Monostable transistor pulse generator with constant pulse width - utilises accurate gating signal to generate transistor current which charges capacitor

The capacitor (C) acquires a charge +IcTr. The capacitor voltage (Vc) is compared with a reference voltage (V2), (=0) in a comparator (12) whose output goes to the reset (R) terminal of a bistable (10). A positive trigger pulse, applied after the end of pulse (Tr) to the set (S) terminal of the bistable causes a pulse of duration (ts) to appear at the output (Q) of the bistable. Pulse (ts), through transistor (T8), acts in a way similar to that of pulse (Tr), allowing a constant current (Id) to flow out of capacitor (C). When capacitor (C) is discharged and its voltage (Vc) = voltage (V1), comparator (12) resets bistable (10) ending pulse (ts). Hence ts = Tr(Ic/Id). Ic:Id = (R4 + R4')/(R3 + R3'), so that ts is independent of capacitance (C), whose precision in an integrated circuit is poor. The circuit is esp. intended for CRT deflection control in a TV receiver. L'INVENTION CONCERNE UN GENERATEUR MONOSTABLE.CE GENERATEUR ETABLIT UN CRENEAU DE DUREE TS DONT LA VALEUR EST PROPORTIONNELLE A CELLE D'UN AUTRE CRENEAU DE DUREE TR APPLIQUE AU GENERATEUR MAIS DONT LA PHASE EST INDEPENDANTE DU CRENEAU TR. LE RAPPORT TSTR EST FONCTION DIRECTE DU RAPPORT DES COURANTS DE CHARGE IC ET DE DECHARGE ID D'UNE CAPACITE C, MAIS IL NE DEPEND PAS DE LA VALEUR DE CETTE CAPACITE. CELLE-CI PEUT ETRE TRES PETITE ET REALISEE EN CIRCUIT INTEGRE SUR UNE TRES FAIBLE SURFACE. ON SAIT, EN CIRCUIT INTEGRE, ETABLIR UN RAPPORT RELATIVEMENT PRECIS ENTRE DEUX AMPLITUDES DE SOURCES DE COURANT.