Many electronic devices depend upon the shape of signals. It is very easy to produce square wave signals from sine wave, but reproducing sinewave signals from square wave is quite difficult. In case of static squarewave-to-sinewave converter, in low frequency range,we can get accurate sine wave, but in high frequency range the shape will not be a true sine wave. This circuit is a solution to that problem.

The circuit shown here uses five Ic’s. The square wave signal is fed at pin of IC1(CD 4024). IC1 is a 7-bit counter, but here is only 6 bits are made use of. The first four bits are fed as a signal bus to IC3(CD 4066) quad bilateral switch through IC2(CD 4077) that contains four exclusive NOR gates. It converts the 4-bit signal bus to ‘up mode’ and ‘down mode’ hexadecimal signals simultaneously. The converted signal bus switches on and off the ladder switches inside CD4066. As a result, the net resistance of ladder varies. This varying resistance varies the charging and discharging currents of capacitor C1in the feedback path of IC5(LM 741). The charging and discharging mode is controlled by IC4 (CD 4011). In fact, capacitor C1 works as an integrator. The sine wave producing circuit needs 64 bit square wave pulse for 360 degree sine wave. A missing pulse in this 64-bit sequence produces a ramp.An astable multivibrator can be used to give the square wave input.

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