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I mocked up the circuit that eliminates the popping sound heard when the mic button is pressed on a mic cable. However, the signal that the capacitor is attached to, the other terminal to R || Switch to GND, does not go low even when I hold the button down. Essentially, the mic is not muting.

I see, looking around online, that the values used are 100uF and 100Kohm. How do I size the components down? Is this circuit possible with 0.1uF, 150ohms? Mic Mute Pop Eliminating Circuit

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You want a high resistance for the resistor - it is just there to ensure that the capacitor is charged to the average DC voltage on the audio line, so there won't be a "pop" when you close the switch to connect the bottom of the capacitor to ground.

The capacitor must be a fairly high value to present a very low impedance at audio frequencies when the switch is closed. The low impedance of the capacitor effectively shorts the audio signal to ground with the switch closed.

If you don't hear any effect on the audio level when you close the switch, you probably have something wired incorrectly.

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  • \$\begingroup\$ As of right now, the component values are 0.1uF and 150ohms, I'm not sure of the voltage ratings, and this has no effect on the audio level. I'm going to try the larger values again. The other issue I am running into is that the mic detect on the codec only allows up to 375ohms. \$\endgroup\$ – Kay May 3 '17 at 15:33
  • \$\begingroup\$ It is often reasonable to change suggested values in a circuit by 10% or so, but changing values as much as you did totally changes the action of the circuit. \$\endgroup\$ – Peter Bennett May 3 '17 at 15:46
  • \$\begingroup\$ Thanks Peter, that's what I thought too. I may be out of luck if my ceiling is 375ohms. \$\endgroup\$ – Kay May 3 '17 at 16:16
  • \$\begingroup\$ The 100K in the muting circuit has nothing to do with the 375 ohms on the audio line required by the codec. The 375 Ohms shoul be provided by the microphone, or by an added resistor from the audio line to ground. \$\endgroup\$ – Peter Bennett May 3 '17 at 16:27

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