Voltage Inverter

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This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn't add much in the way of size and cost to a project.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	24K 1/4 Watt Resistor
R2	1	56K 1/4 Watt Resistor
C1	1	3300pF 25V Ceramic Capacitor
C2	1	47uF 25V Electrolytic Capacitor
C3	1	10uF 25V Electrolytic Capacitor
C4	1	100uF 25V Electrolytic Capacitor
D1, D2	2	1N4148 Silicon Diode
U1	1	555 Timer
MISC	1	Wire, Board

Notes

V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps.

For better regulation, a 79LOxx series regulator can be used.

A zener diode may also be used to regualte the output voltage.

Thanks to audioguru for correcting some errors in the original schematic. Read about it in this forum topic.

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Comments

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Colin Mitchell Voltage Inverter Saturday, September 11, 2010 9:16:51 PM

The output current of this circuit is limited to less than 90mA as this is the maximum current capability of a 1N4148 signal diode.

luke Voltage Inverter Thursday, June 03, 2010 9:43:05 AM

I have just made this circuit 12V in i was only seeing a max of -6V out. output oscillating from -3v to -6v, never stable. The circuit was powered for no more than five minutes and exsessive heat was drawn,left any longer i think the 555 would blown. i would not recomend this circuit, but by all means test it yourself.

Ali Bali 555 Voltage Inverter Sunday, February 21, 2010 7:08:30 AM

The circuit operates as a free running AC Square Wave oscillator. Power is connected across pin's 4 +ve & 1 -ve. The output is then rectified i.e. converted to DC via D1 & D2 then smoothed via C3. For power line noise rejection, add a filter cap across the supply say 1000uf and a 0.1uf. This is a good common circuit for producing a -ve ref voltage from a +ve supply.

tamilselvi Voltage Inverter Tuesday, January 19, 2010 10:11:48 AM

Eh guys can i know the o/p waveform of this circuit....

Solo Voltage Inverter Sunday, September 20, 2009 12:42:10 PM

Hey, I made this circuit because i need dual power supply for my op amp project. It works BUT the power supply line (+12 V line) now has noise inteference. can anyone give a hint why it happens?

jazzfreak Voltage Inverter Monday, June 01, 2009 6:31:07 PM

Some of you who think that this is an inverter that steps up voltage (12v to 120v) should think twice. This is a VOLTAGE or "POLARITY" inverter, which means this circuit switches polarity!

Sean Voltage Inverter Thursday, March 26, 2009 12:37:20 AM

Ummmm, power input to the circuit is "V+". Vahid, 13V at 8 amps?!?!?! Damn. If you need about 1 amp, use an LM317. Excellant job on the documentation of the inverter, simple and to the point. Thank you!!!!!!

vahid Voltage Inverter Sunday, February 15, 2009 6:53:45 AM

Hi can you help me please. i have 30volt DC and i vant to convert it to 13.5 (8A). i need any circuit design that is helpful.

manny Voltage Inverter Thursday, September 18, 2008 3:14:56 AM

where is the connection to power the circuit, sorry can't find it how will it operate without a supply? thanx

Liston of University of Cebu Computer Engineering Dept.(Philippines) Voltage Inverter(explain) Monday, August 04, 2008 4:41:28 AM

IC 555 there is only used for oscillation, to have an AC current and the output is connected to transformer to have a higher voltage.

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Colin Mitchell	Voltage Inverter	Saturday, September 11, 2010 9:16:51 PM
The output current of this circuit is limited to less than 90mA as this is the maximum current capability of a 1N4148 signal diode.
luke	Voltage Inverter	Thursday, June 03, 2010 9:43:05 AM
I have just made this circuit 12V in i was only seeing a max of -6V out. output oscillating from -3v to -6v, never stable. The circuit was powered for no more than five minutes and exsessive heat was drawn,left any longer i think the 555 would blown. i would not recomend this circuit, but by all means test it yourself.
Ali Bali	555 Voltage Inverter	Sunday, February 21, 2010 7:08:30 AM
The circuit operates as a free running AC Square Wave oscillator. Power is connected across pin's 4 +ve & 1 -ve. The output is then rectified i.e. converted to DC via D1 & D2 then smoothed via C3. For power line noise rejection, add a filter cap across the supply say 1000uf and a 0.1uf. This is a good common circuit for producing a -ve ref voltage from a +ve supply.
tamilselvi	Voltage Inverter	Tuesday, January 19, 2010 10:11:48 AM
Eh guys can i know the o/p waveform of this circuit....
Solo	Voltage Inverter	Sunday, September 20, 2009 12:42:10 PM
Hey, I made this circuit because i need dual power supply for my op amp project. It works BUT the power supply line (+12 V line) now has noise inteference. can anyone give a hint why it happens?
jazzfreak	Voltage Inverter	Monday, June 01, 2009 6:31:07 PM
Some of you who think that this is an inverter that steps up voltage (12v to 120v) should think twice. This is a VOLTAGE or "POLARITY" inverter, which means this circuit switches polarity!
Sean	Voltage Inverter	Thursday, March 26, 2009 12:37:20 AM
Ummmm, power input to the circuit is "V+". Vahid, 13V at 8 amps?!?!?! Damn. If you need about 1 amp, use an LM317. Excellant job on the documentation of the inverter, simple and to the point. Thank you!!!!!!
vahid	Voltage Inverter	Sunday, February 15, 2009 6:53:45 AM
Hi can you help me please. i have 30volt DC and i vant to convert it to 13.5 (8A). i need any circuit design that is helpful.
manny	Voltage Inverter	Thursday, September 18, 2008 3:14:56 AM
where is the connection to power the circuit, sorry can't find it how will it operate without a supply? thanx
Liston of University of Cebu Computer Engineering Dept.(Philippines)	Voltage Inverter(explain)	Monday, August 04, 2008 4:41:28 AM
IC 555 there is only used for oscillation, to have an AC current and the output is connected to transformer to have a higher voltage.