This is a cheap-and-dirty experimenter's circuit. I tested this and it worked for me, but I disclaim all warranties!
+------+
+--------+ |( |
| )|( |
| T1 )|(-- |
| )|( |
- | + |( |
Cout === | + | C C C C
+ | Gnd | +--||---+---||--+---||--+---||--+
+------+ Gnd | | | | |
| | +->|+->|+->|+->|+->|+->|+->|+->|+->|+--+
| +---------+ | | | | | |
----------------- | | +---||--+---||--+---||--+---||--+ |
| 8 7 6 5 | === C1 > | C C C C |
| | | > | |
) LM386 | | R4 > === 2C |
| | > > | HV Out
| 1 2 3 4 | > R1 | Gnd
----------------- > |
| > |
> | C3 ===
R3 > | |
> | Gnd
> |
+-----+----------+
| |
| >
C2 === > R2
| >
| >
+-----+
|
Gnd
Connections to the LM386 Amplifier IC Not Shown:
Pins 2 and 4 Go to Gnd.
Pin 6 gets B+ and also a capacitor (not shown) to Pin 4.
This capacitor should be a .1 uF ceramic cap in parallel with an electrolytic
cap of at least 10 uF. This circuit sometimes works better with these, but
usually works without.
Components Shown Above:
The LM386 is an audio amplifier IC, Radio Shack Catalog # 276-1731.
T1 is a Radio Shack audio transformer, 273-1380. The red and white leads get the audio output from the LM386. (One grounded, one fed from Cout.) The blue and green leads feed the voltage multiplier. (One grounded, one feeds the first diode.)
Cout is at least 100 uF. The positive terminal goes to Pin 5 of the LM386, the negative terminal goes to the transformer.
The eight capacitors labeled C should be .1 to 1 uF rated at least 50 volts,
preferably at least 100 volts. They will typically get 70 volts.
The capacitor labeled 2C should be .2 to 2.2 uF rated at least 35 volts.
For best results, C should be at least .2uf, preferably at least .47 uF. 2C
should be at least .47 uF, preferably at least 1 uF.
The nine diodes are 1N914/1N4148. (R.S. Cat. # 276-1620 for 50 diodes or 276-276-1122 for ten diodes)
The two capacitors C1 and C2 should be .01 uF, preferably not a Z5U ceramic. R.S. Cat. # 272-1065 works well.
The resistors R1 and R2 are 4.7K.
R3 is a 10K resistor that I recommend, even though none at all usually works.
R4 is a 10 ohm resistor and C3 is a .1 uF capacitor. These are recommended in documentation for the LM386 in order to avoid ultrasonic oscillation. However, the LM386 usually does not oscillate if these are omitted.
The transformer steps the output AC of the 386 by a factor of about 10.
The nine diodes and nine capacitors form a voltage multiplying rectifier circuit. The DC output voltage is (not quite due to diode losses) nine times the peak voltage of the AC delivered by the transformer.
At voltages near and above 9 volts, the rated limits of some of the components in this circuit are pushed. However, this circuit seems to work at up to 12 volts without anything burning out, or at least not too quickly. However, the LM386 seems to get rather hot at 12 volts. This circuit should be used as a cheap-and-dirty experimenter's circuit rather than a highly reliable circuit unless the supply voltage is near or under 7 volts. It is not a really ideal "inverter" circuit but a cheap-dirty one that can be made from Radio Shack parts.
The ultimate output voltage with a supply voltage of 9 volts is about 300 volts. If you want something different, you can use a different number of diodes and capacitors.
CAUTION - This circuit produces high voltage. Even if you get shocked by a part of the circuit that may not kill you, the shock might cause you bump into something else that might.
This is a cheap-and-dirty experimenter's circuit. I tested this and it worked for me, but I disclaim all warranties!
| |
NOTE: --+-- is connected, --|-- is not connected.
| |
NOTE: Some IC connections not shown, see below.
