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.
In the figure we have an improved method of varying the voltage of a 7812 regulator. The circuit is...
This amplifier operates with a current amplifier for audio distribution lines. The power MOSFET can...
This circuit was found in Popular Electronics from 1992. The circuit has steps determined by...