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In this instructable I will show you how to make your own tremolo effects pedal. Really what the pedal is doing is switching the guitar's signal on and off sequentially, ( a DC-square wave generated from a 555 CMOS osclilator pulsates the power to a lm386 audio amplifier amplifying the signal from your guitar.) making that cool effect that we have heard in so many songs to date. For this project you should have a basic idea of soldering and circuits.

Step 1: Materials


As far as tools go you will need:

1.) Soldering Iron

2.) Solder- Make sure that you have rosin core solder, acid core does not work on electronics.

3.) Multimeter (Optional, but very handy)
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Twenty dollars spent at your local Radioshack will get you all of the parts you need for the pedal:

1.) Resistors:     470ohms x 3 (Yellow-Violet-Brown)
                              4.7K x 1 (Yellow-Violet-Red)

2.) Potentiometers:   100K x 1 (the small type that solders onto the board)
                                       1M x1     (the big type that you attach the knob to)

3.) Integrated Circuits:  LM386 Audio Amplifier
                                          555 Timer

4.) Transistors:     PNP Transistor x 1

5.) Capacitors:      10uf Polarized x 2
                                 .1uf Ceramic x 1
                                 220uf Polarized x 1

6.) LEDs:      Green LED x1
                        Red LED x2
                                
7.) Connectors:       Female Guitar Jack x 2
                                   9v Battery Clip x 1

8.) PCB:                Any standard perfboard should do, I used one about the size of a credit card that I                                   bought at Radioshack.

Step 2: The Schematic

This schematic provides the bones of the circuit, but feel free to modify it to your hearts content! R1 controls the volume of the input signal, and R2 controls the rate of the pulses. R3 controls the duration of the pulses. C2 increases the internal gain of the LM386 from 20 to 200. Q1 inverts the -9v signal from the 555 to a +9v signal that oscillates the guitar signal. I didn't add a power switch, but it would be a good addition.  If you have any questions about the design, feel free to comment!

Step 3: Building the Circuit

Before you actually solder, you should test the circuit on a breadboard. What I did was break the circuit down into chunks and test each one (the timer, the transistor, and the audio amplifier). I'm sorry I don't have any photos from the build process, but I wasn't expecting to make an instructable on the project until after I built it.

Step 4: Thank's for Viewing!

