This circuit is temperature stabilized. Modern equivalent transistors can be used, and the power supply can actually be between 9 and 12 V. The circuit is from an old documentation.
This circuit mimics the sound of a siren when we turn the axis of the small DC motor. The...
This sophisticated RPM counter circuit with discrete integrated circuits was obtained in a 1993...
This circuit uses complementary transistors and was found in Mullard's transistor application...