Electronic – How to isolate low voltage control circuit from high voltage power circuit

isolationoscillator

Can anyone give me a brief run-down of some methods I could use for this?

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I want to drive a MOSFET or BJT with a 12v 555 circuit or oscillator. The MOSFET will drive a high voltage circuit that can have both large positives and large negatives occuring on both sides of the transistor. As a result, a MOSFET will require a floating voltage divider to ensure the gate isn't destroyed. But that won't ensure that my control circuitry is protected.

I'm pretty sure that I really need to completely electrically isolate the control circuitry if possible. Can anyone throw out some common techniques so I have an idea of ways to go about it? I need this to operate between 50kHz and 800kHz.

Best Answer

That's exactly the application optocouplers are made for.

Optocouplers consist of a LED on one side and a photodiode or a phototransistor on the other side. Both are put into one package but are kept well insulated from each other.

The electrical signal is transformed into light by the LED and back into an electrical signal by the photodiode/phototransistor.

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