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Here, I will teach you how to make a very simple 1 transistor low power guitar pedal. (I designed the circuit diagram and PCB). This circuit can be ran off old 9v batteries (In version 2, I was running it off a really cheap mobile phone power supply, 5v SMPS) that still have a charge above 1.5v meaning you won't have to throw them out!
Edit: If you increase the input capacito (the 100n capacitor) more bass frequencies can flow through the common emitter amplifier, causing more of the distorted effect.
Also, if you change the bias of the transistor (swap the 100k Resistor for a much higher value, e.g. 680k or more, the transistor will be forced to asymmetrically clip, increasing the distortion. Go to the last page for sound clips :)
In my new circuit, I use a 470k resistor for the bias resistor.
AGAIN! A problem arises at the cost of extra distortion. The attack of the instrument may get chopped off (silenced in this case). With my bass, this only seems to happen when I am using the slap bass technique.
Edit: If you increase the input capacito (the 100n capacitor) more bass frequencies can flow through the common emitter amplifier, causing more of the distorted effect.
Also, if you change the bias of the transistor (swap the 100k Resistor for a much higher value, e.g. 680k or more, the transistor will be forced to asymmetrically clip, increasing the distortion. Go to the last page for sound clips :)
In my new circuit, I use a 470k resistor for the bias resistor.
AGAIN! A problem arises at the cost of extra distortion. The attack of the instrument may get chopped off (silenced in this case). With my bass, this only seems to happen when I am using the slap bass technique.
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Firstly, to make the pedal you obviously need the parts! Most of the parts can be found in the base of a CFL light bulb. I already had the parts to make this and have customised the parts to my liking. In the schematic, it says the input capacitor is 100n. It doesn't matter what value the input capacitor is really aslong as it is within the range of: 47n - 100uF. All the capacitors mainly do is affect the level of distortion at the output (as well as the diodes at the output!). For my transistor, I used a BC337 (On my old one) because I had it at the time but I'm sure that any NPN transistor will work fine. At the output stage, different kinds of diodes produce different levels of distortion. I used simple 1N4001 diodes (The most common diode around) But to get different kinds of output waves, many combinations of diodes exist such as schottky diodes (To produce a lower amplitude giving a nice germanium diode sound due to both germanium and schottky conducting at lower voltages) or rectifier and schottky diodes (Lopsided wave) etc. I tested the input down to 1.5v. at this voltage, it had some quite high distortion and a bit of an annoying hum but worked fine overall. Therefore, a 9v battery would last extremely long is the circuit works down to 1.5v.
The input and output capacitors depict the frequency response of the circuit e.g. The lower the input capacitor, the more bass is cut. This is good if your looking for a nice Trebly overdrive. Otherwise, this capacitor can be increased to any value. The values of these components doesn't particularly matter if your just looking for a simple distortion circuit.
The 100Ohm Resistor that is just above the Diodes can be removed to make the output wave much 'Harsher'.
The 100K resistor at the base of the Transistor mainly depicts the gain. Increasing this resistor increases the gain up to a certain point (It changed the bias of the transistor).
Edit: I have now included my new circuit diagram for the much more RAW! Distortion. Go to the last page for sound samples! Unfortunately, with this new circuit, the distortion isnt so epic at 1.5v :(
For this new circuit, i used a BC337-25, a much more gainier transistor.
The input and output capacitors depict the frequency response of the circuit e.g. The lower the input capacitor, the more bass is cut. This is good if your looking for a nice Trebly overdrive. Otherwise, this capacitor can be increased to any value. The values of these components doesn't particularly matter if your just looking for a simple distortion circuit.
The 100Ohm Resistor that is just above the Diodes can be removed to make the output wave much 'Harsher'.
The 100K resistor at the base of the Transistor mainly depicts the gain. Increasing this resistor increases the gain up to a certain point (It changed the bias of the transistor).
Edit: I have now included my new circuit diagram for the much more RAW! Distortion. Go to the last page for sound samples! Unfortunately, with this new circuit, the distortion isnt so epic at 1.5v :(
For this new circuit, i used a BC337-25, a much more gainier transistor.
