ESP Project 50 Microphone Circuit Test Oscillator

Projects > ESP Project 50 Microphone Circuit Test Oscillator

A portable tone generator that outputs mic level signal can be put to a number of good uses- to make quick work of sorting out long cable runs, troubleshooting cables on the fly, even as a rudimentary test device for your latest preamp build. Using a circuit provided by Rod Elliott of Elliott Sound Products, a DIY tone generator can be both simple to build and affordable.

esp elliott sound products mic test tone generator recording diy audio

Microphone Circuit Test Oscillator Features:

  • Utilizes one dual-opamp (1458, 4558, or LM358)- one stage for the oscillator, the other as an output buffer
  • Oscillation achieved via a simple resistor-capacitor phase shift network; tunable via potentiometer (R1 in the above schematic)
  • Unaffected by phantom power
  • Very low current draw (operates off 9V battery)


  • $20.80 in components, not including enclosure

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One thought on “ESP Project 50 Microphone Circuit Test Oscillator

  1. Since this circuit is not affected by phantom power, is there any way that this circuit could be modified to indicate if phantom power is present?

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