This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF depending on the generated frequency. Equivalent transistors may be employed.
This circuit is from an English magazine from 1976. By replacing the transistor for a BC548, the...
This old taster circuit, found in 1970s American documentation, is for operatives and comparators of...
This solar cell driven circuit makes 4 LEDs run at a speed given by capacitor C2. The circuit is...