Advice needed, stomp box in a pickguard.

[zurpman]

Hey guys,

I want to build a fuzz inside of a guitar that can be used with a kill switch, so you can tap to activate the fuzz, letting go kills the fuzz and returns to normal sound.

On guitar fetish I noticed they have circuits that can be wired into a pick guard and they are all around $30-60. That is where I got the idea and would rather build it myself. I did find an easy fuzz pedal to build called the bazz fuss from a youtube video, here's a link to that video, and the parts list just below it if you do not want to watch the video.

https://www.youtube.com/watch?v=Rv5iQ_aenX8

bazz fuss
           
mpsa13 transistor
10 ohm resistor
100 NF capacitor
2.2 uf capacitor.
diod 1n4148 or 1n914.

I am building a kit guitar with my brother and have two arcade buttons that are momentary buttons and should work for what I want to do. One will be for the fuzz pedal. The other is a kill switch, but I would much rather use it for circuit bending the fuzz pedal. IF I could do that with this simple pedal circuit I would use one button to activate the fuzz (while holding it) and tap the other button to circuit bend the pedal effect.

I looked for the simplest circuit I could find so I could fit it all in there with the arcade buttons.

My questions are these, Can I use a Mosfet IRF520 in place of the mpsa13 transistor? and for the 1n418 diode, can I replace that with a 1n4001? If not is there another simple build I could use with different components? And lastly would any of you be kind enough to give me a schematic of how I should wire it with the arcade buttons to get the desired effects?

Oh one other thing, the build does not mention where to place a pot, but I would need one to address volume issues, any suggestions to simplify that as well?

Thanks for any and all help you can provide.

[suryabeep]

What guitar are you using? just curious.
About the diodes: http://www.diystompboxes.com/smfforum/index.php?topic=79986.0
About the transistor:   http://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=0.31&ucb=45&uce=45&ic=0.1&tj=150&ft=100&hfe=800&caps=TO92
http://www.diystompboxes.com/smfforum/index.php?topic=32187.0
Use a 2n5088, they're insanely common.
Circuit bending this as it is may not really be possible, but I may be wrong. If you have more space inside the pickguard cavity, I'd highly recommend building in an octaver too (there's a simple one on pg 3 - http://www.diystompboxes.com/smfforum/index.php?topic=71134.40)
If you're not picky about making vero cuts, you can probably make the whole circuit pretty small, including the switches.

[smallbearelec]

have two arcade buttons that are momentary buttons and should work for what I want to do.

It's not that you can't do this. However, it may be a little more complicated than it seems.

I think maybe you don't realize that the switching has to provide bypass; it has to be able to switch the guitar either directly to the instrument's output jack or to the jack through an effect circuit. The MOD boards do this with a double-pole push-pull switch that is part of one of the pots.

http://smallbear-electronics.mybigcommerce.com/alpha-single-gang-16mm-w-dpdt-push-pull-switch/

If you prefer pushbutton switching, it would be possible to do this with a tactile switch, either latching or non-latching:

http://smallbear-electronics.mybigcommerce.com/dpdt-latching-pcb-mount/
http://smallbear-electronics.mybigcommerce.com/dpdt-momentary-pcb-mount/
http://smallbear-electronics.mybigcommerce.com/tactile-switch-caps/

You could do this on your own, but you should first be sure that you are happy with whatever fuzz you want to do it with. I have built the Bazz Fuzz and have made it work, but it's not my favorite variant of the old Electra. Buy a breadboard if you don't have one. Set up the Bazz and see if you like it, and then set up my Ursa Minor:

http://diy.smallbearelec.com/HowTos/BreadboardUrsaMinor/BreadboardUrsaMinor.htm
http://smallbear-electronics.mybigcommerce.com/breadboard-the-ursa-minor/

Once you know exactly what you want to commit to solder, you can work out the switching arrangement.

Happy Construction!

[zurpman]

 Thanks for the replies.

