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

[abyssinianloop]

Thanks for the reply. It turned out that my 470 ohm resister was bad. Once I replaced it, the stutter effect started working more like in your example. The only thing that's still not perfect is the stutter effect is audibly pulsing even when I'm not playing my instrument. I think some other people talked about having that problem too. If I can get that solved I'll be golden.

[abyssinianloop]

This is such a cool sounding pedal and I'm so close to getting it working. The distortion works as well as the gain control and master volume. But when I switch into stutter mode, it only cuts my signal when set to a very slow rate. When I increase the rate, my instrument signal isn't interrupted. And, the fastest rate I can get isn't very fast at all. Anyone have any ideas of what might be wrong?

[Harrymatic]

Your problem sounds like a defective potentiometer on the rate control. Try swapping it for a different one.

[junkyardking]

Any specific reason why you used Linear taper pots as opposed to log pots? Will log taper pots still work? Also, where can I get more info on the wiring between the 9V, board, and DC socket? Is the ground wire running into from the battery, into the toggle, and then onto the board? Sorry if that's a bone head question. I'm just getting into circuits.

[D.A.N]

Followed the strip board diagram twice, still not working, any ideas where i could be going wrong, i'll post pictures if it helps.

[D.A.N]

Hi there, i was wondering if there would be any repercussions if i tried to reduce the size of the circuit by placing things closer together where possible or does the space between components have a relevance to the circuit?

[Harrymatic]

I doubt that there would be any noticeable difference if you were to move components closer. The only reason they are spaced out a bit is so that the stripboard layout is easier to assemble.

[Abbaheart]

Very clever...
I would have never thought of these two chips put together.

[tronicdude6]

what does the second toggle on the back do?

[Harrymatic]

I don't know which one you are talking about, but one turns power on and off and the other enables/disables the stuttering effect, leaving just the distortion.

[trueblue4444]

I tried looking for the capacitors and they seem to have different voltage ratings. Am I supposed to look for a 9v one?

[Harrymatic]

pretty much any voltage capacitor will work for this project.

[veryrandom1]

great instructable it works perfect. but im completely lost on this bypass switch. what is the signal?

[malachipclover]

I used your circuit diagram to attempt building my own pedal, only without the stutter, as I will add that in later, mainly depending on when I can get the parts I need. Everything seems to work fine so far, except there is an annoying high-pitched whining nose no matter what I do. I have a 10uf capacitor between pins 1 and 8, pin 2 is sent to ground, 3 is connected to my guitar cable, 4 grounded, 5 is outputting to a small 8ohm speaker that I am using for testing so I don't accidentely ruin my amp, but I have confirmed the problem was not in the speaker because I have tried plugging into the amp. Pin 6 is connected to the 5v pin on my Arduino Uno until I can get a battery, and all grounds are grounded to the Arduino's ground. Pin 7 is unattached, and there is nothing else in the circuit. No potentiometers, buttons, switches, capacitors (other than the one between 8 and 1), or resistors. I've tried various different combinations of capacitors and resistors both between the LM386 and the audio input, and between the LM386 and the output, but nothing seems to work. Any ideas?

[malachipclover]

Nvm, leave it to me to work hours on something, then once I finally decide to ask for help I find a solution. A 470uf capacitor between pin 3 and the guitar cable did the trick.

[gu1targuy_21]

Do those switches turn the distortion on/off and stutter on/off? can you actually get the stutter alone? or is it always the two together

[TobaTobias]

Great instructable, but which are the effects output/input?

[Harrymatic]

Sorry for not making this clear - the effect input/output is labelled as 'Audio In/Audio Out' on the main stripboard layout diagram.

[TobaTobias]

No worries, thanks mate ;)

[BeerPowered]

Cool stuff! I'm currently building a germanium transistor fuzz face, do you think I could make it stutter with a 555? I just don't like the 386.

[Harrymatic]

This circuit should do the trick - just connect it up to the power rails and the audio line to the output of your fuzz circuit :

[fugyeh]

Can't wait for this little build. Do you think I could use a 556 instead of the 555. A 556 is just 2x 555 basically. Thanks!

[Harrymatic]

It would be absolutely fine, but it would complicate the design a bit, as it has a different pinout to the 555.

