We found this circuit in Ferranti's 1974 transistor manual. Transistors are general-purpose types at the time.
This circuit appeared in the July 1969 issue of Radio Electronics magazine. The sensor is an LDR....
For signals up to about 500 kHz modulated in amplitude and transmitted by the power network, the...
This circuit was found in the March 1984 issue of Radio Electronics magazine. The sensor is a...