Instructables

Simple overdrive effect pedal

This is a very simple overdrive effect. There are a lot of same kind of effects on the net, but I decided to design something simple. It's a great beginner project.

This is me playing with it:
http://youtube.com/watch?v=z-1BsJz9Cpk
First I play clean, the switch on the effect.
 
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Step 2: The schematic

Picture of The schematic
Now it's time to build one for yourself too!

This is what you need:

6.3mm stereo female jack
6.3mm mono female jack
DPDT switch
0.1uF capacitor
LM386 op-amp
220uF electrolytic capacitor
47k resistor
100k resistor
red LED
two 1N4148 diodes

Incase you don't know, how to read schematics, there are a plenty of tutorials available. Just Google
I built the circuit and when I connect it to my guitar, I hear the radio! What did I do wrong?!!
Shielding, enclose the electronics in a conductive material of sorts (faraday cage)
Instead of 1N4148 diodes, could I use 1N5818 schotky diodes? and for the OP amp, should it be an LM386? Can't it be another op amp model?
Something wrong happened, It didn't work and I tried to figure out what happened; I found this, even with the effect on bypass the signal isn't going through; when I unplug the DC power, signal goes through bypassed-effect. This have never happened to me before, can someone explain me what just happened?

Thanks :)
I found that by connecting the diodes to the switch (top right point of the switch) rather than to ground, I get much more distortion. With the circuit as shown above, I get lots of overdrive, but hardly any distortion. Does that make sense?
yrosema1 year ago
I made mine like this:

added drive pot and 2x 1M resistor because it was too loud.
disto2.bmp
badad1 year ago
does it need another kind of jack or the regular will work?
Jahiruddin1 year ago
Dear
Thank you for provide this circuit diagram but now I like to test sound . Is it possible . Please help me.
Jahir
Jahiruddin1 year ago
Dear
Thank you for provide this circuit diagram but now I like to test sound . Is it possible . Please help me.
Jahir
yrosema1 year ago
I read somewhere that if I use a 100uF capacitor in stead of the 0.1uF one I'd get more bass. Is that true?
666sebas9992 years ago
Does it need to be a LM386?
because i get a LM731 from an old recorder, can I use it too?
pfred22 years ago
You had me all pumped up what happened?

T33.jpg
serverfp2 years ago
Como puedo descargar los pdf ayudenme chicos
91chevywt4 years ago
Hey i've got a quick question for you. I've got everything together, as indicated in the diagram, and when I have it hooked up all switching the switch does is amplify the sound almost double. There is no distortion, just loud and clean. Do you have any idea what could be causing this? I checked my resistances with an ohmmeter and they seem to be in line with what the schematic calls for. Other than that i'm not sure what else to try.
Try pins 1 and 8.connect directly or put 10 uF capacitor between pins
Can someone write me schematic for volume pot or gain pot or both of them? Regrets and thanks!
PICKO madjarska stavi pot od 100 k tamo gde ti cika stewa reko!!on je dobar covek slusaj ga!!!al dzabe ti kad nemash lemilicu XD eheheh
Opa!Gde ste Balkanci xD
MGZero3 years ago
I'm curious as to why you have the clipping part in parallel rather than in series.  Wouldn't that cause a short circuit from the capacitor to the switch?  If that's the case then all of the current is going to bypass the diodes and such and then you won't get any distortion.  Can someone confirm this for me?
odopudj MGZero2 years ago
Not really. When u have two directions of current, the current is divided into the two paths.In this case is the way to bypass the less resistance, so there goes more electricity, but also going through the LED.:) (bad eng,sry)
i think you are correct.
MGZero MGZero3 years ago
Nevermind, after doing some research on diodes, I understand what's going on here now.
ski4jesus3 years ago
Just so you know, on my LM386 amp, I have a 10uF capacitor between pin 1 and 8 with a switch and it gives off louder signal and tons of distortion, all the distortion you should need, but im going to try this anyway good job.
oweng40003 years ago
Can I use the image of the clipped and unclipped waveform for a science project I'm doing? Just wanted your permission before I used it.
coolguy20153 years ago
will this work..
shmecker3 years ago
How about adding a 10uF capacitor between 1. pin and 8. pin for some more distortion? Also, adding a switch there is a good idea as far as I am concerned.
Schmidtn4 years ago
Maybe a silly question but, why is it a stereo input jack instead of a mono jack?  Though all guitars were single channel (but I don't know anything about making guitar pedals, so I'm asking). 
magnus0 (author)  Schmidtn4 years ago
 it's actually a power switch. when the input cable is plugged in, the power is turned on, if it's plugged out, it's turned off.
the guitar's mono plug will connect the ring and sleeve on the input plug, this will connect the power.
MGZero magnus03 years ago
That doesn't make sense.  Regardless of whether or not that is connected you're still going to have current draining from the battery through the op amp because of the ground.  The current is going to go through the op amp, drain to ground, and then return to the negative of the battery, which completes a circuit.  You sure this schematic is right?  I'm having quite a few problems with it.
well a batterey doesent drain a lot when u dont comeplete th circut
Crack that baby open and show us the insides. You know just to see how you laid it out.
-Syrus-3 years ago
How about connecting LM386's pin 1 & 8 together? This increases the gain, big time. More disto = more fun ;)
MGZero3 years ago
I accidently grabbed a .01 uF capactiro instead of a .1uF, is this going to cause any major problems?
kgyll3 years ago
 okay... how many volts of the 220uF electrolytic capacitor? and... 6.3mm stereo/mono female jack looks too small... reply to me ASAP
Phosphorus4 years ago
If I use a 0,1 uF electrolythic capacitor, which is the correct orientation? Positive to the left?
 the input from the guitar should go in the positive section. BTW, Where in the world did you find a 0.1 uf electrolytic capacitor?
I think this is a great instructable!!!!  Although- the LED and Diodes section does not have any effect on the circuit....  you can disconnect them and the overdrive still works!!!!
jerrykinda4 years ago
does it work for bass guitar?
Kin04 years ago
do you know how to wire DPDT switch the way he will bypass the battery will be off.
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