Programmable electronic circuit testing apparatus having plural multifunction test condition generating circuits

Abstract

Abstract 1,198,134. Semi-conductor pulse circuits. INTERNATIONAL BUSINESS MACHINES CORP. 25 Sept., 1967 [10 Oct., 1966], No. 43468/67. Heading H3T. [Also in Divisions G1 and G3] A current summing circuit for use in providing standardized currents in a condition generator for a circuit test apparatus (see Division G1) makes use of individual 5CR controlled circuits 102 (Fig. 3) the SCRs being switched according to programme inputs from a central processor. An SCR e.g. 101-1 when switched in via input diodes drives a transistor 103-1 into saturation to provide a defined current in the precision output resistor 120-1. By switching in suitable combination of the circuits 102 any required total output current can be derived. The SCR's are reset by triggering the transistor 105. Relay 113 controlled by a further programmed SCR controls the output polarity. In a further arrangement for supplying standardized currents, a similar system is used but the transistors 103 are replaced by relays (Fig. 4, not shown). These currents are applied to driver-load circuits, e.g. 71 (Fig. 5b) where they are passed to an output line via a common base amplifier 216, whose base potential is controlled by Zener diode 220. The driver load circuit incorporates a double emitter follower 200, 201 which receives at its input 202 a programmed voltage, so that the output voltage at which the standardized currents are supplied may be controlled. The diode 203 enables fast transitions in drive level to be achieved. Diodes 206, 217 prevent reverse breakdown in the associated transistors. The ferrite cores 209, 224, 225 prevent ringing during fast transients. To avoid excessive power dissipation in the emitter follower transistors, at relatively high base-collector voltages, the supplies to the emitter followers are derived from circuits 80, 81 so as to be varied in accordance with the emitter follower inputs, using an emitter follower 260 whose base voltage is produced across a Zener diode 263 coupled to the input.

Inventors

• 👤 Harold E Jones
• 👤 Friedrich A Karner
• 👤 Ernest H Millham

Bibliographic Details