H745 -15V Regulator
The H745 -15V Regulator is one of the DEC standard modular regulators. It can produce an output current of up to 10A at an output voltage of -15V. It has over-current and over-voltage detection and protection.
It was a switching power supply, one of the earliest; however, the basic concept was somewhat different from later supplies of this type. It takes as input AC at a voltage of 20V-30V, runs it through a diode bridge and filter capacitor to convert it to DC. That is then run through a large transistor controlled by a monolithic integrated circuit voltage regulator and an inductor to do VI conversion using a buck converter, to produce the output.
It took its AC input on pins 6 and 8, and it also used +15V input on pins 4 and 5 (why two pins is unclear, since the +15V supply was of limited current); the 15V output was on pin 1, and the ground return on pins 2 and 3. Pin 7 was not connected.