FET coil driver design?

Discussion in 'General Electronics Chat' started by electronice123, Aug 28, 2012.

  1. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    Hi everyone,

    I am trying to drive a HV coil using 2 function generators, a NAND chip (to gate the frequency) and a FET.

    The problem I am having is that the function generators output 5V, the FET is an IRFP450. Reading the datasheet I need at least 10V at the gate to get enough current to drive the coil.

    Can anyone give me suggestions to get this working using the function generators 5V output signals.

    I was thinking of using the function generators to turn on a opto-isolator....The opto isolator would be connected to +10V to drive the FET's gate.
  2. #12


    Nov 30, 2010
    I don't know why you'd need an opto, but you can use it if you want to. It should work if it's fast enough. Plain old bipolar transistors could do the job.
  3. Wendy


    Mar 24, 2008
    Another method is to find a logic level MOSFET, which wold work off of 5V just fine.
  4. electronice123

    Thread Starter Senior Member

    Oct 10, 2008

    Do you know of any logic level FET's that could be used to drive a HV coil? I would want it to have at least 100V protection and be cabable of 10A.

    BTW, the frequency range I'll be working with is 10kHz-100kHz.

    Right now I'm looking at an NTE2987?
    I don't know exactly what to look for other than the gate threshold voltage, the drain current, and the breakdown voltage. All those seem to be in line with what I need.
    Last edited: Aug 28, 2012
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
    Why not use a mosfet driver? The ones from IRF are mostly TTL/CMOS compatible.
  6. Stuntman

    Active Member

    Mar 28, 2011
    +1 Especially if time is key.

    If fast is your goal (which I am assuming it is), decouple your supply rails heavily. Also, I wouldn't be afraid of slamming the gate with 12V to keep it snappy. (although 10V is just fine)

    Just a side note, be prepared to handle the flyback of this HV coil. 500V isn't much when it comes to kickback voltage...