GB1171235A - Interconnected Power Supplies - Google Patents

Abstract

1,171,235. Interconnected power supplies. FRIDEN Inc. 9 Oct., 1967 [1 Feb., 1967], No. 46053/67. Heading H3T. Two power supplies feed current through loops which are electrically independent of one another, the supplies being connected by means of a diode and resistor in series across one supply with the junction point connected to one side of the other supply, the diode being forwardly biased by the first supply. In Fig. 1 a driver stage 11, which may be the output stage of an integrated circuit, feeds a switching stage 30 for operating a solenoid 34, e.g. of a print hammer, tape punch, relay or clutch. Each stage has its own power supply 14, 36, the former being earthed at 15 but the latter being floating. Across the supply 14 is a conducting diode 43 and resistor 42, the junction of these being connected to one side of the supply 36. The two supplies are otherwise coupled only through the base-emitter junction of the transistor 30, and switching transients in the latter circuit are not fed back to the earlier stage since changes in the voltages of the two sources do not affect the conduction in the diode 43. This is also unaffected by the turning on and off of the two transistors. A plurality of switching stages 30 may be fed from the same driver stage 11 containing a plurality of transistors 20. The resistor 40 may be replaced by a capacitor. The conductivity types of the transistors may be interchanged, with consequent reversal of the polarities of the supplies and of the diodes 35, 43 (Fig. 2, not shown). The emitter of transistor 30 may be earthed instead of that of transistor 20.