12V to 120V Inverter

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Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how "big" a transformer you use for T1. The inverter can be constructed to supply anywhere from 1 to 1000 (1 KW) watts.

Important: If you have any questions or problems with the circuit, see the forum topic linked to in the Notes section. It will answer all your questions and provide links to many other (and better) inverter circuits.

Schematic

Parts

Part Total Qty. Description Substitutions

C1, C2 2 68 uf, 25 V Tantalum Capacitor

R1, R2 2 10 Ohm, 5 Watt Resistor

R3, R4 2 180 Ohm, 1 Watt Resistor

D1, D2 2 HEP 154 Silicon Diode

Q1, Q2 2 2N3055 NPN Transistor (see "Notes")

T1 1 24V, Center Tapped Transformer (see "Notes")

MISC 1 Wire, Case, Receptical (For Output)

Notes

Q1 and Q2, as well as T1, determine how much wattage the inverter can supply. With Q1,Q2=2N3055 and T1= 15 A, the inverter can supply about 300 watts. Larger transformers and more powerful transistors can be substituted for T1, Q1 and Q2 for more power.

The easiest and least expensive way to get a large T1 is to re-wind an old microwave transformer. These transformers are rated at about 1KW and are perfect. Go to a local TV repair shop and dig through the dumpster until you get the largest microwave you can find. The bigger the microwave the bigger transformer. Remove the transformer, being careful not to touch the large high voltage capacitor that might still be charged. If you want, you can test the transformer, but they are usually still good. Now, remove the old 2000 V secondary, being careful not to damage the primary. Leave the primary in tact. Now, wind on 12 turns of wire, twist a loop (center tap), and wind on 12 more turns. The guage of the wire will depend on how much current you plan to have the transformer supply. Enamel covered magnet wire works great for this. Now secure the windings with tape. Thats all there is to it. Remember to use high current transistors for Q1 and Q2. The 2N3055's in the parts list can only handle 15 amps each.

Remember, when operating at high wattages, this circuit draws huge amounts of current. Don't let your battery go dead :-).

Since this project produces 120 VAC, you must include a fuse and build the project in a case.

You must use tantalum capacitors for C1 and C2. Regular electrolytics will overheat and explode. And yes, 68uF is the correct value. There are no substitutions.

This circuit can be tricky to get going. Differences in transformers, transistors, parts substitutions or anything else not on this page may cause it to not function.

If you want to make 220/240 VAC instead of 120 VAC, you need a transformer with a 220/240 primary (used as the secondary in this circuit as the transformer is backwards) instead of the 120V unit specified here. The rest of the circuit stays the same. But it takes twice the current at 12V to produce 240V as it does 120V.
Check out this forum topic to answer many of the most commonly asked questions about this circuit: 12 - 120V Inverter Again. It covers the most common problems encountered and has some helpful suggestions.

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Comments

PSYCHO 12VDC To 120VAC Inverter Saturday, May 16, 2009 5:53:45 PM

HELLO ALL A SIMPLE CIRCUIT IN THEORY, BUT IF BUILT IT WILL SURELY HAVE DISSAPOINTING RESULTS. IVE NEVER ACTUALLY BUILT THIS BUT ID PROBABLY USE THIS CIRCUIT TO DRIVE A PAIR OF MOSFETS AND SCRAP THE 2N3055S........AN I CERTAINLY WOULD NOT NOT BE POWERING EXPENSIVE APPLIANCES WITH IT

anonymous 12VDC To 120VAC Inverter Thursday, May 07, 2009 2:29:08 AM

procure 4 pcs 240VDC 2200 uF electrolytic capacitors and make a couple of series pairs intended for each base and collectors of C1 and C2.

jamesgonz Circuit simulation Monday, May 04, 2009 1:41:46 PM

I have simulated the circuit on Tina and it does work. It works well enough for me. However, is there someone who could tell me why the capacitors don´t charge and discharge at the same time? The circuit is perfectly symmetrical! I don´t understand why the circuit does work and need to explain it for homework. Thanks in advance. jamesgonz
(Editor's notes: In the real world, not all parts are identical.)

JAMIL 12VDC To 120VAC Inverter Monday, May 04, 2009 11:04:07 AM

Tantalum capacitor?

Man 12VDC To 120VAC Inverter Friday, May 01, 2009 1:18:43 PM

This power inverter was the most worthless thing that I have ever built. Whoever made the schematics on this had NO idea what they were doing. Many things over heated, such as the transistors. The hertz were too high to power anything. So i ended up making my own power inverter that WORKs unlike this worthless piece. Make sure next time before you post something on the internet that it honestly works. Thanks a lot ja
(Editor's notes: Well, you could have avoided all the headaches by reading the warnings at the top of the page and in the notes saying that this circuit doesn't work very well. There are links on this page to a forum topic which covers inverters in great detail and has working schematics as well as corrections to this one.)

donald suaviso 6V DC to 220V AC Tuesday, April 28, 2009 12:01:47 AM

What's up dude..i really want to build an inverter but the schematic on this site is about 12V DC to 120V AC...can you please send me a schematic diagram together with the descriptions of the parts and notes about 6V DC to 220V AC..I will be very thankful and happy if you send me that diagram to my email..I'll be waiting for that dude.. thank you very much!

