Found in Popular Electronics from the 90s, this circuit is based on a PLL567 and employs high-end or ultrasonic speakers depending on the frequency of oscillations.
The circuit shown is from the GE semiconductor manual of 1977. In the table we have the values of the...
This circuit for 3.3 V logic circuits has a 5 V input and the maximum output current is on the...
This circuit was found in a 1960s General Electric unijunction transistor manual. The circuit can...