This receiver was found in a Japanese publication in 1967. The circuit uses germanium transistors and details of the coils are not given. Power is supplied by a 9 V battery.
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...