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What are these good for?

Discussion in 'General Electronics Discussion' started by bigone5500, Sep 30, 2014.

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  1. bigone5500

    bigone5500

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    I scrapped a PCB which had 16 IRF541 N-Channel MOSFETs. They are listed as capable of handling 80v at 25A.

    Can these be used as a solid state relay per-se?
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    It depends. There are several kinds of solid state relays.

    MOSFETs can't switch AC; if you want your SSR to switch AC then you need a bridge rectifier. And it needs to be able to handle the load current.

    MOSFETs require significant gate-source voltage to saturate. If you want isolated drive, you need some way to provide this voltage with isolation. It can be provided by a stack of photodiodes operated in photovoltaic mode, but not with a single optocoupler. It can also be provided by a pulse transformer driven at high frequency.

    Some SSRs provide zero-crossing switching. If you want this feature, external circuitry will be needed.

    To replace a generic SSR with a MOSFET like this, you will need some extra circuitry, and it may be significant.
     
  3. bigone5500

    bigone5500

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    Apr 9, 2014
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Yes, you can do that. You can use them to switch higher voltages too, as long as you provide at least 10V gate-soure voltage.
     
  5. bigone5500

    bigone5500

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    Apr 9, 2014
    LOL! You answered my question as I was asking...this is some good forum software!
     
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