This circuit is from a 90's documentation. The circuit is simple, as it uses only two transistors, and the control is done by pressure switches. The indication is done by LEDs.
In this oscillator circuit using 3 TTL inverters we have all the conditions for the frequency...
We obtained this circuit from an old Argentine magazine. The circuit originally uses germanium...
This TTL digital circuit from Texas Instruments documentation from the 1970s used the company's SN types...