I hope this project was of use to you, again if you have any questions, feel free to comment.
So i built it and i can hear the signal running through the pedal but the signal is extremely distorted, accompanied by a tick corresponding with the tremolo rate. Mmmh
<p>Also, what is the max pulse frequency this circuit can produce?</p>
<p>I want to build one of these using a universal CV pedal to control the speed. Is that possible?</p>
just a thot- the 386 is not required. <br> <br>The 555 can easily drive an LED (depending on the LED, add a 100-1K current limiting resistor in series with the LED) Use clear expoxy to glue the LED to an LDR (Light Dependent Resistor - photo resistor) To vary the depth, add a 250K-500K potentiometer in series with the LDR. <br> <br>One major advantage of using an LED is that potential circuit noise is separated from the signal path. Be sure to use a light-proof, metal housing. The LDR can be fooled by outside light and the metal housing will help shield from outside electrical noise. <br> <br>The instrument signal is bridged across the LDR/pot bridge. The effect can be switched on/off with a switch in the 555s battery circuit. You can leave the LED/pot bridge in the circuit or add a footswitch to bypass it. <br> <br>You will be limited to the 555 waveform, but it's a useful effect, especially if you add the potentiometer to vary the depth. <br> <br>Experiment with different color LEDs- LDR are more or less sensitive to various color ranges. <br> <br>having some fun now! <br>-charley
<p>You can also change the waveform with a diode and a pot to duty cycle between 0-99%.</p>
Hello there and thank you for your instructable. I was wondering if you know of a way to also add another pot to control another part of the frequency? Like the wet and dryness. Also is there a way to clean the single up when its in a higher gain? Will adding a higher k resistor between 1 and 8 change and vary that? <br>
so because this has the lm386 in it, presumably you don't need to plug it into an amplifier, just an external speaker?
It depends on how much you'd like to amplify the signal.
how loud would it be without an amp
That depends on what speaker you use, and what gain you have the LM386 sent to.
Ok :P getting beyond my technical knowledge now, without some kind of formula. Thanks for your help. Just another one thing showing my inadequacy of these matters:<br> <br> Does the LM386 N-1 not have a fixed internal gain, or are we talking about the input voltage that matters? Or referring to putting a variable resistor between pins 1 and 8?
The LM386 has a fixed internal gain of 20, but putting a capacitor and variable resistor between pins 1 and 8 you can set the gain up to 200. The higher the gain, the louder the output. From there, you can use an external speaker, but if you want to reduce distortion, you should keep the gain low and use another amplifier. <br><br>spel30 brought up the type of speaker used, and he has a good point. I don't know very much about wattage or speakers, but I know that it at least takes more wattage to drive larger speakers. <br><br>Input voltage does matter, but AFAIK, the LM386 amplifies the signal regardless of how high or low it is. I could be wrong on that one.
what if I want to keep the gain low and use another amplifier? can I use another Lm386? if I do so should I controle the gain or the master. I'm working on this project and there is too mush distortion, I'm thinking to reamplify but I don't know how: https://www.instructables.com/file/F4THFYGGDT4GHE7 <br> <br>https://www.instructables.com/id/Make-a-Sweet-Portable-Guitar-Amp/ <br> <br>Hope you can help me: here is my e-mail if you want: tahalakbir@gmail.com
hey thee have you figured out your problem? let me know, I might be able to help
Yes I knew about the gain matter. Just slightly confusing because I used the Lm386 chip to make an amplifier, here it's being used and still needs an external amplifier. Or does it not need an amplifier but to get least distortion would be best to use an external amp too.
You can use the LM386 as the only amplifier. Using another amp would only allow you to get louder without crazy distortion.
yeah, understood.
How do you control de Depth?
Do you happen to know what type of transistor would work, by any chance?
Hey there. I just made this pedal but it's making a thumping percussive sound that sounds in tune with the pulse rate. Is there anyway to fix this? What might I have done wrong?
That sounds about right, unfortunately. This is a rough design which can be improved on to remove that signal. I'm guessing that a major improvement that can be made would be using a transistor to switch the signal coming out of the 386, instead of turning it on and off (this most likely causes the pop). I had the same problem with mine, it worked though.
Mixed Nuts!
One easy way to add an &quot;automatic&quot; power switch is to use a 1/4&quot; jack on the input with an integral switched leg. Sometimes the only switched jacks available are 1/4&quot; stereo jacks but it doesn't matter - just wire tip and sleeve for your guitar input. <br> <br>The easiest way to add the power switch function is to insert the switched connection in the jack in the negative lead from your battery to the board. (assuming you're not using a wall wart). Then, when you plug in a guitar, the battery negative terminal is connected to the circuit and it powers up. Pull the input plug and it shuts the circuit power off. This isn't my idea - I've seen it documented in about 2 dozen stompbox schematics, but it's sure handy for saving batteries. I think it's also standard in Boss pedals, among others.
