Found in American documentation from the 1990s, this circuit generates a whistling sound when applied to an amplifier. The power supply must be symmetrical.
This speed or priority switch set uses two LED indicators and two SCRs in a common configuration. The...
Found in a 90s American documentation, this circuit is used in vehicles with contact breaker. The...
This circuit for activating a relay was found in a Radio Electronics magazine from August 1962. The...