This circuit is from a 60's documentation. The circuit uses components from the era and serves to monitor a 150V continuous power line.
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
We find this circuit in American documentation from the 1980s. It consists of a frequency folder...
The frequency of this oscillator can be set in a range from 5000 to 1. We found it in an old...