Guitar Synthesizer Using the CD4046

Jul 192017

Guitar Synthesizer Using the CD4046

This guitar synthesizer circuit produces a synthesizer-like sound when used with a guitar. The CMOS PLL CD4046 integrated circuit produces an unusual sound that closely resembles a synthesizer when used with a guitar.

The CD4046 is an integrated circuit consisting of a phase-locked loop (PLL) with a low-power voltage-controlled linear oscillator (VCO) and two phase comparators with a common input signal to the amplifier and a common input to the comparator.

How the Guitar Synthesizer Works

Two of the amplifiers in the CD4007 are used to amplify the signal coming from a guitar. See the diagram.

The phase comparator uses the amplified signal to block the VCO at the frequency of the musical note being played. The VCO will not oscillate until the tone sounds, provided that the low-pass filter shown in the diagram is used. See resistor R3 and capacitor C4.

Guitar Synthesizer Using the PLL CMOS 4046 IC

Increasing the value of resistor R3 causes the VCO to oscillate continuously at approximately one kilohertz without an input signal. This enables smooth transitions between different musical notes.

The base frequency can be adjusted by changing the value of resistor R4.