Voltage Inverter II

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This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will operate at an input voltage from around 5V to 20V and produce a output from +-2.5V to +-10V.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	1M Linear Pot
C1,C2	2	15uf 25V Electrolytic Capacitor
U1	1	LM380 Audio Amp Chip
MISC	1	Heatsink For U1, Binding Posts (For Input/Output), Wire, Board

Notes

U1 dissipates around 1W and will therefore require a heatsink.

R1 is used to equalize the outputs. The first time you use the circuit, it should be set to mid range and then adjusted with the aid of a voltmeter. Measure each output while adjusting. The circuit is calibrated when both outputs read the same voltage (either positive or negative).

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Comments

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BillP Voltage Inverter II Saturday, October 10, 2009 2:24:12 AM

The original circuit appeared in the National Semiconductor Data Books as AN-69 (application note) in Dec. 1972. The circuit is correct as shown, however, the outputs as shown here are slightly different than in AN-69. AN-69 shows the 'positive' from the center (0) to the upper output as V+ with an arrow pointing upwards (from 0) to the upper output. It then shows the 'negative' from the lower output to center (0) as V- with an arrow pointing upwards (from lower) to the center (0).

innominata Voltage Inverter II Thursday, July 16, 2009 2:20:03 AM

to the previous poster : Imagine a 9v battery. It is connected to the ground of the 9v source. The outputs from this circuit are 4.5v, 0, -4.5v. The potential difference between 4.5 and -4.5 is 9, exactly the same as the battery. As long as you dont earth anything else to the 9v battery's -ve terminal believing its 0v, you will be fine (its actually -4.5v with reference to the 4.5v and 0v outputs). Voltage can be a tricky thing to get your head around. There is no such thing in a circuit run off a battery as 'earth'. Just a difference in voltage potential between the two terminals.

anonymous Voltage Inverter II Wednesday, June 03, 2009 8:02:31 AM

Have you ever considered the fact that it is physically impossible for it to work? Look at the -V/2 output, it's connected to the ground

abel gardener 10kva inverter circuit Sunday, March 08, 2009 5:49:09 PM

you have been a great help to many peoples in career and more especially to me thanks for your good works

victor POWER INVERTER BOARD Wednesday, January 14, 2009 8:11:12 AM

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. 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. 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------------+------+

Michael Oladipo 12V to 120V inverter Monday, November 24, 2008 7:58:03 AM

the astable multivibrator is not working. It will be wise and more appropriate to use a driver/pre amplifier to drive the power transistor before feeding it to the transformer.

Ohztech Voltage Inverter II Thursday, April 10, 2008 1:06:51 AM

Hi! i find this design very usefull, thanks... i would like to know if there will be a change to increase the ouput voltage to at least ą12 to ą15 volts? What will be the new design?

Ralph Saliba Microwave Oven Secondary Voltage Doubler Sunday, February 10, 2008 3:41:43 AM

Can you be kind enough to furnish me with a circuit to double the Secondary output voltage of this transformer. I believe that the current in this respect is divided by 2. Regards Ralph

Haz Voltage Inverter II Saturday, December 15, 2007 8:22:35 AM

Hey! You couldn't possibly be able to tell me how many amps this can handle? I need it so i can create a phase shift oscillator for my op amp, that means i can make a near sine wave to power my inverter!

Paul Voltage Inverter II Wednesday, December 12, 2007 5:48:38 PM

Your site is fantastic I have viewed Your site please can you give me more explanation on the complete circuit of 5KVA inverter and 10KVA Inverter and there circuit board with the automatic changer thanks you

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BillP	Voltage Inverter II	Saturday, October 10, 2009 2:24:12 AM
The original circuit appeared in the National Semiconductor Data Books as AN-69 (application note) in Dec. 1972. The circuit is correct as shown, however, the outputs as shown here are slightly different than in AN-69. AN-69 shows the 'positive' from the center (0) to the upper output as V+ with an arrow pointing upwards (from 0) to the upper output. It then shows the 'negative' from the lower output to center (0) as V- with an arrow pointing upwards (from lower) to the center (0).
innominata	Voltage Inverter II	Thursday, July 16, 2009 2:20:03 AM
to the previous poster : Imagine a 9v battery. It is connected to the ground of the 9v source. The outputs from this circuit are 4.5v, 0, -4.5v. The potential difference between 4.5 and -4.5 is 9, exactly the same as the battery. As long as you dont earth anything else to the 9v battery's -ve terminal believing its 0v, you will be fine (its actually -4.5v with reference to the 4.5v and 0v outputs). Voltage can be a tricky thing to get your head around. There is no such thing in a circuit run off a battery as 'earth'. Just a difference in voltage potential between the two terminals.
anonymous	Voltage Inverter II	Wednesday, June 03, 2009 8:02:31 AM
Have you ever considered the fact that it is physically impossible for it to work? Look at the -V/2 output, it's connected to the ground
abel gardener	10kva inverter circuit	Sunday, March 08, 2009 5:49:09 PM
you have been a great help to many peoples in career and more especially to me thanks for your good works
victor	POWER INVERTER BOARD	Wednesday, January 14, 2009 8:11:12 AM
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. 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. 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------------+------+
Michael Oladipo	12V to 120V inverter	Monday, November 24, 2008 7:58:03 AM
the astable multivibrator is not working. It will be wise and more appropriate to use a driver/pre amplifier to drive the power transistor before feeding it to the transformer.
Ohztech	Voltage Inverter II	Thursday, April 10, 2008 1:06:51 AM
Hi! i find this design very usefull, thanks... i would like to know if there will be a change to increase the ouput voltage to at least ą12 to ą15 volts? What will be the new design?
Ralph Saliba	Microwave Oven Secondary Voltage Doubler	Sunday, February 10, 2008 3:41:43 AM
Can you be kind enough to furnish me with a circuit to double the Secondary output voltage of this transformer. I believe that the current in this respect is divided by 2. Regards Ralph
Haz	Voltage Inverter II	Saturday, December 15, 2007 8:22:35 AM
Hey! You couldn't possibly be able to tell me how many amps this can handle? I need it so i can create a phase shift oscillator for my op amp, that means i can make a near sine wave to power my inverter!
Paul	Voltage Inverter II	Wednesday, December 12, 2007 5:48:38 PM
Your site is fantastic I have viewed Your site please can you give me more explanation on the complete circuit of 5KVA inverter and 10KVA Inverter and there circuit board with the automatic changer thanks you