This circuit is from an American documentation from the 90's. The SCR can be of any type and the diodes must have current according to the controlled motor.
This power supply with transistor regulation was obtained in a 1995 documentation. The power...
This two-station intercom was found in documentation from 1966. R4 should be experimentally...
We found this circuit in a publication from 1966. The components are from the period. Complete...