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

ananda

12VDC To 120VAC Inverter

Wednesday, May 14, 2008 6:44:40 AM

Thanks for the gem. But, can anyone tell me the substitution for the HEP154 diodes?

anonymous

12VDC To 120VAC Inverter

Wednesday, May 14, 2008 12:12:32 AM

hi all. say for this cct, if i want a variable AC output (ie Vrms=0~230V), can i do that by varying the DC voltage(0~12V)? And what the frequency this AC voltage is? how to change this frequency? How to run this cct in PSpice by the way. Thanks a lot.

senahia

12VDC To 120VAC Inverter

Friday, May 02, 2008 9:28:47 AM

the 68uf,25v tantalum capacitors seem to be very difficult to find , what are best substitutes for the inverters to perform at the same level and HEP 154 SILICON DIODE

Masroor Hussain Alvi

12VDC To 120VAC Inverter

Friday, May 02, 2008 7:48:40 AM

what about the frequency ? and wave ? is its sin wave out put ? or sqr wave ? can we run the fan and t.v ?

acieam

12VDC To 120VAC Inverter

Wednesday, April 30, 2008 11:49:34 PM

hello editor, thanks i learned new important things in electronics and it is not impossible to convert easily a small amount of voltage to a large one..thanks again..

Geoff A Howeth

12VDC To 120VAC Inverter

Monday, April 28, 2008 9:27:16 PM

ok i am having some problems figuring out the 2N3055 NPN Transistor found them ok at radio shack but they only have two pins can someone give me a pinout so i can tell what is the base or emmiter etc...

senahia

12VDC To 120VAC Inverter

Sunday, April 27, 2008 7:14:34 AM

i have a solar panel of 12vdc and i want to connect it to 12vdc to 120vac inverter please who will the circult diagram will be or can you design a diagram for me

liam

12VDC To 120VAC Inverter

Tuesday, April 22, 2008 2:08:14 PM

I built this years ago as one of my first projects. To be honest with the price of inverters now it will be cheaper to buy one. There will also be the added bonus of full peak voltage as comercial units work differently (and the instruction manuals they print have an error usually in them that explains this, mass manufacturing with different stickers = lots of brands with mistake)

anonymous

12VDC To 120VAC Inverter

Sunday, April 20, 2008 1:24:55 AM

how long would you say this invertion would last if the battery wasn't charged? (if say i was running a 600watt laod) in hours...

Demmy

12VDC To 120VAC Inverter

Saturday, April 19, 2008 5:54:04 AM

Infact, this extaly what im i've been looking for, im really happy, thanks

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