#1
im starting some proper pedal building soon (normally i get my more experienced friend to order the parts for me but now hes moved abroad and he isnt going to be contactable for a few weeks) and i was wondering about resistors.

I'm confused with the whole K and R and stuff.

i found a schematic where i need a 4k7 resistor, is a 47KR or a 47R the same, or even similar? im just tryinto work out what all of this means.
#8
you can combine a 400k resister with like a 70k resistor to make a 470k resistor
thats how i made most of my Fuzz Face.
#9
Quote by Gnod
you can combine a 400k resister with like a 70k resistor to make a 470k resistor
thats how i made most of my Fuzz Face.


part values aren't that critical in some places, I think I've got a 470k resistors and 1kohm potentiometer in series for that resistor in my fuzzface (it kind of works as a "more" control for turning the thing up to 11)
#10
hey thanks guys, thats all really helpful, how about the deal with capacitors and the whole U and UF and P things and can someone tel me what caps i have to use in this http://aronnelson.com/gallery/album19/mxr_dist_plus?full=1 and if there is a different IC (i think the big block is an IC) that i can use.

Thanks
#11
Your resistors will also have tolerances, be sure to pick the right resistor tolerance for your project. If it calls for a high precision resistor use one.
It's a fine line between clever and stupid.
#14
Quote by call1800ksmyazz


that depends, if you are building it on veroboard that first one is fine


and yeah, use the LM741 is you're building a Distortion+, the effect was designed around that opamp because that was all that was available in the 70s (the actual thing has fallen slightly behind the times today, you can basically use any single opamp in there, try a TL071 or something....)
put a socket in there if you ever feel like experementing
#16
will a different OP-amp change the sound because i read that this one has a nice rock distortion, and also can someone give some info on my cap question please?
#18
the DOD Overdrive 250 (and probably the Yngwie Malmsteen overdrive), MXR Distortion +, MXR Microamp and Ross Distortion are virtually the same circuit except for a couple of part differences. You can build all of them with the same PCB.
The different opamps will change the sound but the regular LM741 probably sounds best in there.


as for capacitors:
the unit for capacitance is a farad, however thats a lot so smaller units are used

for larger capacitors you have it listed in uF (microfarads), that u is supposed to be the greek letter mu (μ for micro but its not practical for general use in computers.
smaller units than that are nF (nanofarads) and pF (picofarads)

1000 pF = 1nF
1000nF = 1uF

typically in a circuit like that everything is listed in uF unless it has another character by the number


in http://aronnelson.com/gallery/album19/mxr_dist_plus?full=1 i see:
2 - 0.001uF (or 1nF)
1 - 0.01uF (or 10nF)
1 - 0.047uF (or 47nF)
1 - 10pF
2 - 1uF electrolytic (because of that + sign next to it but you can use a regular non-polarized...but electrolytic capacitors are much smaller for larger values)

edit: I see now that the polarized cap on the right is listed there as a tantalum, you can use a regular electroltic in its place if you want to, there may be an audible difference but it won't be huge...
Last edited by seljer at Jul 4, 2006,
#19
thats very very very helpful

thank you soo much.

If i cant find that OP-Amp any other suggestions to keep a nice raw rock sound?
#20
Quote by thesumoftwo
thats very very very helpful

thank you soo much.

If i cant find that OP-Amp any other suggestions to keep a nice raw rock sound?


any 741 type (they might come under different names but this is the one that'll probably work best in there) or TL071 or TL061 or TL081
#22
Quote by thesumoftwo
i presume all caps are electrolytic?


nope, only the larger ones (values above 1uF most of the time). You can make any capacitor with a large enough value but it tends to become too big, but at the expense of being polarized (you have to put them in the right way otherwise bad things may happen to them) electrolytic capacitors manage to be rather small (but then there are other things like the voltages its rated for, as 1uF rated for 1200V is going to be a lot bigger than 100uF rated for 16V).
But since in effect pedals you're running things off a 9V battery the voltage rating isn't usually a problem

For capacitors under 1uF (the nF range) you've got a variety of film/foil/polyester/mylar/whatever capacitors available in different formats. Most of these are non-polar.

For capacitors of only a couple of hundred picofarads you've got ceramic capacitors any silver mica capacitors (these are better for audiophiley applications because they don't distort like ceramic capacitors).
You can get ceramics in larger values (a couple of nanofarads) but go for the film/foil type instead if you can.
#25
Quote by thesumoftwo
nah, the MXR distortion + but pretty similar apparently


if you want to see how different they are:

http://www.generalguitargadgets.com/diagrams/dist_plus_sc.gif
http://www.generalguitargadgets.com/diagrams/dist_250_sc.gif (has got a smaller value potentiometer for gain = less gain)
http://www.generalguitargadgets.com/diagrams/microamp_sc.gif (has the diodes taken out for no clipping so its just a boost)
and a different schematic but the Ross Distortion is almost the same thing too http://www.home-wrecker.com/ross_distortion_black.png
#27
just incase anyone is interested, ive decided to order in bulk form ebay, that way i can afford to make a couple of mistakes if i really do screw up and also it will work out cheaper in the long run for other projects.
#28
I just ordered 2 packs of 300 resistors from http://www.futurlec.com/ValuePacks.shtml and its got all of the common values unless you're building something that has wierder values. (the packs of capacitors are also pretty good). Many electronic sites have such packages available.
#29
wow, so would a pack like that have all the values that ill need? If so, do you know of any UK sites that would do a pack like that? same for caps.