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Guitar effects circuit and noise from timing I.C's

Ducados

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I'm trying to create a univibe tyoe of guitar effect. That will consist of a timebase i.c. that will vary the sound to create a tremelo effect and various other phasing sounds. (Variable speed 1 to 30Hz)

The trouble is I can't get it past the breadboard, although it works well enough I cannot avoid the sound of the I.C. switching, whether it be a 4046 VCO, an NE555, hc7417, 4093 or whatever, it just produces a tick, tick, tick in the background.

Even if the IC is not connected to the guitar circuit, the tick sound still persists, even though the guitar circuit only shares the ground connection with the IC.

I suppose I could fix this by putting the IC on another power source and using a vactrol but that would make the project too complicated.

Any suggestions how to reduce this noise?
 

KlausST

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Hi,

Either your schematic is worng or your PCB layout is not suitable.

We don´t know them. So how can we help?

Klaus
 

Audioguru

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The very old NE555 draws a power supply pulse of current each time it switches. It is 400mA(!). A modern LMC555 or TLC555 Cmos IC does not draw massive current pulses like that.
Of you have an unshielded audio wire near a wire with a switching pulse in it then the capacitance between the wires passes the clicks. Audio wires should always be shielded audio cables where the shield blocks interference.
 

stenzer

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Hi,

please provide a schematic of your circuitry and maybe also a picture of your prototype.

greets
 

d123

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Hi,

I suppose a band-stop/reject filter wouldn't help, if the tick is periodic, or the whole circuit wouldn't work any more?

- - - Updated - - -

Hi,

I don't think this is completely related to your issue but maybe something in the thread might inspire a solution or help think through cause of issue...


Popping / Clicking Noise - True Bypass Pedals
 

Audioguru

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It might be something as simple as adding a capacitor across a weak battery that powers the clicker and also powers the audio circuit.
 

danadakk

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When you pick bypass capacitors not all caps are equal in performance for
the same C value. Lower ESR is good. That being said if using LDOs make sure
you use the datasheet recommended min esr value in your cap. Otherwise
go for low esr, like polymer tants. Also use bulk and ceramic in parallel to cover
a broad range of freq and noise on chips.

Polymer-caps-Impedance-ESR-comparization.jpg
 

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