This circuit is for old telephones with analog lines. It was found in the May 1988 Radio Electronics magazine. The circuit is powered by the line signal voltaje.
The time the output is high (1) of a TLCSSB in the astable configuration depends on Ra and C. The...
The adjustment of the maximum load voltage is made in the trimpot. The circuit is from 1994...
This circuit from a 1967 documentation generates 2.5 Hz signals depending on the capacitors used,...