Found in old documentation, this circuit is tuned to pass signals below 245 Hz with a level of 0.044 dB above 500 Hz.
In the figure we have the simple way to use a low current switch or sensor to drive a high power...
This is a VU-meter bargraph with up to 7 LEDs according the Power supply voltage. Adjusts are made by...
This circuit was obtained from a 1990s documentation. The transistor admits equivalent and other...