Found in an Electronic Design from the 90's, this circuit indicates three voltage levels by activating the LED in 3 modes: off, flashing and on for high voltage.
This circuit causes an LED to flash at a frequency determined by the capacitor. The circuit is...
This simple 1-transistor receiver has speaker listening. We found it in an article published in...
The integrated circuit used is equivalent to the 555 and the transistor can be the BC558. R1 and...