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LME49710: LME49710 OPamp for guitar pedal.

Part Number: LME49710

Hi there.I am big fan of guitar pedals that is small box can change the guitar sound by analog/digital circuit. I am building the own pedal now. It has no inverting amplifire circuit and clamping circuit to make distortion wave powered by 9V DC, very close to the popular guitar pedal named The RAT. I really want to load the LME49710 on this circuit.But it dosen't work.. When Short the 6 pin to 7 pin only once,OPamp will recovery and works without problem. I guess that some protector function disturbs working on the circuit. Dose anyone know solution?

This is the schematic of The RAT.

www.electrosmash.com/proco-rat

Thank you.

  • Hi,

    Welcome to e2e.
    Could you share your schematic? Or is it the same as the one you're already shared?
    Also let me ask if I understood correctly: you say that the device is not working but by shorting Pins 6 and 7 then the device starts working normally?

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • Mr. Ivan

    Thank you for reply. My schematic is almost same as shared one. I tried to load LME49710 on the original RAT that has absolutely same circuit as shared one, but didn't work. And then shorting pin7 to 6, 2 or 3 makes OPamp work normally every time. I checked DC voltage on each pins of OPamp.

    DC Voltage on each pins
    1:0V
    2:0.9V After shorting changes to 4.3V
    3:0.9V After shorting changes to 4.3V
    4:0V
    5:38mV
    6:0.8V After shorting changes to 4.3V
    7:8.6V
    8:0V


    Best regards.
    Yuichiro
  • Hi Yuichiro,

    It seems that the bias correction performed by the feedback signal on these devices is different, when you short the bias on LME49710 into other pins this seems to take the device out of a kind of stuck state. Perhaps you could look for a device that is more similar to the original one (LM308), you can know if they're similar by the internal schematic diagram or the compensation network (pins 1 and 8).

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators