This amplifier for hearing aid was found in a 1968 documentation using an integrated of the time. The power is from a battery, the consumption of 1.65 mA and the power of about to 1 mW.
This circuit was obtained from General Electric documentation from the 1980s. FET operations are from...
This circuit is from an American documentation from 1976. The FET can be the BF245 or MPF102 and...
This amplifier has a few Watt output, using old transistors. The speaker is 45 ohms, but with...