Improvements relating to circuits for controlling electromagnetically operated switches

• Main Author: BETTS MAX WILLIAM
• Format: Patent
• Language: English
• Published: 14.10.1964
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; PULSE TECHNIQUE

972,371. Transistor and valve relay circuits. COURTAULDS Ltd. April 13, 1961 [April 14, 1960], No. 13305/60. Headings H3P and H3T. An electromagnetically operated switch having a coil in circuit with an interrupter is operated by utilizing the back voltage generated in the coil when the interrupter is opened as the coil is energized to reset the circuit to the condition it was in prior to the energization of the coil. A rectangular waveform input signal is differentiated by capacitor 8 and resistor 9, and the resulting positive-going impulses are passed by the diode 10 to the base of PNP transistor T 3 to cut it off. The resulting change in collector potential is fed via resistors R 5 , R 6 to the base of transistor T 4 to switch it on completthe resulting back E.M.F. is fed back via resistor ing the energizing circuit to relay coil 1 via R 7 to reset the circuit to its initial state with T 3 interrupter 2. When the coil is energized, conducting and T, cut off. One or both of the interrupter 2 breaks the circuit to the coil and transistors may be replaced by valves.