Converting DC to AC?

[mattintc]

I cannot wrap my brain around how to do so. I have tried building a chopper out of a relay and all i want is to go from 24VDC to 24VAC. The reason being is because i want to power some contactors and such and got some telephone transformers for free and would love to put them to use instead of having to buy a 24VAC transformer. Iv googled like crazy too! Anyone that can help id more than appreciate it.

[NiHaoMike]

You need an inverter of some sort, like an H bridge connected to an oscillator.

[mattintc]

thank you! finnaly im getting somewheres. This telephone transformer is also 4A rated

[mattintc]

Anymore brains that i can poke at for an idea?

[Rerouter]

as the contactors should not care about it being sine wave driven, the H bridge approach should work just fine,

have an oscillator, divide it down to close to your desired frequency, feed that into not gate to invert for the other channel, then you could then either use a npn with a pullup resistor for each side to switch on and off the respective side, or a high side buffer chip so that it can directly drive the sides at your input voltage,

the whole theory being, part 1 of the cycle, one sides input is high, turning on the npn of the h-bridge and clamping that to ground, while on the other side its pulled low turning on the pnp and clamping the other side to +24V, and for part 2 of the cycle, the process is reversed, resulting in a square wave shaped +-24V waveform which is the same in terms of wattage as a 24V RMS sine wave,

[mattintc]

  wow that was some new terms for me but i got the jist of it all. thank you sir.