Assistance in choosing a replacement MOSFET

Discussion in 'The Projects Forum' started by jgunn, Aug 7, 2012.

  1. jgunn

    Thread Starter New Member

    Aug 7, 2012
    Greetings all,

    I'm building a project from, it's a simple headphone amp that uses a vacuum tube to amplify the input signal and a MOSFET for current gain to drive a set of headphones. I've built audio circuits before, tube circuits mostly, but my theory is a bit weak (I'm learning) and I've not dealt with MOSFETs before. Here's a link to the project page:

    The part called out in the project BOM is a Vishay IRFI510GPBF which is out of stock at Mouser and Digikey. I posted over in their project forum to see if anyone had tried swapping this for another part but it doesn't seem to be an active area, so I'm hoping someone over here can help.

    Looking through the Mouser catalog, I found a Fairchild part that seems to have very similar characteristics. It's EOL, but they still have stock, so maybe that's a decent choice. However, it's not identical and not knowing much about MOSFETs, I'm not sure if it's close enough in all the ways that matter to just work as a drop-in replacement. Here's the alternate part:

    A yes/no answer would be great, but even better would be if someone had the time to explain to me what the relevant stats are for a MOSFET in this type of circuit and why, so I know for next time. :)

  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
    I think you'll find that a irf510 will work, according to the project page. The letters at the end (GPBF) of the part numbers are just changes to the package and the process of making them, engineering changes in the life of the component.
  3. praondevou

    AAC Fanatic!

    Jul 9, 2011
    The replacement part you posted will do it.

    Look for these parameters:
    Drain-Source Breakdown Voltage
    Continuous Drain Current
    Resistance Drain-Source RDS (on)

    If you want it easy choose the same package, through hole and Full-Pak.

    There are several others on digikey.
  4. jgunn

    Thread Starter New Member

    Aug 7, 2012
    Thank you both, I'll give the project a try with an alternate part and see how it goes!