Oscillators Circuit Diagrams

# 1:800 Oscillator Schematic Circuit Diagram

Oscillators are ten a penny, but this one has something special. Its frequency can
be adjusted over a range of 800:1, it is voltage controlled, and it switches off automatically if the control voltage is less than approximately 0.6 V. As can be seen from the chart, the characteristic curve f = f(Ue) is approximately logarithmic. If the input voltage is less than 0.7 V, T1 and T3 are cut off. The capacitor then charges via the 10-kW resistor. The combination of the capacitor, the two Schmitt triggers and T2 form the actual oscillator circuit. However, T2 cannot discharge the capacitor, because T3 is cut off. In this state, a low level is present at A1 and a high level is present at A2. If the input voltage is increased, T3 starts conducting. This allows the capacitor to be discharged via T2, and the circuit starts to oscillate. If Ue is further increased, the capacitor receives an additional charging current via T1 and the l00-Ω resistor. That causes the oscillator frequency to increase. In situations where the duty cycle of the output signal is not important (such as when the circuit is used as a clock generator), this circuit can be used as a voltage controlled oscillator (VCO) with a large frequency range and shutdown capability.

An oscillator is a mechanical or electronic device that works on the principles of oscillation: a periodic fluctuation between two things based on changes in energy. Computers, clocks, watches, radios, and metal detectors are among the many devices that use oscillators.
Oscillators are essential components that produce a periodic electronic signal, typically a sine wave or square wave. Oscillators convert DC signals to periodic AC signals which can be used to set frequency, be used for audio applications, or used as a clock signal.
Many electronic oscillators work according to the same fundamental principle: an oscillator always employs a sensitive amplifier whose output is supplied back to the input in phase. Thus, the signal reforms and sustains itself. This is associated with positive feedback.

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