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

This is a schematic of the Inverter

Parts
Part
Total Qty.
Description
Substitutions
C1, C2268 uf, 25 V Tantalum Capacitor
R1, R2210 Ohm, 5 Watt Resistor
R3, R42180 Ohm, 1 Watt Resistor
D1, D22HEP 154 Silicon Diode
Q1, Q222N3055 NPN Transistor (see "Notes")
T1124V, Center Tapped Transformer (see "Notes")
MISC1Wire, Case, Receptical (For Output)

Notes

  1. 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.

  2. 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.

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

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

  5. 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.

  6. 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.

  7. 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.

  8. 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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blackcorvo
12VDC To 120VAC Inverter
Wednesday, November 18, 2009 4:53:51 PM
Hello there! I have a little question: I need just 10w of power, because i wanna build a small tube amp and i can't find power transformer for less than 200$. so i wanna build a small power inverter for recticifying the 230v AC to get the B+ I need. What changes i should make in the circuit? is there any other circuits i could try? thanks for any info!
anonymous
12VDC To 120VAC Inverter
Wednesday, November 11, 2009 12:11:48 PM
Hi, I really like this website, and it has helped me in many projects i did. I faced some problems while making this circuit and some compnents has over heated. But i made some corrections and it worked. :) To see the corrections i did please click on this link. http://www.lz500.com/upfiles/Tjr59306.jpg thanks
anonymous
12VDC To 120VAC Inverter
Monday, November 09, 2009 6:47:15 AM
I have 4 nos 12v 9ah sealed battery. How can I use them all to make a 220v invertor. The circuit should also charge the batter when mains are on
emil
12VDC To 120VAC Inverter
Tuesday, November 03, 2009 1:38:46 AM
hai, i have seen this article n have a couple of doubts.. 1. what will be the o/p waveform.. (i think its of sq. wave nature). 2. the o/p frequency? 3.will this circuit be fine to be used with refrigerator if we design it for an o/p of 1000w.? pls do reply me... waiting for your reply, Regards, emil.
LeeLoo
12VDC To 120VAC Inverter
Monday, October 19, 2009 1:24:53 PM
Error in circuit causing C1 and C2 heating up. Reverse the C1 and C2 will solve it . Capacitors can be used any kind of electrolytics type. Makr sure to connect the positive of C1 to Collector of Q1 and do the same for C2.
HENRY
12VDC To 120VAC Inverter
Thursday, October 08, 2009 6:10:36 PM
how can i reduce the frequency of this circuit with out changing the capacitance.....my circuit only show a clean sinusoidal wave when the capacitance is 0.005uF....HELP!!!!
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 .
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