This circuit is from a 1968 documentation. It makes use of thermistors (NTC) to indicate overheating of charged batteries. Modern equivalent components can be used.
This circuit with only two transistors is from an 80's EDN. It can be implemented with two current...
We found this circuit in the March 1992 Radio Electronics magazine. The circuit provides 100 Hz...
This circuit originally appeared in a publication of 1997. With the changes, the circuit can be...