MOSFET selection?

Discussion in 'The Projects Forum' started by mmcap, Aug 16, 2012.

  1. mmcap

    Thread Starter New Member

    Mar 21, 2012
    4
    0
    I am a little overwhelmed by the selection of FETs. If I describe what I would like to make it would be easier to make suggestions. I would like to make is a switch for an audio signal, 1 input signal and pass the signal to output #1 while the switch is in the “off” state, and pass the signal to output #2 while the switch is in the “on” state. Basically the same thing as a single pole duel throw relay. Any suggestions?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    A "typical" MOSFET is an N-channel that requires about 10v on its gate pin (relative to the source pin) to be fully "on". A "logic level" MOSFET allows you to use a lower gate voltage.

    Choose a MOSFET that cites a current spec at least about 4X your expected load. Think of it as cheap insurance. Going large adds very little cost.

    This all said, you'll need something more for switching an audio signal between two poles.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    You could use a MOSFET analog switch, such as the CD4052 (it can switch four stereo inputs).

    Note that it requires a plus and minus supply if you want to switch AC audio signals centered at ground (no DC offset). If you have only a single supply then you would need to offset the audio signal at 1/2 the supply voltage using DC blocking capacitors on the input and output.
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    If using a 4066 analog sw, two sections making a SPDT switch supply control signals for second SPDT analog sw. My quick sketch does'nt look too great but may give you a hint of how it would work-- assuming that input sig. PP is less than Vcc.
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    mmcap and Bernard like this.
  6. mmcap

    Thread Starter New Member

    Mar 21, 2012
    4
    0
    ErnieM I think that is what I have been looking for thank you! And thank you to everyone who took the time to help me!
     
    Last edited: Aug 17, 2012
Loading...