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OPA1642: impedance detector circuit - issue can i use opa1642

Sam Mcdonald
Intellectual 330 points
Part Number: OPA1642
Other Parts Discussed in Thread: DIP-ADAPTER-EVM, OPA2134, RC4558, TL072

Hello,

I have on hand 3 OPA1642s.

My Technics SU-V9 is having relay issues, and needs a recap, and possible opamp change. The currenty is AN6552. I can get an adapter for the OPA1642 or any other TI opamp that would suit the circuit.

I took a screen shot of the AN6552 in the speaker circuit.

Thank you

Best Regards

Sam

  • 0 in reply to Sam Mcdonald
    TI__Expert 7320 points
    Hi Sam,
    You might consider the DIP-ADAPTER-EVM (www.ti.com/.../dip-adapter-evm).

    It doesn't look like this amplifier is directly in the audio signal path (though I'm not terribly familiar with the SU-V9), so an audio op amp like the OPA1642 may be overkill here.

    Some op amps will have back-to-back diodes across their inputs, preventing them from being used in a comparator application (as this seems to be). The OPA1642 does not have these diodes, so should work for this application.
  • 0 in reply to Alex Davis
    Intellectual 330 points
    Hello Alex
    Thank you for your reply and help. I can get that adaptor at Mouser. I dont want to waste my OPA1642s, if not in signal path, i used one OPA1642 in my phonostage of my SU-V9. I looked at comparisons, could the OPA2134 be less of a overkill.

    Regards
    Sam
  • 0 in reply to Sam Mcdonald
    TI__Expert 7320 points
    OPA2134 would also be a good choice, but compared to the AN4558 specifications may still be overkill. In this application, you could probably get away with something like a TL072 or other general-purpose op amp. It actually looks like the least expensive option would be a direct replacement, the RC4558. Looks like Digi-key wants $0.39 each for the RC4558 vs. $4.38 each for OPA2134.
  • 0 in reply to Alex Davis
    Intellectual 330 points
    Hello Alex
    Thank you, for mentioning the other choices, great there is still a direct replacement. I had a look again, cant see IC in the signal path. The OPA2134 is actually 6.24aud $.

    Thank you again for the help

    Regards
    Sam