| 摘要 |
1371048 Thyristor circuits ELECTRIC POWER STORAGE Ltd 13 Jan 1972 [14 Jan 1971] 1821/71 Heading H3T [Also in Division G4] A bi-stable circuit comprises a thyristor 11 and transistor 10 in parallel, a relay 15 operated by the thyristor, input pulses at 30 being arranged to fire the thyristor and operation of the relay connecting the input pulse source to the transistor so that the next pulse extinguishes the thyristor. As shown, extinction of the thyristor produces, via a capacitor 38, a positive pulse to operate a next thyristor in a chain of such circuits forming a counter. The contact of the relay may alternatively changeover the pulse input connections from the thyristor to the transistor. Figs. 2-6 (not shown) illustrate variations in the counter. Fig. 2, includes common set and reset lines (60-52) for the stages and an isolating diode 56 to prevent the transistor current maintaining the relay operated. Fig. 3, includes an inverter for each stage to provide an inverted output and Fig. 4, provides changeover switches to select, erect or inverted outputs to permit count up or down. Fig. 5, includes a common input (86) to the stages to complement the count and Fig. 6, includes diode AND and OR gates connected to the stages to indicate all stages at "1" and all at "0". To compare two numbers a pulse train representing the first number is inserted and then complemented. The second pulse train is then fed in. If the numbers are equal the counter will be full and the next pulse will reset the counter to "0". An inhibit transistor (101) may prevent further counting. |
