Piezo contact microphone hi-Z amplifier using a FET – Richard Mudhar
High-Z Input Preamps
Amazon.com: DLP Tactical Amplifier/Dynamic-to-Condenser Mic Adaptor Compatible with Low Impedance Peltor Comtac/MSA Sordin Headset to High Impedance PTT/Radio : Electronics
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High-Z Input Preamps
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Make High impedance preamplifier using a transistor | ElecCircuit.com
Toa Electronics M-01F - Microphone Input Module for 900 M-01F
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