Circuit Project Electronic

The circuit of Figure 1 produces an accurate, variable-frequency sine wave for use as a general-purpose reference signal. It includes an eighth-order elliptic, switched-capacitor lowpass filter, IC3, which uses a 100-kHz square-wave clock signal that microcontroller IC2 generates. (Any other convenient square-wave source is also acceptable.) The microcontroller receives its clock signal from a 10-MHz oscillator module. A voltage supervisor, IC1, ensures correct operation in the event of a power failure.

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