+--------+ +--------+ +--------+
| _____|___ _______________ | _____|___ | _____|___
| | 8 7 6 5 | | | | | 8 7 6 5 | | | 8 7 6 5 |
| | | | | | | | | | |
| | 555 | | 4013 | | | 555 | | | 555 |
| | | | | | | | | | |
| | 1 2 3 4 | | 1 2 3 4 5 6 7 | | | 1 2 3 4 | | | 1 2 3 4 |
| |_________| |_______________| | |_________| | |_________|
| | | | | | | | | | | | |
+------+ | | +-|---+ +------+ | +------+ |
| | | | | | | | |
+--VVVV--+--------|-|-+ | | | |
| 6.8K | +--------------+ | | |
| +-------------------------|------+ |
===.1uF | |
| > >
gnd >R1 R2>
> >
| |
|B |B
----- gnd -----
TIP3055 C/ \E | E/ \C TIP3055
/ \____+____/ \
D1 T1 | | |
+ <-----+----------|<|----+--- ----+---|<|----+----|>|---|
| | )||( Z1 Z2 |
| | )||( |
| +---+-|>|----+ )||( |
400 VDC ===C1 | | D2 )||+----> +12VDC |
| | | )||( |
| | ===C2 )||( |
| | | )||( |
- <-----+----+ +------------ --------------------------+
IC connections not shown:
Pin 1 of all 555's goes to ground.
Pins 4 and 8 of all 555's go to +12 volts DC. It is recommended to have a
power supply bypass capacitor of at least .1 uF from Pin 8 to ground on
each 555.
Pin 5 of all 555's goes to ground through a capacitor of .01 to .1 uF.
Pin 7 of all 555's is left unconnected.
Pin 14 of the 4013 gets connected to +12 volts DC.
Pins 4, 6, 7, 8, 9, 10, and 11 of the 4013 get connected to ground.
Pins 12 and 13 of the 4013 are left unconnected.
Notes:
R1 and R2 are each parallel pairs of 150 ohm, 1/2 watt. (Otherwise, use
75 ohm 1 watt, not available at Radio Shack.)
D1 and D2 are any type rectifier diode rated at least 1 amp and 600 volts.
C1 and C2 are 1 uF 250 VDC, such as Radio Shack 272-1055. Should you get
the 200 volt version, the inverter will still work but reliability will be
slightly compromised, since the voltage on these capacitors will likely
slightly exceed 200 volts.
T1 is a 12 volt center-tap, 3 amp transformer, such as Radio Shack 273-1511.
This transformer is used as a step-up transformer and will put out approx.
200 volts square wave AC.
It is recommended to parallel the transistors with zener diode pairs. Put
three 12 volt 1 watt zener diodes in series, all three in the same direction.
Put one of these triplets from collector to base of each TIP3055 transistor,
with the cathode end towards the collector. These zener diode banks are
shown as Z1 and Z2.
The transistors must be appropriately heat-sinked. The Radio Shack 276-1363
heat sink is adequate for one transistor if heatsink grease is used and the
heatsinks are not enclosed in a small, poorly ventillated space. It is not
necessary to use any heatsink insulators if the heatsinks will not be
connected nor shorting to anything.
DANGER: This circuit has high voltage capable of causing fatal electric shock.
Do anything described here only at your own risk.
This inverter will charge up capacitors to approx. 400 volts or slightly more.
Therefore, it is recommended to use energy storage capacitors rated at least
for 400 and preferably for 450 volts.For some ideas for flashtubes and capacitors suitable for larger strobes and rated for these voltages, go to my Large Xenon Strobe Parts Page.
You can use the usual 330 or 350 volt capacitors if you can ensure that flashing will occur and reliably discharge the capacitor before the voltage builds up to an excessive level, or if you add circuitry to disable this circuit should flashing fail to keep the energy storage capacitor's voltage from building up past its rating.
Alternatively, you can use an 18 volt centertap transformer, to get a maximum output voltage slightly under 300 volts. You will have to double C1 and C2 to get similar power output.
Another alternative is to use a lower power transformer and reduce C1 and C2 for a lower power output.
With an energy storage capacitor capable of withstanding 450 volts and stored energy not exceeding 6 joules (60 uF at 450V or 76 uf at 400V), the Radio Shack flashtube will operate safely if it is flashed infrequently enough to not get an average power input of more than 6 watts. (1 flash per second with the 6 joule limit.)
Written by Don Klipstein.
Please read my Copyright and authorship info.
Please read my Disclaimer.
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