We found this micro amplifier in a technical documentation from National Semiconductor. The circuit can be used on an experimental phone, being powered even by alternative power sources.
This circuit uses opposing MOSFETs operating on a 6 to 15 V input voltage. The circuit is from...
The sensor of this circuit is a photodiode. Equivalent operations can be used, and the instrument can be...
Charcoal microphones are rare today. In the figure we have a circuit that shows the use of one of...