This power step for relay activation was found in the 1964 RCA transistors manual. The circuit is of the NF type and the transistors admit equivalents. R4 depends on the drive voltage.
This timer has a divider programmed by BCD switches. The circuit is from a Radio Electronics...
Using a mechanical drive motor, this circuit was found in old documentation. The engine turned off the...
When the input voltage exceeds the value set in R4, the LED lights up, indicating this. The...