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

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anonymous 12VDC To 120VAC Inverter Sunday, September 27, 2009 7:55:28 PM

i want to make a 3kw inverter so can u place the schematic and i also have a doubt is chainging transformers can solve the problem of increasing wattagw or remaning elements has to be changed?

Homa 12VDC To 120VAC Inverter Saturday, September 26, 2009 5:21:38 AM

well, i think that is a good circuit, considering how it's work...but what about the frequency of the output signal, is it properly to use for daily activity?

anonymous 12VDC To 120VAC Inverter Friday, September 25, 2009 1:14:17 PM

If you wanted to output more juice could't one use mosfets instead of using bjt's? Its easy to find 100 amps or more for a fet but not so easy for a bjt

anonymous 12VDC To 120VAC Inverter Tuesday, September 15, 2009 3:00:27 AM

hi there is it ok to change the tranformer into 220v rather than 120v? coz we use 220v here in philippines..please reply thanks .

anonymous 12VDC To 120VAC Inverter Thursday, September 10, 2009 10:03:49 PM

if you cant build one to bad.i build one in 2 hr frome old tv and microwave anonymous the schematic is good you r a asshole iq 0.5

anonymous 12VDC To 120VAC Inverter Wednesday, August 05, 2009 10:00:17 PM

If a person would add a pot and ne555 timer could you change the frequency of the inverter

anonymous 12VDC To 120VAC Inverter Monday, July 27, 2009 5:43:01 AM

hello... it is very good schematic i think.... i'm making this inverter thses days but i don't know why my inverter don't work.... is there anyone who have specific information and teach me?? i want to make this inverter...

anonymous 12VDC To 120VAC Inverter Saturday, July 25, 2009 1:46:36 PM

Hi, I'm trying to make something like a portable soldering iron and was wondering if it were possible to make an inverter that can run off of a battery pack or small lead acid battery. This would only require about 10 to 15 watts due to its size. For me this is just something to do, a project of sorts, although I don't have any experience building circuits. Everyone has to start somewhere right? thanks

Richard 12VDC To 120VAC Inverter Saturday, July 11, 2009 4:50:20 AM

Hi, I really like your website. I find looking at the circuits is a bit spoilt by all the pointless comments at the bottom though. (like this one.) I know most of them are probably from school kids, but really they should still be able to read around the subject, do a bit of research, read your own comments as to the limitations of the circuits, and post appropriately. Particularly amusing are all the ones that think you're sitting waiting there to instantly design something for them and magic it back to them, or who want you to explain things to them from scratch. If it were me I'd get rid of most of the comments and, if you want to entertain the kids, enhance the explanations. Keep it up. Rich.
(Editor's notes: You would be *amazed* at the ones I don't approve. And just think, I used to get thousands of emails like this per *day*.)

ineedhelp 12VDC To 120VAC Inverter Friday, July 10, 2009 4:15:04 AM

i noly have 68 uf, 50V Tantalum Cap does i matter???

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anonymous	12VDC To 120VAC Inverter	Sunday, September 27, 2009 7:55:28 PM
i want to make a 3kw inverter so can u place the schematic and i also have a doubt is chainging transformers can solve the problem of increasing wattagw or remaning elements has to be changed?
Homa	12VDC To 120VAC Inverter	Saturday, September 26, 2009 5:21:38 AM
well, i think that is a good circuit, considering how it's work...but what about the frequency of the output signal, is it properly to use for daily activity?
anonymous	12VDC To 120VAC Inverter	Friday, September 25, 2009 1:14:17 PM
If you wanted to output more juice could't one use mosfets instead of using bjt's? Its easy to find 100 amps or more for a fet but not so easy for a bjt
anonymous	12VDC To 120VAC Inverter	Tuesday, September 15, 2009 3:00:27 AM
hi there is it ok to change the tranformer into 220v rather than 120v? coz we use 220v here in philippines..please reply thanks .
anonymous	12VDC To 120VAC Inverter	Thursday, September 10, 2009 10:03:49 PM
if you cant build one to bad.i build one in 2 hr frome old tv and microwave anonymous the schematic is good you r a asshole iq 0.5
anonymous	12VDC To 120VAC Inverter	Wednesday, August 05, 2009 10:00:17 PM
If a person would add a pot and ne555 timer could you change the frequency of the inverter
anonymous	12VDC To 120VAC Inverter	Monday, July 27, 2009 5:43:01 AM
hello... it is very good schematic i think.... i'm making this inverter thses days but i don't know why my inverter don't work.... is there anyone who have specific information and teach me?? i want to make this inverter...
anonymous	12VDC To 120VAC Inverter	Saturday, July 25, 2009 1:46:36 PM
Hi, I'm trying to make something like a portable soldering iron and was wondering if it were possible to make an inverter that can run off of a battery pack or small lead acid battery. This would only require about 10 to 15 watts due to its size. For me this is just something to do, a project of sorts, although I don't have any experience building circuits. Everyone has to start somewhere right? thanks
Richard	12VDC To 120VAC Inverter	Saturday, July 11, 2009 4:50:20 AM
Hi, I really like your website. I find looking at the circuits is a bit spoilt by all the pointless comments at the bottom though. (like this one.) I know most of them are probably from school kids, but really they should still be able to read around the subject, do a bit of research, read your own comments as to the limitations of the circuits, and post appropriately. Particularly amusing are all the ones that think you're sitting waiting there to instantly design something for them and magic it back to them, or who want you to explain things to them from scratch. If it were me I'd get rid of most of the comments and, if you want to entertain the kids, enhance the explanations. Keep it up. Rich. (Editor's notes: You would be amazed at the ones I don't approve. And just think, I used to get thousands of emails like this per day.)
ineedhelp	12VDC To 120VAC Inverter	Friday, July 10, 2009 4:15:04 AM
i noly have 68 uf, 50V Tantalum Cap does i matter???