Simple overdrive effect pedal

Step 2: 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

Comments

[tsamarakoon]

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?

[cardboarddude]

I built the circuit and when I connect it to my guitar, I hear the radio! What did I do wrong?!!

[maheshsankaran]

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?

[Jahiruddin]

Dear
Thank you for provide this circuit diagram but now I like to test sound . Is it possible . Please help me.
Jahir

[Jahiruddin]

Dear
Thank you for provide this circuit diagram but now I like to test sound . Is it possible . Please help me.
Jahir

[666sebas999]

Does it need to be a LM386?
because i get a LM731 from an old recorder, can I use it too?

[pfred2]

You may be able to build one of these:

http://www.google.com/search?hl=en&q=mxr%20distortion%20741%20schematic&gs_sm=e&gs_upl=2229l13479l0l14617l28l28l0l18l7l0l257l1696l0.6.4l10l0&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

[91chevywt]

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.

[odopudj]

Try pins 1 and 8.connect directly or put 10 uF capacitor between pins

[PowerslaveNSHC]

Can someone write me schematic for volume pot or gain pot or both of them? Regrets and thanks!

[Guitar_slave]

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

[odopudj]

Opa!Gde ste Balkanci xD

[MGZero]

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]

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)

[moogbeatz99]

i think you are correct.

[MGZero]

Nevermind, after doing some research on diodes, I understand what's going on here now.

[ski4jesus]

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.

[coolguy2015]

will this work..

[shmecker]

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.

[Schmidtn]

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]

 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]

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.

[mindlesscoolguy789]

well a batterey doesent drain a lot when u dont comeplete th circut

[-Syrus-]

How about connecting LM386's pin 1 & 8 together? This increases the gain, big time. More disto = more fun ;)

[kgyll]

 okay... how many volts of the 220uF electrolytic capacitor? and... 6.3mm stereo/mono female jack looks too small... reply to me ASAP

[alwaysmisternoise]

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!!!!

[Kin0]

do you know how to wire DPDT switch the way he will bypass the battery will be off.

[luudvig]

Hmmm... I only got amplified sound, no overdrive

[adict1234]

Sorry for a dumb question, but how do you ground this stuff? I mean what do you connect the ground units to?

[MilotisX]

every ground connection has to get connected to the negative battery end, everything with three lines (like a pyramid) all has to be connected together basically

[cynical_chemical]

could i use a tda2822 instead of the lm386?

[Agroking]

Hey, Great instructable, But its not that hard to add a potentiometer right about here:

[sev7n]

How would you? Would you ground out one of the three parts that come of the pot?

[Agroking]

of course, one of them is meant to be grounded anyway. That isn't affecting the volume of the output, its affecting the volumeof the input, i.e distortion (it is pre amp.)

[sev7n]

WHat kind of pot would you use? I have a 10K and a 1M but i could get more from radioshack

[1slipperyfish]

hello i've got a 10k pot with a 47uf cat cap on it and all i get is a buzzing noise in the overdrive channel?? ive tried it both ways and still no sound comes through?? when i didn't have it on it worked ok but i couldn't control the volume. also whilst i bothering every one where would i put a second pot for how much distortion i get?? thanks

[reflecta]

maybe its more useful instructable with this i made it in paint :)

[AC DC]

im not good with scematics but i did understand evrything on it but not the input and output wiering, can you take a picture of them?

[magnus0]

i can't take a picture, because i don't have the pedal anymore. basically the input is a stereo plug and the output is a mono plug.

[michoi]

sorry about the noobish question but what does ___ __ _

[madragonn]

does it have to be the exact same model number diode or will any diode do ?

[magnus0]

any diodes will do, you will just get different sound

[madragonn]

thanks :)<br/><br/>and another question, if I used a different Op Amp (for example this one <a rel="nofollow" href="http://commons.wikimedia.org/wiki/File:LM741_Pinout_Square.svg)">http://commons.wikimedia.org/wiki/File:LM741_Pinout_Square.svg)</a> but used the correct pinouts of the LM386 op amp to the pinouts of the LM741 op amp would this circuit still work, and would placing a variable resistor between the gain pins change the sound?<br/><br/>thanks again.<br/>

[rkr]

I'm new to this, but I read up on how to read schematics and I still don't quite understand it, especially where the op-amp is. Any help?

