This old 1 W audio amplifier transistor circuit is from a 1967 Japanese magazine. The transistors are germanium of the time and the type transformers found in similar equipment of the time.
This circuit is used to detect PLL signals from the 4046 IC. The circuit is from an Electronics Now from...
This amplifier or stethoscope with headphone output and using a crystal microphone was found in a...
This circuit uses an 80's operational amplifier. The circuit is from an old RCA manual and can be...