Suryabeep, it is just a $100 kit I purchased with a strat style body. Thanks for the links, I will consider the octaver, this is just a fun project for me. So all ideas are welcome!

Smallbearelec,
I have a vague idea of how it works, but I am a novice. I know the basics of the mod boards from guitar fetish, but not sure of the inner workings of it. I am looking to use the first switch to turn the fuzz on/off and gain a flutter effect, and the secondary button would be great if I could make it a circuit bender for the fuzz, but that does sound a little complex for the room I have available.

So the second button would be a normal kill switch. Thanks for the links you have given me as well. I will check out the ursa minor if I have the parts available to me, it looks pretty cool. I'm not extremely picky about the fuzz sound. Just looking for something that will work in the small space I have.

Can the momentary (arcade buttons) switches be set up to do the needed bypass? I can cut more wood out from under the pick guard if needed.

Thanks again for the help, it is much appreciated.

[suryabeep]

I think a normal killswitch in a guitar is just a switch that routes the guitar signal after all controls to either the output jack or to ground. Instead of the connection to ground, connect it to the in of whatever circuit you decide on. Make that an SPDT momentary push button, use a toggle for the circuit bend option.

[thermionix]

If you want true bypass (I'd assume he does) then you'll need DPDT, as Steve recommended above.

[deadastronaut]

good advice from steve as always...

+1 on getting a breadboard, try it before you actually build it. (essential tool)

or needlessly chop more wood out....

[smallbearelec]

I have a vague idea of how it works, but I am a novice. I know the basics of the mod boards from guitar fetish, but not sure of the inner workings of it.

That's why I'm explaining some practicalities.

Can the momentary (arcade buttons) switches be set up to do the needed bypass?

No. The arcade buttons I'm familiar with (from when I used to repair commercial games) were just simple contact closures...single-pole switches. Take a look at the schematic near the end of this article on building the soldered version of the Ursa Minor:

http://diy.smallbearelec.com/Projects/UrsaMinor/UrsaMinor.htm

The description there of how mechanical bypass works is general; it applies to any effect. We usually use a three-pole switch to accommodate an in-use LED, but the basic double-pole signal-switching arrangement is what you are concerned with. Study the schem and the description so that you understand what's happening. If the schem is confusing at first, stay with it. Learning to read a schem and relate the symbols and lines to physical parts is part of the learning curve.

NB: The idea of using a simple contact closure to change the effect (from clean boost to fuzz, for example,) is entirely reasonable, but get the basic idea, with in/out switching, working first.

[duck_arse]

see here for bazz details, including volume pot placement:
http://www.home-wrecker.com/bazz.html

.....
bazz fuss
           
mpsa13 transistor
10 ohm resistor
100 NF capacitor
2.2 uf capacitor.
diod 1n4148 or 1n914.
.....

you want a 10k or 100k resistor, not 10R (10 Ohm).

the bazz has been tried in a million different formats - possibly even with a mosfet.

[thermionix]

(from when I used to repair commercial games)

I did that for a brief time also.  I seem to recall those buttons were quite deep, like considerably more than an inch.  That's some serious guitar body routing.

[Mark Hammer]

I've been urging caution and good judgment when it comes to on-board effects for a long time, now.  For several reasons:

• Keeping tabs on batteries inside the guitar is a nuisance.
• Since the onboard effect/s is/are hardwired to be first, you can't do any additional toneshaping of what you feed the onboard circuit (which may or may not need such toneshaping or preparation)
• Some things are just done better, and with more flexibility OFF the guitar; you can't always put the controls where they are optimally located on the guitar
• There's only so much room for installing controls, without doing grievous damage to the guitar

In your case, as well, you want to be able to "work" the injection/insertion of the effect.  Seems to me that you'd be better off doing that with your foot than with your picking hand.  In which case, what I think you really want is a fuzz pedal with electronic switching that can be made momentary, as well as "latched".

