This circuit was found in an Elektor from the 90s. Next to the circuit we have a table with the delays obtained when the circuit is connected according to the positions of the selector switches.
This circuit was found in Electronics Now, it can be used with universal phones on a common...
B21126E) This circuit was taken from an old Popular Electronics. The circuit can have its...
This circuit has more power than the previous one, since it includes a powerful transistorized stage. The...