[muzzy92]

Do you remember which capacitors you used? I really liked the lack of ticking and noise in your sample and would love to re-create that. I made a working version as well now by the way, so thanks for the guide! Would love some noise-reduction though.

Oh and one more thing I noticed, when I turn the volume on my guitar down to about 50% the guitar doesn't send a signal to the amp anymore, but the noise and ticking of the pedal does get through. I'm not sure if anyone else noticed that or if it's just me.

Thanks!

[Harrymatic]

To be honest, I just crammed in as many small electrolytic and ceramic caps as I could, between power and ground of the NE555 and LM386. I used an assortment of 10uF, 100uF, 47uF, 100nF and 100pF.

I'm afraid I can't answer your question about the guitar volume, as I did all of my main testing using a synthesizer as an audio source - I've only seen this used with a guitar once but I did not hear any problems.

[rsamson1]

So I built this successfully (although I'm having trouble finding proper housing for the project) but I'm still having a bit of trouble with the tremolo effect. Even when nothing is plugged into the input there is a distinctive "pop" or "tremolo tick" that is in time with the rate. Supposedly this is from the 555 timer switching the power, but on your sample there is no popping or ticking.

How do you recommend reducing this?

[Harrymatic]

I recommend fitting capacitors between the power and ground pins of both the LM386 and the NE555 - try 10uF or 100uF to start with.

[muzzy92]

Hello, I tried to make the pedal, but it didn't work, all I got was a working LED, so I decided to make the 2 effects separated to see which one had the fault. I made the stutter effect first (mainly because that's the effect I really want out of this pedal) and all I got was noise. I made it like this: https://www.dropbox.com/s/sz8yynhhtr6osul/schema.png (I'm very sory about the lack of technical drawing skills, but I hope I made it clear enough)

Am I missing something here? Also, I'm having a little trouble understanding how to connect the jacks. Do you connect the pins with the pedal effect, and the grounds to each other?

Besides the jack part, the guide was very clear, so thank you for that! I just lack some soldering skills.

[Harrymatic]

Hi - I've had a look at your diagram. It seems that you've left out the LM386 chip. There isn't really an easy way to separate the two effects - I recommend you build the complete circuit as shown in the stripboard layout, but leave out the 10uF capacitor on the LM386 audio amp, that way you won't get nearly as much gain - so very little distortion.

This is how to wire the jacks :

[muzzy92]

Hey, would it also be possible to make this without the distortion? I already have a distortion pedal so all i want is the stutter effect, can I just follow the schematics and simply ignore the distortion part with the resistors? I'm a beginner when it comes to these kind of schematics so if this is a silly question I apologize!

[Harrymatic]

Hi! It is possible to have this circuit with much less distortion (I think there will always be a little bit). Simply leave out the 10uF capacitor which is between pins 1 and 8 of the LM386. By doing this, the gain factor is reduced from 200 to 20. Then simply turn the gain control nearly all the way down so the signal from your guitar is attenuated.

Unfortunately, without the distortion to mask the noise, the clicks and pops from the signal being turned on and off are more noticeable, but if you are running your own distortion through this effect it may not be a problem.

[fully677]

May be a stupid question, im quite new to all this.

on the stripboard, with the blue lines are they soldered from point to point say with a wire, or is it soldered the whole way across to join the strips?

Sorry I hope that makes sense.

[Harrymatic]

Hi, sorry for the late reply, the wire links are point to point.

[fully677]

not a problem thanks, Ill let you know how I do :)

[Trike Lover]

Very interesting. A long time ago, when I still had a 555 Cookbook, I recall a section on decreasing the cyclic rate on the 555 to well below 1 Hz. I can't find the circuit offhand - I do recall playing with various electrolytic caps and high value resistors. I eventually made a dryer timer based on this, so the delay that was achievable was pretty extreme.

[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.

[J.Reynolds09]

you could try making the enclosure out of wood. Also, I like your idea of the switch to change the capacitance modes. I think when I get the chance to make this I will take that idea even further and use an 8 DIP switch set and put a variety of caps in there to have a truly customizable sound. I think it will be more than interesting to hear what can come from that arrangement. I think I will have to make a small board just for the caps to ride on though.

[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