Sawtooth generator
A sawtooth generator is an electronic signal generator. It supplies a linearly increasing voltage that periodically jumps back to the initial value ( sawtooth oscillation ). For the pixel movement of a television with a cathode ray tube , two sawtooth oscillators are required, through which the horizontal and vertical deflection are taken care of.
functionality
The presented sawtooth oscillator consists of a multivibrator with Q1 and Q2, a constant current source with Q3 and an impedance converter with Q4. Because C3 is charged with a constant current, the voltage across the capacitor increases linearly. C3 is discharged through D1 and the collector-emitter path of Q2. The components C1, C2 and R1 to R4 ensure a multivibrator frequency of 50 Hertz . Because the capacitance of C2 is significantly smaller than that of C1, Q2 conducts significantly less than Q1. While Q1 is conducting, C3 is charged, while Q2 is conducting, C3 is discharged.
Synchronized sawtooth generator
In a television, the sawtooth oscillator is synchronized with the signal from the television broadcaster. The multivibrator has a trigger input for this purpose .
More sawtooth generator circuits
The Miller integrator and bootstrap circuit also allows the generation of a linearly increasing voltage. The oscillating oscillator and blocking oscillator circuit generate sawtooth oscillations that increase in accordance with the charging process of an RC element . The Miller-Transitron circuit uses a pentode to create a freely oscillating sawtooth generator.
literature
- Schröder, Feldmann, Rommel: Electrical communications engineering Volume III . Verlag für Radio-Foto-Kinotechnik, Berlin 1972.