The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
This circuit, obtained from old documentation, allows the recovery of sulfated batteries. The...
This 80's circuit uses a small light bulb as an indicator, but an LED with the appropriate resistor...
This amplifier with the RCA CA3018 integrated circuit was found in the August 1970 issue of Radio...