GB607306A - Improvements in or relating to sawtooth generators - Google Patents

Abstract

607,306. Saw-tooth generating circuits. PHILCO CORPORATION. Nov. 12, 1945, No. 30192. Convention date, Nov. 11, 1944. [Class 40 (vi)] In a saw-tooth generator, a capacitor is charged rapidly under the control of a triggering signal and discharged slowly through a device, the rate of operation of the discharge device being controlled by the frequency of the triggering signal. The charging and discharging functions may be interchanged. A triggering signal, applied to the square-wave generator 21, Fig. 3, causes thyratron 23 to fire and charge rapidly capacitor 14, the capacitor discharging slowly over the constant current pentode 27. The square wave is also applied to an integrating network 31, 32, the resulting triangular wave-form being rectified by diode 33 and smoothed by resistor-capacitor network 34, 35 to provide a bias for the control grid of pentode 27. An increase in the triggering frequency causes the bias potential to fall and the discharge rate of the capacitor to increase, tending to maintain the sawtooth amplitude constant. In a modification, Fig. 5 (not shown), a further control potential is derived from the voltage developed across the resistor 26 and applied through a D.C. amplifier to the pentode 27. In a further modification, Fig. 6, the main capacitor 14 is charged rapidly by a device 12 under the control of the triggering signal. The rate of operation of the discharge device 16 is varied by the potential developed across capacitor 55 which changes with variations in the triggering frequency. The triggering signal applied to the pulse generator 46 causes thyratron 47 to fire and charge rapidly capacitor 48, the rise in potential across resistor 49 firing thyratron 56 to discharge capacitor 55. Constant current pentode 51 subsequently discharges capacitor 48, the saw-tooth appearing at the anode being rectified by diode 53 to develop the control potential across capacitor 55. In a further modification, Fig. 8, the saw-tooth waveform is fed over cathode follower 63 to a diode 69, the rectified output being mixed with the output from the device 17 and applied to the control grid of pentode 27. The circuit, Fig. 3, may operate as a frequency divider when the switch 28 is near its upper position.