This circuit was found in an American magazine 73 for radio amateurs of the 80s. It is an automatic transmission circuit for telegraphy. The circuit is TTL.
We found this circuit in Popular Electronics from 1992. Time is given by C1. The circuit provides an...
A Popular Electronics from the 90's suggests this circuit that is based on a low voltage...
The frequency of a 555 oscillator depends on the capacitance of capacitor C. We can take advantage of...