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 oscillator circuit for sinusoidal audio signals with operational 741 requires a symmetrical power...
Found in a 1974 Radio Shack documentation. This circuit must have a connection to the ground of...
This sensitive circuit detects the live pole of a power grid or outlet. The circuit makes use of a high...