[pyrohaz]

IF you look, the OP amp is the 8 pin chip in the middle. The LM386 is the op-amp, pin 2 (where the guitar signal goes in) is the - input (inverting inpit I think) while the Non inverting input it connected to 0v. All the circuit does is amplify the guitar signal and act like a schmitt trigger, which detects when the wave is positive and negative. When its positive, the output is high, when the wave is negative, the output is low. To get a negative voltage at the output, the OP-amp sinks and sources the capacitor then the clipping happens on the other side :) Hope it helps!

[rkr]

Nice elaboration. I figured it out (hence my other comment below.) Now, seeing as you must know quite a bit more about electrical stuff than I do, could you please tell me how to figure out what type of resistor is needed in a circuit to reduce voltage a certain amount? In my case: from 9v down to 5v. I would be very appreciative.

[magnus0]

It's hard to calculate it using a battery, because battery's amperage may vary. It can output for example 0.2A for 20 hours or 20A fot 1 millisecond.

So let's say you're using an adapter.

You have to check its amperage (in A or mA)

Your voltages:
U1=9v, U2=5V

ohm's law: I (amperes) = U (volts) / R (ohms)

let's say you're adapter's amperage is 0.2A

so: 0.2A=9V/R
R=45 ohms

0.2A=5V/R
R=25 ohms

45-25=20 ohms

I'm not completely sure if all this is right, but you would need a 20 ohm resistor if the amperage of the adapter is 0.2A

[pyrohaz]

Well I assume that for the resistors, your talking about the 47r and 100r in the scematic yes? So at 9v, the current flowing through:
47r = 0.19mA
100r = 0.09mA

So I would have thought that with a lower voltage, the current just had to be matched which would mean the resistors for 5v would be:
47r is changed to 26r (Closest value is 27r)
100r is changed to 55r (Closest is 56r)

Now i think this would work but taking into account magnus's calculations on the power requirements, I think that you could make a compromise. Personally, I dont see why it shouldn't work if you lower the voltage anyway but just to be on the safe side, them values should work

Sorry I didn't read your other comment :)

[rkr]

Thanx for the help, both of you:) Just so you know (as I wasn't specific in my comment above), the 9V reduced to 5V is actually for a pocket-sized iPod charger using a 9V battery that I will be working on soon, which, if created, I may post an instructable on. Thanks again!

[pyrohaz]

Woo! :D Nice well good luck on it! I might have a look when you finished :D

[rkr]

(removed by author or community request)

[rkr]

(removed by author or community request)

[burgess.t2]

i tried to make the footpedal, but nothing seemed to happen? should you solder the components to wires? or onto board? sorry i'm a noob at this sort of stuff but it seemed so interesting =D

[martin_kito]

Can I make this circuit without the DPDT switch??? how??

[misterpyro]

Yeah, you could but then you wouldn't be able to switch to a clean sound. If you wanted too you would have to connect the input directly to the 0.1µF capacitor coming from pin 3 and the 220µF capacitor coming from pin 5 on the LM386. If I read the diagram right. But then you don't have the option to bypass the distortion for a clean sound.

[2plyaudio]

Thanks for the instructable, It worked the first time I jacked in. I messed around with different LEDs, the one I ended up using was white not red. I needed a simple overdrive for recording because my mixer has none built in and this one is so lo-fi, it's got a funky dirt I like. Word.

[livelong]

can somebody teach me how to read this schematic thingy or watever it is?

[godfreyandthandi]

asylum wtf? its simple. im 13 and i understand! anyway thx magnus, im gonna make this in the next week or so. i might post up pix

[hobbles]

How do you make this with out the bypass switch?

[asylum101]

I wish I could understand this to a greater extent than I already do. I would love to do this but I don't quite have the time to research schematics and such. Seems like a really great Instructable.

[ReoTheYokel]

Yeah, same here. Great and yet a very simple instructable. Keep up the good... well... instructables!