This circuit uses an HA2400 consisting of 4 digitally controlled operational amplifiers. The circuit is from a Radio Electronics magazine from March 1980. The power supply must be symmetrical.
Found in an issue of Elektor magazine in the 90s, this battery tester is based on the LM3914. The...
I found this circuit in a July 1982 English magazine. The circuit is still viable by simply using...
This circuit is from a 1966 Motorola Field Effect Transistors Manual. The circuit makes use of...