The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and 2N2431 can be used. The circuit is from the 80's and makes use of transformers.
The original purpose of the figure circuit, suggested by National Semiconductor, is to keep the...
The amplifier shown in the figure was obtained from the Anlog Devices linear integrated circuits...
When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very...