This circuit is from a 90s Radio Electronics. The resistors must be precision types and the transistor is a general-purpose type. The operational admits equivalent.
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...