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Silicon vs. Germanium Difference with flats?

Discussion in 'Effects [BG]' started by bluehevy75, Jul 25, 2019.


  1. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    Just “finished” the BYOC Mouse (Rat Clone). The version with the three way switch for: Silicon-LED-Germanium.

    My problem: The Silicon and Germanium sound the same.

    I am using this pedal for Doom. Also, a Fender P with a 5 string flat wound chrome set (G thrown away) tuned down to “A” standard.

    What seems most likely:
    1. Bad switch?
    2. My bass/set-up/tuning/strings minimizes the differences between these circuits?
    3. Bad construction? (I looked and can’t figure out what, if anything I might have done wrong.

    Thanks. Lousy pic attached.
     

    Attached Files:

  2. Crater

    Crater

    Oct 12, 2011
    Dallas, TX area
    The "LED" setting should be the loudest/most output, then silicon, then Germanium should have the lowest output (because Ge diodes start conducting at a lower voltage than silicon or LEDs). I suspect it just doesn't make that much difference. Maybe you got the Si and Ge diodes mixed up and are running one of each in the two pairs? Ge diodes are usually glass, but Si diodes can be too.

    That can be tested with a multi-meter....

    Most likely answer.

    Does the pedal otherwise work as expected? If so, then I doubt the construction is the issue.

    If your multi-meter has a diode test function, you can test the forward voltage for each diode without removing them from the circuit.
     
  3. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    Thanks Crater. Yes, the pedal works otherwise as expected. The LED is nice and loud the si and ge sound identical and less loud than LED.

    I did not mix up the diodes.

    I will get out the multi-meter. I can follow kit instructions (more or less) but am not skilled enough to know exactly how to test/troubleshoot the components. Hints?

    Thanks again.
     
  4. Crater

    Crater

    Oct 12, 2011
    Dallas, TX area
    To test the switch, put the meter in Ohms (resistance) mode. Measure from the middle terminal on either side. Terminal 3 should be connected to either terminal 1 or terminal 5. Ohm meter should read zero (or very close to zero, less than one ohm) between "ON" terminals. If the switch is off, ohms should be "infinity", most digital meters just show a row of dashes " - - - "

    (1) (2)

    (3) (4)

    (5) (6)




    Diode testing only works if your meter has a diode test function, it may say "diode" or may just have the diode symbol, should look something like this:

    ─►▌─

    With the meter in diode mode, it should read "0.0" when the probes are touched together. I don't know how your pedal is assembled, and whether when you take the cover off if you're looking at the component side or the circuit tracing side. Anyway, with the diode switch in the middle (LED) position, place the probes across the diode leads. The meter should read about:

    0.7 volts for silicon

    0.3 volts for germanium

    I copied this image off BYOC's instructions for the Mouse, they have a nice clear shot of the circuit board, so I've marked the diode's test points with the gray and red arrows.
     
  5. Crater

    Crater

    Oct 12, 2011
    Dallas, TX area
    To test the switch, put the meter in Ohms (resistance) mode. Measure from the middle terminal on either side. Terminal 3 should be connected to either terminal 1 or terminal 5. Ohm meter should read zero (or very close to zero, less than one ohm) between "ON" terminals. If the switch is off, ohms should be "infinity", most digital meters just show a row of dashes " - - - "

    (1) (2)

    (3) (4)

    (5) (6)




    Diode testing only works if your meter has a diode test function, it may say "diode" or may just have the diode symbol, should look something like this:

    ─►▌─

    With the meter in diode mode, it should read "0.0" when the probes are touched together. I don't know how your pedal is assembled, and whether when you take the cover off if you're looking at the component side or the circuit tracing side. Anyway, with the diode switch in the middle (LED) position, place the probes across the diode leads. The meter should read about:

    0.7 volts for silicon

    0.3 volts for germanium

    Maybe this doctored photo will help? Red and gray arrows mark the test points, test and then reverse the black and red test probes, and read again. They should be about the same. Diode test points.jpg
     

    Attached Files:

  6. I don't think the diodes will make much difference in the tone, only the gain level at which it begins to clip will change. You won't notice much difference between 0.3 and 0.7 volts, and 1.3 volts or so for an LED isn't going to be much different, except perhaps 6db more gain before clip. All that can be accommodated with using just a silicon diode and changing the post clip makeup gain.
     
  7. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    Sorry for the late reply. My wife got sick.

    So both sets of diodes read about .8 on either side (didn’t get that .3) with some small variations when switching the test probes for ge.
    Appx: ge:.823-.92 and si: 8.7

    I still didn’t fully track how to test the switch. The picture was super helpful for testing the diodes. Would it be too much to ask to make another one for testing the switch?
     
  8. Crater

    Crater

    Oct 12, 2011
    Dallas, TX area
    I'm going to be a bit lazy and post a link to a You Tube video (that's not me, by the way...) The nice bit is he's testing the same kind of switch that's in your pedal, a DPDT, center off switch. I couldn't explain it any easier than this guy does. The alligator-clip jumper wires are nice to have, they make this sort of testing easier to do and less "fumbly".



    Regarding the voltage measurements of the diodes: those readings are obviously not what's expected for germanium diodes. It appears that both sets are in fact silicon diodes, so that matches the symptoms of "they sound just the same." I suppose it's possible BYOC messed up when they were bagging the parts up for the kit.

    Now the big question - is this a 'deal breaker' for you? GOTTA have the germanium clipping diodes? You might write BYOC and *nicely* ask if they'll drop a couple of germanium diodes in the mail for you. Or procure a couple of them yourself from an electronics supply house. Then you'll have to un-solder the old ones and put the new ones in their place.
     
  9. bluehevy75

    bluehevy75

    Dec 1, 2007
    Chicago, IL
    Right on boss. Thank you so much. That was a big help. It is a SPDT not a DPDT switch but that video helped me figure it out how to test it anyway.

    Attached is a picture of the inside of my pedal. It looks like there a different set of diodes but is it possible that they’re both silicon anyway?

    Not a huge deal if they’re both the same. Just cool to have options.

    55C7AE43-57E4-4D8E-9B81-0079EEC1FF8D.jpeg
     
    Last edited: Aug 15, 2019
  10. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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