GB1223714A - Apparatus for producing a controlled time varying signal - Google Patents

Abstract

1,223,714. Transistor pulse circuits. NATIONAL RESEARCH DEVELOPMENT CORP. 18 July, 1969 [20 May, 1968], No. 23966/68. Heading H3T. [Also in Division G3] A staircase waveform generator comprises a variable rate pulse generator feeding pulses to the waveform generator for producing a stepped output signal of increasing or decreasing magnitude. The pulse generator may comprise a relaxation oscillator including capacitor 38, Fig. 3b, and unijunction transistor 39 feeding pulses to a transistor 40 having a square wave output through a diode pump 42 which charges a capacitor 27, which is discharged through a second diode 44 on application of a reset signal along conductor 33. A buffer amplifier including transistor 45 passes the pump output to a Schmitt trigger circuit including transistors 47, 53 from which the output is taken through a capacitor 55 to a monostable multivibrator 56-58 the output from which is also connected to conductor 33 which output also temporarily holds the Schmitt trigger circuit in the triggered condition through a diode 61, and simultaneously resets the diode pump. The staircase generator may be formed by a bi-stable counting circuit 18, Fig. 2, each section of which may shunt through reed switches 21 one or more of resistors 20 arranged in a geometric series and fed from a constant current source 19. The output of the generator may be applied in series with a thermocouple, measuring temperature, in order to control in an ascending or descending fashion the temperature of a furnace. A sequence generator is also described in the Specification in order that the temperature may be controlled in a number of stages. The Specification envisages the application of a a non-linear pulse rate to the staircase generator in order that the output will be similarly non- linear.