Cook your own distortion article theory help.

[finkfloyd]

Hi,

Ive been reading the article on building your own distortion with either opamps or diodes here http://www.generalguitargadgets.com/richardo/distortion/index.html

But more specifically I have been looking at this part :

The part with the opamp confuses me, looking at the pinout of a rc4558

1 = 1OUT     8 = Vcc+
2 = IN-         7 = 2OUT
3 = IN+        6 = 2IN-
4 = Vcc-       5 = 2IN+

Do both the IN's Pins - 2+6 Get & 3+5 + wired together as it is a dual opamp, or is it working in single channel mode? , and the OUT's etc..?

What is Vcc+ for?

This is a little complex still for me, but I do follow the math on the page still.

I know theres plenty of things to build, But I would like to actually understand how the circuit works. Its frustrating.

Also I built a phase 45 It works fine, I did build it once before, but why do the fets have to be the same and matched for it to phase?

How does one learn that kind of technical stuff, rather than just building tried and tested pre-made layouts?
Ive spent may hours looking at the forum and other sites and I have got better, I didnt know a thing about electronics a few months ago.

I must admit I thought you could make money on pedals, being cheaper to build than buy, well that isnt the case at all, Ive spent a lot of money on this hobby and have only some limited knowledge and a few pedals to show for it.

Orange Treble & Bass Booster
Fuzzface
Phase 45 univibed
Proco Rat
Amp+Cabsim
Tubescreamer
Preamp driver cable + box


Thanks.
Sorry for the long rant

[Nick Ellingworth]

VCC+ and VCC- are the supply voltages; positive (VCC+) and negative (VCC-)

[Bernardduur]

a 4558 is a dual opamp, so you have two opamps for the price of one

[theman]

the rc4558 is a dual op-amp ... meaning that there are two completely independent op-amps inside. pins 1-3 are one op-amp, and pins 5-7 are the other.  they share power. for the diagram you show, you would use only one op-amp. vcc+ and vcc- are the power supplies. these op-amps can run off of +/- supplies. so vcc could be +15, vcc- could be -15V (depends on the op-amp power spec). in most guitar pedals, vcc+ is +9V and vcc- is 0 (gnd).

[finkfloyd]

Hi,

Thanks for the kind replies

Another question if VCC+ & VCC - are the power supply voltages, what are pins 2 & 3 for?

[twabelljr]

    The picture you posted above is just one op-amp. In a 4558 op-amp the pins could be:
pin 1--out                           pin 7--out
pin 2--minus        OR           pin 6--minus
pin 3--plus                          pin 5--plus

pin 8 is 9v +
pin 4 is ground

For it to work you would also need a voltage divider to provide 4.5v through some resistance into the input circuit to pin 3 or 5.
Biasing and powering the op-amp is discussed in the "CYOD" article you are reading.
Look at other schematics of op-amp circuits while you read and it will eventually start to make sense.

[toneman]

All your questions seem to have been answered,
but,    in case U have a few more......

try googling for "rc4558   datasheet"...

U will find lots!! of links to all the info, including pin-outs, package styles, etc etc.
Bout everything U need to know.
Also, look for an "OpAmp tutorial."
Lots os Opamps are pin-4-pin substitutable, and/or "might" change the sound of your project.
stay building
tone

[theman]

Pins 2 and 3 are input of the 1st op-amp. The standard single-ended-output op-amp has two inputs (+ and -) and one output. Pin 2 is the minus input, pin 3 is the + input.  You'll notice that in nearly all practical circuits, the feedback loop around the op-amp connects to the minus terminal for negative feedback.

[finkfloyd]

Hi, Thank you for your time it means a lot, I am eager to try the above, I could do with a nice hardbook to buy really, anyone recommend anything? and i know once you start cooking your own distortion you need an oscilloscope, I have never used one, but im guessing Ill know how to use it when i get it. ((ill learn before, i know the difference between sine/square waves etc..)

Sometimes I ask stupid questions half knowing the answer