This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the indicator is microammeter with zero in the center of the scale.
This experimental AM radio circuit was found in a 1979 English magazine. It can be fitted with a...
This is a variation of the two previous circuits but controlling two LEDs. The brightness of the...
This circuit is the receiver for the CB13997E. The transistor can be the BC548. We also found this...