This circuit with TTL compatible output was found in a 1968 US documentation. The circuit is powered by 5 V and the frequency can be changed by changing the crystal.
We found this circuit in an old American publication. The transistors can be BC558 and diode 1N34....
This simple circuit operates with only 1.5 volts of a battery and detects low resistance making a...
The cascade connection of two flip-flops allows division by 4, as shown in the figure. Note that...