555 timer based square wave generator idea.?

Question

I have a small idea, Could it be possible, to generate a square wave using a 555 timer...Then using a transistor, or MOSFET, to amplify the signal, using 120 volts from the wall outlet, so you get a 120 volt high frequency square wave out? There are obvious uses for this, but would it work, and not blow up badly into tiny bits? Or, is there another way of achieving this? The main point of this is to get a "power" square wave, usable on a smaller ferrite core transformer.

Anonymous · Accepted Answer

Yes, you can use the output of a 555 timer to drive the gate of a MOSFET, as long as it is wired as a low-side switch. Your switching time would not be ideal since the 555 probably can't source/sink enough current to overcome the gate capacitance very quickly.

There are plenty of MOSFETS that are rated above 120V. However, please note that the outlet from your wall is AC. In order to make it DC, you would have to rectify it and filter it.

Anyway, be very careful when using power direct from your wall. Also note that FETs often fail short-circuit and will pop you breaker in your fuse box if it fails.

billrussell42 · Answer

Yes, but a few problems. First, when you rectify and filter the 120 volt AC, you get 160 volts DC.

If you take a 200 volt power FET and drive it from the 555, you can get a 160 volt peak to peak AC waveform, but a simple driver as stated would not be suitable for any load. A more complicated circuit needs to be used if you are developing power, and the best is a push-pull circuit operating off of +160 and –160, developing a 320 volt P-P waveform with current limited only by the components. 10 amps would be easy to get. 

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555 timer based square wave generator idea.?

2 Answers