So i'm a newbie, and with the assistance of my A-Level in electronics step brother we're trying to make a tremolo pedal for guitar. The concept is that an opamp (powered by ±9v) is used as a square wave generator, which will open and close a voltage gated switch which in turn disconnects and reconnects the signal (turns it on and off), at a rate determined by the frequency of the square wave. The circuit below is what i've been using so far.
The issue is that every time the signal cuts out as it's supposed to, there's a loud crack which is what I assume is the shorting of the circuit (the guitar signal, due to 'infinite' current going to ground).
I'm hoping someone has a suggestion how I could resolve this, or alternative suggestions for a voltage gated switch that won't be shorting the circuit. I tried putting the mosfet in series with the guitar signal but this didn't work. If there's a simple way of just getting rid of this crack (which could possibly be solved by softening the edges of the square wave generated resulting in a gradual increase/decrease of voltage above/below threshold potential), this would be hugely appreciated!
Many Thanks, Zach
- EDIT: Representation with output scope of the relaxation oscillator seen here (please copy and paste as doesn't display link nicely): http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+159.55918304990493+60+10+50%0Aa+304+208+400+208+0+9+-9+1000000%0Aw+304+192+304+160+0%0Ar+336+128+384+128+0+100000%0Aw+400+128+400+208+0%0Aw+400+208+400+272+0%0Ar+400+272+304+272+0+100000%0Aw+304+224+304+272+0%0Ar+304+272+240+272+0+100000%0Ag+240+272+240+288+0%0Ac+304+160+240+160+0+0.0000022+0.25657397239391444%0Ag+240+160+240+176+0%0AO+464+208+464+176+0%0A174+304+160+368+128+0+500000+0.005+Resistance%0Aw+384+128+400+128+0%0Af+464+208+512+208+0+1.5+0.02%0Aw+512+224+512+240+0%0Ag+512+240+512+256+0%0Aw+512+192+512+176+0%0AR+512+176+512+144+0+1+450+1.5+0+0+0.5%0Aw+400+208+464+208+0%0Ao+9+64+0+35+0.3125+0.00009765625+0+-1%0Ao+11+64+0+42+0.625+0.00009765625+1+-1%0A