The sawtooth signal generated by this simple circuit is synchronized with the power line frequency. It is originally designed to control triac circuits but it can be used for other
The supply voltage is highly flexible and can be any level between 4 volt and 36 volts. The values of R1 and R2 are highly dependent on the maximum input voltage.
The best way to obtain the input signal is to connect the input to the power line through indirect means like using an stepdown transformer or a high voltage capacitor.
The first opamp A1 converts the power line sinewave signal into a squarewave signal. This squarewave is further fed to the second opamp which converts it to a sawtooth formed signal.
The opamp A2 functions as a conventional integrator. Its output sinks linearly since a constant current flows through R6 to its non-inverting input.
This integrator is reset to its initial state periodically with
the help of the input signal. The internal design of the opamp makes the integrator react to both positive and negative input signal.
Electronic Circuits volume 1.0 - Circuit Nr. 91
The complete data of the electronic circuit described above can be found in the following book and is available from Amazon.com.
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