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Enzo: Behringer Optocoupler info?

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  • #16
    1) I also thought so, but was mistaken.
    Although they are more sensitive to yellow-green (about the same as us), red leds work much better (just test it yourself)
    The explanation is counter-intuitive but logical: our sight is much less sensitive to red than to yellow-green, so red leds are *heavily* doped to be seen at all, and high efficiency ones even much more.
    They swamp the LDR with photons.
    Hands-on experiment supports theory.
    2) I live in Buenos Aires, Argentina, and pay 0.25U$S each, which qualifies as pennies to me , compared to any Vactrol or whatever.
    I buy 200 unit bags straight from the importer/wholesaler.
    I attach a sheet from his catalog.
    He is no Mouser, he sells only to shops or factories.
    In theory they shouldn't sell *me*, but after 41 years in one trade, one gets to know everybody, sort of.

    Juan Manuel Fahey

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    • #17
      Different opto's have different specs, resistances, characteristic curves etc etc. they are not all the same~!

      I have figured out that the Behringer amp is a ripoff of the Ampeg design used in the BA-115 and BA-210 type amps. they Ampeg schematic calls out for a Vactec VTL5C7 opto which has a very specific curve to it. I suspect that the Behringer optos do not follow this same curve and this allows the amp to clip and blow up. I would bet repairing the modules with the correct VTL5C7 opto would make them work better!

      I don't have at 5C7's on had but i have a 5C4 which doesn't quite match. it has a quicker response which may or may not be good. I will try it. and now that i know what the original part was supposed to be. I will purchase some and give them a try.

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      • #18
        Hi zero cool.
        You can get the real stuff here:
        Vactec VTL5C7 :: Optocouplers :: Optoelectronics :: Electronic Parts :: Banzai Music
        Good luck.
        Juan Manuel Fahey

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        • #19
          The 5C4 works but i discovered that what i was seeing is actually 2 different problems! the opto IS limiting the output of the amp, the clipping however is the front end clipping. I put a pot in parallel with the output of the opto so i could experiment with reducing the gain farther then the opto was bringing it down. and what i found is that while the output LEVEL would drop. it was still clipped. So something in the front end was clipping at that point. otherwise further reducing the gain should have brought the output stage out of clipping.

          I will need to study both sets of schematics to see whats going on. but the 5C4 seemed to work ok. better than the stock(bad) opto that I attempted to fix. and I would be curious to compare to the 5C7


          Zc

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          • #20
            I just tried a VTL5C3 in one of these and looking at the output it limits nicely at around 32 volts.

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            • #21
              Originally posted by Davey View Post
              I just tried a VTL5C3 in one of these and looking at the output it limits nicely at around 32 volts.
              Curious as to whether this was a NOS part, or one of the modern repro's like xvive?
              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


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              • #22
                Originally posted by g1 View Post
                Curious as to whether this was a NOS part, or one of the modern repro's like xvive?
                It was an Xvive Enzo.

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                • #23
                  Well, I couldn't think of a more deserving guy to have a part named after him.
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


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                  • #24
                    You know, not far from my old farm house was a road side rest stop, basically a toilet in an outhouse with some parking. It was named for someone, like the J. Fred Muggs rest stop. I forget the real name. I used to wonder if that was really much of an honor to have a roadside toilet named after you.
                    Education is what you're left with after you have forgotten what you have learned.

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                    • #25

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