This QST circuit generates 4 frequency signals according to the crystals used. Transistors admit equivalents although the indicated types can still be found with some ease.
This circuit sounds when the input voltage drops below the value determined by the zener. The...
May 2017 - Mouser Electronics supplies a wide range of sources for LEDs from Mean Well with inputs for...
This 2mA source was found in a 1968’s Philips documentation. The transistor may be the BC549. |...