Using the 555 and 4020, this timer was found in the July 1994 Radio Electronics magazine. The relay is voltage-dependent, and the transistor is general purpose.
In the figure we have a typical constant current source circuit. Transistor can be equivalent as...
The circuit shown here uses a 4047 to produce three signals whose frequencies are determined by C...
The CA3020 integrated circuit was one of the first commercial types, sold in the 1960s. The...