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 circuit, found in a 1992 documentation, uses an uncommon integrated circuit today. With few...
E) Using a CA3130 this preamp has excellent gain. The power supply does not have to be...
The operational amplifier using this 80's circuit is a double 741 of the time. The circuit may be...