This circuit was found in a 90s Popular Electronics. It is possible to analyze the voltages of an automotive battery. The integrated voltage comparator circuit admits equivalent.
This circuit connected to the input of a good amplifier, with suitable coils can tune stations of medium...
This circuit was obtained in an American documentation of 1975. The transistor can be the BC548, and...
The values of the components of this Mullard (Philips) circuit depend on the desired voltages. The...