This circuit with unijunction transistors was found in a documentation from the 80's. The trigger times of the SCRs depend on the capacitors and are adjusted in the 5M (4M7) potentiometers.
This circuit was found in a 73 amateur radio magazine from the 90s. An LED extends the scale from 0...
This sensitive Japanese mid-wave receiver from the 1960s has an output power of 45 mW and is...
This circuit prevents damage by accidentally reversing the power supply polarity. The circuit is...