This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
This simple timer uses one of the six inverter ports on a CMOS integrated circuit. Rx and Cx...
This circuit can be used as a residential doorbell. We found it in an English publication from...
In the old original version of this circuit from 1989, the LED is common (we recommend 330-ohm...