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I have been trying to build an inverter (12 volts DC to 120 volts 60 hz. ) by tearing down an old one and trying to copy it. The transformer does not have a number of any kind that I can find. with out tearing this one up how do I find or build one. Any suggestions?

If the inverter is modulating the DC at 60Hz, then most common power transformers [designs]should work. You only need to figure out the turns ratio. You can make a best guess based on the voltages you measure on a working unit or you connect a known AC voltage like 12V and see what you get on the other side.<p>If it modulates at a higher frequency then the core of the transformer might matter. I'm not very sure about that point.

how old is the inverter?How many watts, how big is the transformer?

I picked up the inverter at a garage sale and it is old enough and has been used hard enough that it does not have any info tag or stickers on it any where. I really dont know for sure that it outputs 60hz. it weighs about 15 pounds and puts out 120 volts is all I can really tell.

Chances are, if it is for automotive use it is a 1:10 transformer. Basically a 12VAC transformer turned round. The current rating of this and the transistors in the chopper define the max current at the output.<p>Simplest design would be to chop up the 12V DC into a square wave, pass it through a 1:10 step up transformer and filter until it resembles a sine wave.<p>No reason to think it is not 60Hz output unless you bought it outside the US then it may be 50Hz. design would be almost identical except for the values of the components in the oscillator. <p>Since you're building one yourself, you will probably need an oscilloscope or DMM with frequency measurement to set/verify the oscillator frequency correctly depending on the circuit you use to make this part.

Hmmm if its 15lbs or so...sounds like its an old square wave driven type... tripp lite made a lot of them and still sells them..
but it your looking for somehting...try flea markets.. i see lots of computer back up power supplys for little or nothing..and 99% of the time,,all thats wrong with them is they usually just need batterys
heck i might even have one or 2 transformers laying around here too,,
how many wires are on the transformer you got,,whats wrong with the one you got?
just currious

A really cheap source for inverters are old UPS uninterruptible power supplies with dead batteries. seemingly they are everywhere at free prices, since batteries are expensive, and people want smething new.<p>lots less work than building your own.