Constant current source (CB20484E)

This circuit uses a current regulator from the 90's. This component is uncommon nowadays. The transistor admits equivalent.

Auto Bias for FET (CB6125E)
This configuration is from a 1964 US documentation valid for any FET. The range of power voltages...
Low voltage detector (CB9685E)
This circuit activates a buzzer when the voltage applied to the input falls below a preset value in...
Intermittent Alarm (CB1514E )
The purpose of the circuit shown in the figure is to open and close the contacts of a relay...