This circuit was found in RCA documentation from the 1980s. The circuit uses LDRs of the time and the 50 uA instrument has zero in the center. R1 and R2 may have 2k2 and R3 10k typically.
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...