This 50% active cycle TTL clock generates signals from 4 to 20 Hz. Its power must be supplied with 5 V and other frequencies can be generated with capacitor replacement.
The configuration shown in the figure is one of the most traditional when it is desired to produce...
The transistors in this circuit from a 1994 technical publication may be BC548 and the 12 V supply...
We found this circuit in a 1977 Radio Shack brochure. Transistors can be the most modern BC548 for NPN...