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i made it shown in the schematic but still got nothing but a loud buzz/hum sound.
all the resistors were bought new. The transistor, diodes and the black capacitor were all from a dead CFL Light bulb. The 10µf capacitor i found lying round the house.
Can you please please please have a look at my picture to see where i may have gone wrong. (the positive terminal of the battery may look like it is connected to the diodes but it's not, just the bad angle of my camera)
1st: If the CFl light bulb is dead, will the components still work?
and 2nd: can i use a 1000uf polarized capacitor as the input cap?
thanks in advance
Bass > Transistor circuit 1 > Transistor circuit 2 > Output!
Cheers for the q :)
The PLUS side of the power supply gets connected to the schematic where it says "9-15v" and the NEGATIVE side is connected to the schematic where it says "0v"
Thanks :)
Hope that helped :)
thanks
Thanks anyway,I'll try to put some heavy distortion.
The schematic doesn't seem to help me either, as it doesn't seem to coincide with the pictures of your final product. Do you have any "noobed down" steps that I can look at just to get started? All I have in the breadboard at this moment is the input jack (where's the output jack, can I use one?) and the transistor, which in my case isn't even the same transistor.
Also, what's the difference between using an op amp and transistor in this pedal? How much does it change the wiring because of the pins? I have JRC4558D chips lying around, and thought I may be able to kind of mock a tube screamer with the same diodes and op amp. Thoughts or suggestions?
Thanks for any help you could give. It's a lot of fun for how frustrating it all can be.
I am very happy to answer any of your questions. Firstly, do you know the simple electronics knowledge about how transistors capacitors and resistors work? (Im taking it that you do :D).
Right i'll explain the schematic first so you can get to grips with that. In the schematic, the first section that i'll explain is the amplifying section. The transistor in this section is acting as an audio preamplifier, its based on a very simple audio amplifier circuit (miniscule amount of parts) The theory behind this form of amplifier (Class A) can be found all over the internet (I think it would save me typing it all out and repeating stuff, unless of course you want me to!)
The Audio enters through the capacitor (as you can see in the schematic. The input source is the AC wave within a circle, where it says input). it is going through a capacitor to allow the flow of the AC wave (input from guitar) and impede the flow of DC through the transistor. The 100k resistor biases the capacitor positive so the voltage is ~0.7v (The conducting voltage of a standard silicon transistor) The base has to be 0.7v higher than the emitter or it has nowhere to conduct to!
The 10k resistor (at the collector of the transistor) acts as a load resistor and as far as I know is just there to maintain the current between the base-emitter and collector-emitter. The lower this value, the lower base current required to maintain the gain. (this might be a tad to complex to understand lol but im sure you will :D)
Now, hopefully you understand that, if not just think of it as the 'amplifying stage'. After that, there is a capacitor to bias the DC meaning that when the input is 0v, even though on the positive side of the capacitor it may be ~8v, the output will be 0v. such as:
If the swing at the positive side of the capacitor was 0.5v such as: 7.4v to 7.9v, the output at the capacitor will be a 0.5v swing (0.5v to positive and 0.5v to negative). Since the conducting voltage of a silicon diode is 0.7v, the swing will need to be over 0.7v to 'clip' A clipped wave looks like a Sine wave, just with the tops chopped off so they look square-ish. the diodes clip the waveform by abruptly conducting straight to 0v. There are two diodes so they clip to 0v on the negative and positive sides.
I HOPE that has helped you :D any questions, ask away!
When you get time, can you explicitly explain the process of what gets connected to what and how. Like literally physically connected? I'm incredibly confused at why there is only one 1/4" mono jack. How do you take the circuit from that jack to make sure it goes to another jack? Obviously my reason for wanting to do this would be to have a seperate input and output for the guitar>pedal>amplifier.
Sorry to ask so many questions. Thanks for your time.
Sorry about the really crap quality, my phone has the worst camera ever! (I don;t think I will get a HTC again!)
I used input and output mono jacks to simplify it for you :)
Thanks for taking the time to answer.