Make Your Own Tremolo Effects Pedal

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!

Comments

[vadbhoi]

Maybe a power disconnect upon removing input 'jack' would be cool? !

[Teburon]

i don't see where to use the 4.7k resistor.
am i missing something?

[shmelfhelp]

(removed by author or community request)

[oweng4000]

Could I replace r3 with a potentiometer? what would this do?

[spel3o]

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.

[oweng4000]

Thanks. Also, when I built this yesterday there was a noticeable clicking sound and the guitar sounded all distorted. What did i do wrong?

[pyrohaz]

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 :)

RC values:
Resistor: 1k
Capacitor: 10uF

:D that should also add a less harsh tremolo

[Caioa00]

Hey, you didn't say a thing about wave forms or like depth or any other controls. The one and only control in this pedal stands for what?

[spel3o]

The wave form of the tremolo is a DC-square wave, which generates an on-off effect of the guitar. I am still trying to mod it so that the effect is like some one turning the volume up and down, rather than the amp on and off.

[zidakano]

could a capacitor and a bleed off resister be used to release signal over time to create a fade effect. I honestly don't have a clue it  this would work just an idea that popped into my head while reading.

[spel3o]

I was thinking the same thing when I made the pedal, but apparently a sine wave generator would be a lot more complicated than a capacitor and a resistor... Good idea though!

[spel3o]

I've been brainstorming a few options to make something close to a sine/sawtooth wave output of the 555. So far the best theoretical solution is to have two bleed-off resistors immediately before and after a polarized capacitor connected to the output of the 555, both resistors being connected to ground. But seeing as the 555 inverts to negative voltage when off, then the voltages would cancel out... Mabey a window comparator would do the trick... Oh well, worth a try!

[Quercus austrina]

You have the basis for a function generator. See http://www.designnotes.com/downloads/MK105_Assembly.pdf for a function generator from Velleman Kits. Just substitute  the output section from the linked PDF to yours and you can select any output for a variety of waveforms.

Qa

[zidakano]

good link I'll have to keep that in mind whenever I get around to  building some effects.

[zidakano]

So if i understand this right if you used the schematic linked above and connected its out to pin 6 of the op amp and you could have different wave outputs rather than just square.

The schematic linked uses npn transistors so would one of the circuits  have to be converted to work together?

[Quercus austrina]

Just remove your PNP transistor, place the remaining parts in from the other schematic, move your LED1 to the junction at the base of the new NPN transistor labeled T2 and you should be good to go. No need to change anything else.

That will give 4 different waveforms to control the power to the LM386.

Let us know how you fare on the mod.

Qa