I want to control AC line(AC220V) with "ON" or "OFF",I want use mosfet to built it, but power mosfet all have inside diode, it can conduct in reverse direction,so it can not control ac source. how can I to design this circuit for ac line switch?
nowhere near enough info for a genuinely useful answer
A Triac is often used to switch AC sources. They are basically two back to back SCRs. Since AC has a zero crossing, when the gate drive is removed, the devices can shut off as they will become reverse biased.
Either way you go, just in case you hadn't thought of it, be sure to include a snubber circuit.
You are looking for a triac.
Put two of them back-to-back in series.
Or put the FET inside a diode bridge.
Either way you're likely to want to use an optically coupled ( and isolated ) control signal.
Graham
if you dont need to use a mosfet try this page,
martin
Note that triacs continue conducting until the current falls to zero though. It takes a polarity reversal for them to switch off. The mosfet doesn't have that 'problem'.
Graham
If what you need to do is control an AC load by another signal, then buy a solid-state relay.
If what you need to do is pass a test, then read the textbook again. :-)
Good Luck! Rich
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