GB760909A - Improvements in or relating to impulse transmitters for telemetering systems - Google Patents

Abstract

760,909. Voltage and current measurements. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. Feb. 22, 1954 [May 6, 1953], No. 18882/55. Divided out of 760,802. Class 37. [Also in Group XL (c)] A circuit for converting a variable direct voltage into a characteristic rate of electrical impulse transmission comprises a capacitance chaiged to an extent corresponding to the instantaneous voltage value, a gas discharge device which becomes conductive when the charge attains a predetermined value, a relay responsive to the conductive conditions to initiate a transmission impulse and complete a discharge circuit for the capacitance and responsive to the extinction of the discharge device to terminate such impulse and disconnect the dis. charge circuit from the capacitance and further capacitance means for maintaining the discharge device conductive for a predetermined period succeeding the initiation of the impulse. The voltage to be telemetered (e.g. the rectified output of a current transformer in an alternator circuit) is connected over terminals 10, 11 to charge capacitance C<SP>1</SP> over resistance R<SP>1</SP> and apply an increasingly positive voltage to the control grid of triode VT<SP>1</SP>, whose cathode is positively biased by potentiometer R<SP>2</SP>, R<SP>3</SP>, R<SP>4</SP> across the H.T. supply 12, 13. Anode current increases until the voltage drop across load resistance R<SP>5</SP> ignites discharge tube VN in shunt therewith to pass an increased anode current sufficient to operate relay F/2. Contacts F<SP>1</SP> close to discharge capacitance C<SP>1</SP> over resistances R<SP>4</SP>, R<SP>6</SP>, contacts F<SP>2</SP> change over to transmit a signalling pulse to a remote station, and F relay - is de-energized, after a time delay im. 2 posed by capacitance C<SP>2</SP> shunting the anode of triode VT<SP>1</SP> to earth, so that the circuit is restored to normal after pulse transmission. Capacitor C<SP>3</SP> shunting R<SP>4</SP> is proportioned so as to neutra. lize the charge on C<SP>1</SP> when contacts F<SP>1</SP> close, and thus to accelerate discharge, while capacitor C<SP>4</SP> inter-connecting the anode and grid of VT<SP>1</SP> reduces by Miller effect the required value of C<SP>1</SP> for the necessary circuit time constant. The interval between the transmitted pulses is inversely proportional to the input voltage and the frequency of the emitted pulse train is directly proportional thereto. Transmission to the receiving station (of the kind described in Specification 760,802) may be by line or radio link.