We found this circuit in the 1957 Raytheon transistor application manual. The transistor can be a BC558 and the common 6 V relay, just by using this voltage in the supply.
Hig stability is the main feature of the 10 V regulator circuit shown in the figure and suggested by...
Suggested by Sprague in the 1980s documentation, this circuit can control three-phase AC motors....
This circuit uses a 709 operational amplifier that is no longer common today. However, the same...