Distortion Pedal With Stutter Effect

This was built for a friend who asked me for a distortion pedal for him to use with his guitar.The main distortion effect is achieved though an LM386 audio amplifier IC which clips the signal. There is also a stutter effect which turns the output signal on and off at a user-specified rate. This is controlled by one of the three potentiometers (the others control Gain and Output Volume). An NE555 timer IC generates a square wave which turns the amplifier section on and off. The 555 oscillator circuitry and the original idea are based on a design by spel3o.

The stutter effect isn't to everybody's taste, so I added a toggle switch to switch it out of the circuit. A bit of advice - the NE555 timer generates a fair bit of noise and pops on the power supply, so I wired the switch to also remove power from the NE555.

Here's a demonstration video that shows the kind of sound you can get with this:

Step 1 Parts list

The following components and parts were used in this project :

(1x) Die-cast aluminium enclosure - I used the Hammond 29830PSLA
(3x) Potentiometer control knobs
(1x) Heavy-duty latching DPDT push switch
(2x) DPDT miniature toggle switches
(1x) 2.1mm DC power socket (Use a plastic body one if you are using a metal enclosure!)
(2x) 1/4" jack sockets
(1x) 5mm LED bezel
(1x) Battery snap
(1x) PP3 9V battery
(1x) Piece of stripboard
(2x) 8 pin DIL sockets
Various lengths of stranded-core wire

(1x) 10K potentiometer
(2x) 100K potentiometers
(1x) 470R resistor
(1x) 1K resistor
(3x) 10uF electrolytic capacitors
(1x) 220uF electrolytic capacitor
(1x) 0.1uF (100nF) polyester or ceramic capacitor

(1x) 5mm LED of your favourite colour
(1x) NE555 timer IC
(1x) LM386 audio amplifier IC

Comments

[azbo1]

the popping is caused by the signal being disconnected and then reconnected by the foot switch (break before make) to combat the problem you can purchase make before break switches that keep a connection the whole time although they can be harder to get hold of due to the order not being important in many applications

[gnub_daemon]

What if you used a capacitor with two resistor just before the switch to slightly retard the sudden influx of power. Kind of like you would do to get an led to fade in when current is applied and then fade out again when power is removed. Hope that's clear...I'm still kind of new to electronics.

[azbo1]

just thought after posting that last
if this capacitor is between the signal and the ground then it will change the tone of the output
the tone control on a guitar varies the capacitance between the output signal and the ground

[azbo1]

I believe I see what you mean, I think that might work
you would need to make the capacitor (and resistors if necessary) the very last thing that the signal passed through before the output

[Bob939]

Where do the shield terminals on the 1/4 sockets connect to.

[Harrymatic]

to ground, which in this case is the negative terminal of the power supply

[Bob939]

is the stripboard layout shown tracks upward with components on the back?

[Harrymatic]

It's shown component side up - the tracks would not actually be visible. It helps to find the track breaks by poking something thin through the holes and marking off all the breaks with a permanent marker first.

[mrmerino]

What's that bright green thing at the bottom, between the 1K resistor and ground?

[Harrymatic]

That's the power LED which just shows whether the box is switched on or not.

[Falconthrust]

for ghosty37's schematic at the bottom, how are the 3 leads leading to the foot switch wired. i am sort of a noob so can some one explain?

[ghosty37]

it will help you

[ghosty37]

Hy guys.
I've made some little mods on Harrymatic's schematic in order to explain clearly what I mean about the distortion's capacitor selector and the switch between the battery snap and DC Jack.
Hope it could help those who don't understand.

Sorry about the picture's quality, I don't know why, I cant upload it in large size.
If anyone have an idea.
If you cant read it send me a message I'll give the file by mail.

[dog digger]

Instead of a dpdt switch I used a 3PDT switch to make it true bypass.

[Falconthrust]

How do you wire the Mono jacks. I don't understand

[dog digger]

Which ones do you have?

[Alan Victor]

Hello Through this diagram done? For Ghosty37, I can not find the right places for 2 SPDT Interropitores PPDT and hard work, and also the output socket of the battery with the DC adapter. I made a connection here, but I do not know if they are correct.

[ghosty37]

Yeah! I made it to. Realy funny.
I add a little mode, a switch to change the distortion's cap value, a 10nF gives a deep sound who's realy cool with stutter effect, but in distortion, if you reduce gain it produce very strange stuffs.
Thank's for this Instructable. I love DIY guitar effects.

[Harrymatic]

Thanks for the positive feedback and I'm glad the design worked out for you. Would you also care to post photos? I love seeing other peoples interpretations of the designs.

[ghosty37]

Ain't got enclosure for the moment. I dislike plastic boxes, and aluminium ones are more expensive than the system itself.
I'll post pictures when I found it.

Sorry about mistakes I'm frenchy, don't hesitate to correct me, I'm always learning.

[rockdrum]

Are the jack sockets stereo or mono

[Harrymatic]

mono jacks

[dog digger]

Here is the one I built the other day. Awesome pedal!

[Harrymatic]

That is an outstanding pedal you have there! I really like the layout and those wicked cool dials. I also like how you changed the mode toggle switch to a stomp switch. All in all - great work and very well done!
Would you mind posting a picture of inside?

[dog digger]

Thanks. Sure, here is a pic. It's a bit of a mess on the inside and next time I will possibly make everything modular but I works very well. Just a thought, instead of the 555 sending power to the 386 circuit, Why not add a mosfet/transistor to the output of the distortion? No audible pops (hopefully). I will eventually add a stereo jack to the input so that the pedal will not drain any current while nothing is plugged in and someone leaves it on (had it happen before). One last thing, I want to add a DC jack that will disconnect the battery when I plug it in (like any other pedal)

[Harrymatic]

What you have suggested with the transistor may work better than what is already there - but I doubt it would remove the pops completely, as the signal is still being cut off while it is playing - leading to the characteristic pop. To remove them, you'd need to have the circuit fade the audio in and out at very high speeds - and by the time you've done all that you might as well have built a dedicated tremolo pedal. By all means try it though - I can't, as I no longer own my original pedal.

[dog digger]

Do you mind if I post an instructable on my guitar pedal? I will give you credit for the design and the idea.

[Harrymatic]

Not at all - go for it.

[rockdrum]

Where did you get the parts?
Where i looked it was about £35

[Harrymatic]

I already had the little piece of stripboard and the passive components - but the rest came from Bitsbox.co.uk. They have a really nice selection of parts at very reasonable prices and they charge a fixed £1.50 for postage regardless of weight or order size.

[rockdrum]

they were much cheaper thanks

[rockeratr]

How is the foot switch wired to the stripboard? The terminals of the switch in step 4 are connected in a different way than in step 3.

[Harrymatic]

On the stripboard layout it's actually one of the 2 DPDT toggle switches which turns the stutter circuitry on or off. The footswitch is used for the bypass circuitry.

[rockeratr]

I like the looks of this pedal. Nice demo video. What are the dimensions of your casing?

[Harrymatic]

Hammond 29830PSLA - 120mm x 95mm x 34mm

[mdog93]

how much did this cost overall?

[Harrymatic]

About £20.

[MadCobbler]

Can you post a sound sample? I would really like to hear this device before investing the time to build it. I know I could breadboard it, but I don't think I have everything needed on hand.

[Harrymatic]

OK, the video is now up on the introduction step.

[MadCobbler]

Thanks for the video, I understand what is going on now. It is basically a distortion pedal combined with a sharp attack tremolo function and what a crazy range on that occilator!