I should add here that this is a separate power switch setup than a person would use if installing a power jack for a wall wart that switches between wall-wart power and battery power (wall wart plug in, battery disconnected. If I was including provision for dual power supplies, I'd still put an overall on/off switch in using the guitar input jack.
What is the transistor ?
Hey yall. Just made this pedal, but something must be weird, because I'm not getting any signal in from a guitar, but I am picking up Radio Frequencies... Any ideas?
Hey there! It's likely that you have the ground and signal from your guitar input reversed.
No current limited resistors on the LEDs? I'm surprised they didn't turn into smoke-emitting diodes.....
Hey, I want to make a LFO/ tremolo unit for a modular synthesizer, I was wondering if i could trouble you for a video or MP3 of this thing in action. also, do you know how i could have a different wave form for the lfo, such as a sine or sawtooth instead of a square wave? thanks!
Since this project uses a 555 VCO to control it's output, it will always be using a square wave. To make a sine-wave generator it would require a lot more parts. And I have long since disassembled this project for parts for other projects, I don't think I can get a video up.
Maybe a power disconnect upon removing input 'jack' would be cool? !
What did you use for power? did you use a 9v battery or a 9v wall wart?
To use a wall wart, you would need a voltage regulator in the circuit after the dc power jack. A wall wart, even when it says &quot;9v,&quot; can supply even twice that in little spikes. You might want to google that, I don't know what the fluctuations are like exactly.
Yep. I have bad experience with that now(That comment being a while ago) haha Such as a whole homemade amplifier being fried.
Hey, I am new to electronics. I went to buy capacitors to make this tremolo, but they come in different voltages (16v, 20v). How do you determine which voltage to select?
Hi, You don't need the 386, you could just put the NPN from the signal to earth, and then it will silence it when the NPN input is high. I think...?
That would make a verrrry annoying pop sound with each high and low, probably even higher than the one that already exists.
This is Great!!! good job! ive been looking for something of this type for ages!!
Glad I could help :)
i don't see where to use the 4.7k resistor.<br>am i missing something?
how come R2 doesn't use the 1st pin
Could I replace r3 with a potentiometer? what would this do? <br />
Yes you could, r3 controls the length of each pulse, although the ohm rating on r3 in the schematic is most ideal for a tremelo.<br />
Thanks. Also, when I built this yesterday there was a noticeable clicking sound and the guitar sounded all distorted. What did i do wrong?<br />
Hey :) The distortion was probably because the LM386 was set to having really high gain? an ideal tremolo would have a gain of 1 so the wave was literally on or off and! The clicking I think is just the LM386 being modulated by the 555 timer, if you add a RC filter on the output of the 555 timer, it should reduce the click :)<br /> <br /> RC values:<br /> Resistor: 1k<br /> Capacitor: 10uF<br /> <br /> :D that should also add a less harsh tremolo <br />
When I built this yesterday there was a noticeable clicking sound and the guitar sounded all distorted. What did i do wrong?
dude,what kind of transistor is that on your Tremolo?what I mean is the value or number code....I hope for your reply urgently...tnx..I also have a DIY tremolo effect,almost with the same concept of yours,but I think this one is better,unlike with mine that is emitting a grounded sound when the 555 gives off signal...I just want to know the kind of the transistor...maybe the value of the capacitors too....tnx...<br />
If you go to the step: &quot;the schematic&quot; all of the values are there if you just mouse over the part.<br />
Can you use the regular 555 timer instead of the CMOS&nbsp;version?<br />
A youtube vid or some MP3s would help a lot to decide whether this is close to what I want.&nbsp; I'm looking for a really choppy square wave like this guy gets but I'm also interested in experimenting with much higher switching rates. <style type="text/css"><![CDATA[p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0.0cm; font-size: 12.0pt; font-family: Times New Roman; } a:link, span.MsoHyperlink { color: blue; text-decoration: underline; } a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; } p { margin-right: 0.0cm; margin-left: 0.0cm; font-size: 12.0pt; font-family: Times New Roman; } span.EmailStyle17 { font-family: Arial; } div.Section1 { page: Section1; } ]]></style> <p><span style="font-size: 10.0pt;font-family: Arial;"><a href="http://www.youtube.com/watch?v=t1gQo_ikZ6M" rel="nofollow">http://www.youtube.com/watch?v=t1gQo_ikZ6M</a></span> </p> What kinds of frequency range will this operate at with your default resistor values?<br />

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Bio: All of my life I have been interested in learning the way things work. It was always hard for me to use something and just ... More »
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