13 )||(
C3 +_|_ R3 \ | | |\ C --- 160 V )||(
10 uF --- 150 / | | | + | 5 )||(
50 V - | 5 W \ | | +--------+--------------+ ||(
| | | | ||( 1
| | | +---------------------+ || +------o AC Neutral
| | | | 6 o ||
+------+---|-------------------+ +-------+ || T1
| | F 17T )||
| R3 2.7 10 W | #24 7 )|| O = Output
| +----/\/\----+------------+ || D = Drive
| |R2 2.7 10 W 10 o || F = Feedback
| +----/\/\-----------------+ ||
| _|_ F 17T )|| (Pin numbers from
| - #24 8 )|| Triplite unit.)
+--------------------------------+
The core dimensions are 3-3/4" x 3-1/8" x 1-1/8" overall. The outer legs of the core are 5/8" thick. The central leg is 1" wide. The square bobbin has a diameter of 1-3/8".
The 360T O (Output) secondary is wound first as 4 or 5 insulated layers followed by the 31T D (Drive) and 17T F (Feedback) windings. There are insulating layers between each of the windings.
The number of turns were estimated without disassembly as follows: