This 1-transistor circuit for currents up to 50 mA was found in the August 1974 Radio Electronics magazine. The transformer is 50 to 200 mA.
Or integrated circuit used in this circuit two years 80 and little common in those days. The two...
This RF signal meter has a switch position that allows calibration and comparison of low intensity...
This amplifier for old record players has RIAA correction and was found in documentation from the...