This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
This circuit was found in Radio Electronics magazine from October 1964. The circuit uses two...
This 5 V power supply for TTL, Shields and microcontrollers is old, and the components can be...
This automotive alarm uses common components and is suitable for old vehicles. The circuit was...