This circuit is temperature stabilized. Modern equivalent transistors can be used, and the power supply can actually be between 9 and 12 V. The circuit is from an old documentation.
With the coded activation of the relays, it is possible to control which of the 16 outputs...
The integrated circuit used in this application is not very common. Transistors and resistors...
This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are...