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12V Trigger Hum - Receiver (pre-out)-->Power Amp

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  • #16
    Originally posted by Adam_M View Post
    Sorry - I should have been clearer. I was intending to use the PE isolator on the trigger cable, not the RCA. Would that device work on the trigger, not input cable? I'm a little concerned about the current capacity of the TI chip as well - but the data sheet did note it can be paralleled for increased capacity. I may do a search and see if there's a higher wattage device (within reason, of course.
    Nope, no passive isolation device will work for the trigger signal since it's DC. Well, except for an old fashioned solenoid relay, but that still needs a separate power supply to switch. That's quite a bit simpler than going for a small solid state device like that TI chip. Sent from my SM-G960U using Tapatalk
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music
    Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat

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    • #17
      Regarding the relay:

      I checked out Digikey for the relays, and applied these filters:
      Manufacturer: Panasonic (simply to narrow the list of hundreds)
      Through hole mounting
      12VDC coil voltage
      Non-Latching Coil
      SPST-NO
      In stock and bulk packaging

      and still got 43 hits. This one seems like it'd work:
      https://www.digikey.com/product-deta...589-ND/1951685
      Is that a reasonable relay for this purpose? Also, I did a bit of reading and there were suggestions to put a diode into the input side of the circuit to prevent DC being fed back into the receiver. For a few cents, is that worth the effort?


      If I'm buying from Digikey, I may just get the TI chip too and see what it does. If I let the magic smoke out, so be it. I'm planning to take some current measurements to see what is actually output. Going tosacrifice a perfectly good 3.5mm cable to do so.

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      • #18
        Look at the signal relays instead, no way you'll need a 10A switch for these. That relay you linked requires 117mA to activate the coil, which may work fine as long as the receiver can put out that much current. A signal relay requires 1/10th the current. Like this bugger:
        https://www.digikey.com/product-deta...7-1-ND/4506449

        Under 12mA of coil current and 2A switch contacts. Typically with relays, a protection diode goes in reverse across the coil to kill back EMF when the relay is deactivated. That will protect your receiver from a voltage spike as the coil de-energizes and breaks down.
        Electronics engineer, woofer enthusiast, and musician.
        Wogg Music
        Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat

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        • #19
          Originally posted by wogg View Post
          Look at the signal relays instead, no way you'll need a 10A switch for these. That relay you linked requires 117mA to activate the coil, which may work fine as long as the receiver can put out that much current. A signal relay requires 1/10th the current. Like this bugger:
          https://www.digikey.com/product-deta...7-1-ND/4506449

          Under 12mA of coil current and 2A switch contacts. Typically with relays, a protection diode goes in reverse across the coil to kill back EMF when the relay is deactivated. That will protect your receiver from a voltage spike as the coil de-energizes and breaks down.
          What he said ...

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