TUNNEL-DIODE SCALERS,

The principle of operation and characteristics of two pulse counters using tunnel diodes are described. The first is a three-stage binary counter whose input circuit and interstage coupling circuits consist of monostable multivibrators. For each positive pulse, the multivibrators give out two consecutive pulses of opposite polarity. All the tunnel diodes utilized in the circuit are Soviet-made GaAs diodes carrying the disignation 3I30IV. Tests made of an eight-stage counter of the same design showed flawless performance, even at bias voltage variations of 7.0-9.2 v. The maximum counting frequency never fell below 10 Mc. The eighth stage was activated 30 nsec after the appearance of a signal at the counter input. The second pulse counter uses series-connected tunnel diodes which are switched in succession. The output appears after application of a number of pulses at the input equal to the number of series-connected tunnel diodes. The capacitors at the input are necessary for the formation of slow wavefronts which allow sufficient time for the internal capacitances of the diodes to charge up. A threshold element consisting of an emitter follower with TD sub 4 as the load activates the output pulse. The counter performed satisfactorily at bias voltage variations of 6.5-10 v. The maximum frequency of the counter was 10-12 Mc. Author