Fadman 12VDC To 120VAC Inverter Saturday, April 11, 2009 10:46:04 PM

Guys, seriously... Don't keep posting here with simple questions. Just search your local library for books on electronic circuits. It has worked for me for years. P.S. Stop getting frustrated and swearing. Electronics is just a bunch of simple concepts connected in different ways (not hard to understand), seeing as I am only a 14 year old kid. Keep up diligent work and you will figure stuff out (guaranteed).

efren 12VDC To 120VAC Inverter Sunday, April 05, 2009 3:52:11 AM

R1 and R2 heats easily. Based on the circuit, when d1 or d2 conducts the voltage across R1 or R2 is about 11.3 volts which is beyond its maximum voltage based on the formula P=(V*V) / R. When P=5 watts, R=10 ohms, the maximum calculated voltage across R1 or R2 is 7.07 volts. I think this is the reason why R1 and R2 heats easily.

priyalal 12VDC To 120VAC Inverter Saturday, March 28, 2009 2:51:29 AM

Pls brief me how to obtain output AC voltage of 230VAC by changing Q1, Q2 and T1 or related components best regards Priyalal

blared wich 12VDC To 120VAC Inverter Sunday, March 22, 2009 10:51:41 AM

the said inverter circuit doesn't wok.. but am still not sure if there's something wrong with the transformer we use...is there really no substitutions for the tantalum capacitors?

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PSYCHO	12VDC To 120VAC Inverter	Saturday, May 16, 2009 5:53:45 PM
HELLO ALL A SIMPLE CIRCUIT IN THEORY, BUT IF BUILT IT WILL SURELY HAVE DISSAPOINTING RESULTS. IVE NEVER ACTUALLY BUILT THIS BUT ID PROBABLY USE THIS CIRCUIT TO DRIVE A PAIR OF MOSFETS AND SCRAP THE 2N3055S........AN I CERTAINLY WOULD NOT NOT BE POWERING EXPENSIVE APPLIANCES WITH IT
anonymous	12VDC To 120VAC Inverter	Thursday, May 07, 2009 2:29:08 AM
procure 4 pcs 240VDC 2200 uF electrolytic capacitors and make a couple of series pairs intended for each base and collectors of C1 and C2.
jamesgonz	Circuit simulation	Monday, May 04, 2009 1:41:46 PM
I have simulated the circuit on Tina and it does work. It works well enough for me. However, is there someone who could tell me why the capacitors don´t charge and discharge at the same time? The circuit is perfectly symmetrical! I don´t understand why the circuit does work and need to explain it for homework. Thanks in advance. jamesgonz (Editor's notes: In the real world, not all parts are identical.)
JAMIL	12VDC To 120VAC Inverter	Monday, May 04, 2009 11:04:07 AM
Tantalum capacitor?
Man	12VDC To 120VAC Inverter	Friday, May 01, 2009 1:18:43 PM
This power inverter was the most worthless thing that I have ever built. Whoever made the schematics on this had NO idea what they were doing. Many things over heated, such as the transistors. The hertz were too high to power anything. So i ended up making my own power inverter that WORKs unlike this worthless piece. Make sure next time before you post something on the internet that it honestly works. Thanks a lot ja (Editor's notes: Well, you could have avoided all the headaches by reading the warnings at the top of the page and in the notes saying that this circuit doesn't work very well. There are links on this page to a forum topic which covers inverters in great detail and has working schematics as well as corrections to this one.)
donald suaviso	6V DC to 220V AC	Tuesday, April 28, 2009 12:01:47 AM
What's up dude..i really want to build an inverter but the schematic on this site is about 12V DC to 120V AC...can you please send me a schematic diagram together with the descriptions of the parts and notes about 6V DC to 220V AC..I will be very thankful and happy if you send me that diagram to my email..I'll be waiting for that dude.. thank you very much!
Fadman	12VDC To 120VAC Inverter	Saturday, April 11, 2009 10:46:04 PM
Guys, seriously... Don't keep posting here with simple questions. Just search your local library for books on electronic circuits. It has worked for me for years. P.S. Stop getting frustrated and swearing. Electronics is just a bunch of simple concepts connected in different ways (not hard to understand), seeing as I am only a 14 year old kid. Keep up diligent work and you will figure stuff out (guaranteed).
efren	12VDC To 120VAC Inverter	Sunday, April 05, 2009 3:52:11 AM
R1 and R2 heats easily. Based on the circuit, when d1 or d2 conducts the voltage across R1 or R2 is about 11.3 volts which is beyond its maximum voltage based on the formula P=(V*V) / R. When P=5 watts, R=10 ohms, the maximum calculated voltage across R1 or R2 is 7.07 volts. I think this is the reason why R1 and R2 heats easily.
priyalal	12VDC To 120VAC Inverter	Saturday, March 28, 2009 2:51:29 AM
Pls brief me how to obtain output AC voltage of 230VAC by changing Q1, Q2 and T1 or related components best regards Priyalal
blared wich	12VDC To 120VAC Inverter	Sunday, March 22, 2009 10:51:41 AM
the said inverter circuit doesn't wok.. but am still not sure if there's something wrong with the transformer we use...is there really no substitutions for the tantalum capacitors?