Simple LED/diode limiter for hottish line level signal?

Discussion in 'General Electronics Chat' started by museumoftechno, May 27, 2015.

  1. museumoftechno

    Thread Starter New Member

    May 27, 2015
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    Hi there

    I've got a custom-built valve distortion unit designed to produce lots of different types of distortion.

    It sounds great (IE seriously great), but it's capable of some really high-level output - I haven't measured it properly, but I think it can produce peaks in excess of +/- 10Vpk. And as a result, I'm underusing it because I'm scared about torching my computer's audio interface.

    Maybe that's over-cautious, but I was wondering if I could adapt this super-simple passive circuit, and just use LEDs to limit the unit's output to about 1.9Vpk? That's a little hotter than line level, but I was hoping it'd avoid shocking the audio interface inputs too much... unless I'd end up just blowing LEDs the whole time?
    [​IMG]

    If anyone's interested, the distortion unit is the "AAE Valve Distortion Unit" on this page: http://tube-electronics.co.uk/

    Thanks!

    Dave
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,656
    632
    If you have a large enough signal (greater than about 4 V P-P) then why not? You can use a divider to reduce the amplitude going into the amplifier if your amplifier has a suitably high input impedance.
     
  3. museumoftechno

    Thread Starter New Member

    May 27, 2015
    3
    0
    Thanks for the reply!

    To be fair the distortion unit has output gain/volume control, but I'd feel better if there was some kind of "fuse" limiter in place just to protect other circuits if I mess up?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,656
    632
    You can get small fuses that blow at low currents but if you choose the right value for the resistor in series with the input to the clipper the fuse would never blow. I think finding a resistor value is more straight-forward than finding the right fuse.
     
  5. museumoftechno

    Thread Starter New Member

    May 27, 2015
    3
    0
    That's great. So I could start testing with sensible volume levels, get a resistor value that sounds good, and gradually turn up the distortion box output?

    Thanks for all your help, really useful.
     
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