GB1462105A - Frequency voltage converters - Google Patents

Abstract

1462105 Frequency detectors; transistor switches VDO ADOLF SCHINDLING AG 20 March 1974 [6 April 1973] 12445/74 Headings H3A and H3T A frequency detector in which input pulses are converted into further pulses by charging a capacitor 9 through a first switch 8 and discharging it through a second switch 13, is characterized by the latter switch being an FET. The rising edge of an input pulse 2 turns off transistor 16 allowing capacitor 18 to discharge until the potential across capacitor 18 falls sufficiently for transistor 19 to cut off to turn off transistor 8 and disconnect capacitor 9 from supply +U B . As the potential across capacitor 18 falls still further transistor 20 turns off to turn on FET 13. Capacitor 9 now discharges to produce an output pulse on line 3. When the trailing edge of input pulse 2 arrives, transistor 16 is again turned on and capacitor 18 commences to charge. Transistor 20 is turned on to turn off FET 13 and as the voltage across capacitor 18 rises further, transistor 19 is turned on to turn on transistor 8. Capacitor 9 now charges to produce a further output pulse on line 3. The output pulses are then fed to integrator 4.