Single Transistor Pre-amplifier¶
Following are pre-amplifier circuit based on a single transistor. Taken from this YouTube video "KF5OBS #49: Microphone Preamplifier".
For Dynamic Microphone¶
I tested and verified working of this circuit with my dynamic microphone.
In original circuit C1 and C2 are 1uF capacitors. I tested and found 10uF capacitors giving better result.
Also, in my initial testing I omitted C3. I got better results after adding it.
Although, I used BC547B. Author told we can use almost any general purpose transistors like 2N2222, 2N3904, etc.
For Electret Microphone¶
It is almost same circuit for dynamic mic, just extra 10k resistor is required to provide power to the electret (condenser) microphone.