| 摘要 |
1340440 Sawtooth generator COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS CIT - ALCATEL 24 Nov 1972 [24 Nov 1971] 54320/72 Heading H3T In a variable amplitude sawtooth signal generator comprising a differential-input, amplifier 1 with a switch shunted capacitor 2 connected between its output 3 and inverting input 4, the amplitude and frequency of the sawtooth signal are determined by an adjustable potential connected to the inverting input 4 via a resistor 5 and the rate of closing and opening of the switch respectively a fraction of the adjustable potential being applied to the non-inverting input 14 to offset the change in average D.C. level of the sawtooth signal as its amplitude is varied. The switch may be a field-effect transistor 10 controlled by a source 11. The generator may be used in a television camera to produce an artificial zoom effect when viewed on a telephone-video system. The adjustable potential may be obtained by a potentiometer 7 across a voltage supply - V. Resistors 16, 13 divide the adjustable potential for the non-inverting input 14 and preferably divide by a third. |
