Found in Philips' 1967 documentation, this circuit makes use of period components. The SCR can be of any type, depending on the power of the controlled load.
Found in a Popular Electronics from the 90s, this circuit can act as a transmitter for an audio...
With the circuit shown in the figure, the frequency of a 5 MHz oscillator controlled by crystal can...
This circuit with two HT2030s powers 6 LEDs in a decorative flashing system. The circuit is from...