An electronic device for producing electric pulses which occur in a random manner and which may be used for drawing lots

摘要

742,305. Pulse generating circuits. STAATSBEDRIJF DER POSTERIJEN, TELEGRAFIE EN TELEFONIE. Dec. 13, 1951 [Dec. 18, 1950], No. 29251/51. Class 40 (6). In a circuit for producing random pulses, the frequency of a pulse generator is varied by applying a voltage or current derived from a fluctuating phenomenon to the generator. A multi-stable state trigger circuit is operated by the pulses to change its state and a switching connection is provided to cause the generator to operate. The recurrence frequency of the blocking oscillator V6 back-coupled over transformer L1, L2 is varied by altering the grid potential of cathode follower V5(1) which varies the cathode potential and thus controls the discharge of capacitor C15. The output from gasfilled triode V1 in a magnetic field is fed over amplifying stages to the grid of the tube V5(1). Depression of the key SSP1/SP applies a paralysing bias to tube V6 through tube V5(1) after a short delay. The switch arm SSP11/SP closes immediately after S1 to allow tube V9 to pass pulses from the trigger pair V7, V8 to a second trigger pair V10, V11, the potential from the anode of tube V11 being used to operate a device. A tertiary winding L3 feeds the grid of cathode follower V5 (11) biased negatively to suppress small pulses which may occur at the time the key S is depressed. The apparatus is stated to be employed in operating a device for drawing lots.