The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and 2N2431 can be used. The circuit is from the 80's and makes use of transformers.
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...