I need to get a transformer that produces 12 watts. Problem is that I burned out the previous 2 I had with my hot wire cutter. I have a couple of 9 watt and 3 watt transformers. Is there anyway I can combine them together so that I can produce the desired 12 watts. I was thinking about rectifying to DC. Then putting the power sources in parallel to power my hot wire cutter. Is this a good idea or is there another way to do it.
no, connecting two transformers together, unless they are identical, doesn't work. The one with the higher voltage will see the others as low impedances and try to drive them, with the result of a burned out transformer. But if you rectify each one to DC, the diodes will prevent the lower voltage ones from overloading the higher voltage one, but you will still have a problem in that the higher voltage one will be the only one delivering any power. .
Get a transformer that is capable of more than the 12 watts your wire cutter needs. It would be more practical. I don't know what current your wire needs, nor the operating voltage. If one assumed 12V., at 12W the current required would be 1 amp. The operating voltage is the critical factor. Overvoltage will be too hot, undervoltage too cool, assuming no form of temperature control. Divide the 12W by the operating voltage to show the current requirement. Get a transformer that exceeds that figure. AC is fine for such a device. You cannot parallel unlike transformers.
It is difficult! (not economical) Transformers work in both directions, it can source and sink. Only transformers designed for series or parallel connections will do! They have to be matched. For your application you need to get the proper transformer. Proper voltage and current rating that is. Hope this properly answers your question Guru