This older Small Clone pedal shows one possibility.  A SPST stompswitch is used here to turn on a FET.  As with many modulation/delay-based pedals, the clean signal is always on and in-circuit.  All the "bypass" does is cancel the delay signal so that it isn't mixed in with the dry/clean.  Here you can see that, when the switch is closed, it allows current to flow through the LED, the 4M7, and the diode, to turn the FET "on" and change it from a very high resistance to a very low resistance.  If the switch is a momentary, you can turn the FET on for as long as you hold the switch down, and it turns off the virtual instant you remove your foot.  The .047uf cap is there to add just the teensiest bit of turn-on time.

That's half of what you want to do.  In the drawing, you can see that the clean signal passes through a 22k resistor to the "mixing node" where the dry and wet get combined.  Imagine that there was a 12k and 10 resistor instead of 22k, and that the wire going to the diode that feeds the FET went to a second diode, feeding a second FET, but that FET went from the meeting point of the 12k and 10k to ground.  When you press the stompswitch down, the one path is connected to the output, but the 2nd FET provides a low-resistance path to ground, essentially turning the volume of the clean signal pretty well off.

What I've ilustrated is not so much a "bypass" as a sort of foot-actuated signal-alternating system, that switches back and forth between two versions of a signal as fast as your little foot can do it.

Ideally, there would be some sort of input buffer that feeds a clean signal to the output as well as feeding the fuzz of your choice.  The momentary footswitch determines which signal makes itto the output stage: the clean or the fuzz.  Does that sound about right?

[zurpman]

Hey guys,

Thanks for all the replies. One thing I didn't really make clear and might help is that the whole point of doing this is for a fun project and I want to build the pickguard to look and function as much like a game controller as I can.

It really doesn't matter if the effect is a fuzz, distortion, or even a sound like Mario hitting his head on a brick. Anything is good as long as it alters the sound and fits the controller theme.

The buttons are a concern, but they don't seem too large to me, I order a red and blue button and here is a link to them.

http://www.ebay.com/itm/Sanwa-Denshi-Original-OBSF-30-Red-Push-Button-JAMMA-guitar-killswitch-30mm/171721643428?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I also ordered a dpdt switch incase the arcade buttons wouldn't work, link to those are here.
 
https://www.amazon.com/250V-120V-Momentary-Button-Switch/dp/B008ICMTXI/ref=pd_cp_263_1?_encoding=UTF8&pd_rd_i=B008ICMTXI&pd_rd_r=KNFRHT6T8HYX8Q4TGR4W&pd_rd_w=1rfVq&pd_rd_wg=Q0QXc&psc=1&refRID=KNFRHT6T8HYX8Q4TGR4W


Mark Hammer,
Thanks for the schematic and suggestion I like that as well and will build it for a different project, it's a cool idea and I can use it with something else I've got in mind.

I'm waiting on a breadboard so I can start building and experimenting with some of the ideas you have all given me. In light of what I said above about my controller theme....

Does anyone have any ideas of ... well, anything really that would be cool to try to incorporate into this guitar build?

[Eddododo]

My 2 cents on the switch... they make those switcher pots that are like... spring push (push and it pops out, push and it goes back in) that function JUST like push-pull.  2 pole 2 throw

[duck_arse]

it might not be too hard to pull the oversized guts from an arcade style pb and retrofit a small tactile or pushbutton inside/under the dome.

isn't there some fuzz circuit called the atari or the 8-bit or something? that'd fit the theme.

[zurpman]

duck_arse,

Hey man thanks for the info on that fuzz, I have no clue how to build it. I want to build everything inside the pickguard on the guitar. But, that is awesome, thanks again for pointing that out, I had no idea that pedal even existed!

[duck_arse]

if'n you search this'ere site for "atari punk", it'll throw up some resources. and modding/bending a 555 circuit - the possibilities are endless (and probably involve ldr's).

[tonight, we ride]

[zurpman]

duck_arse

Hey, thanks for the heads up on what to search for. As I said I'm a novice ... well beginner and wasn't even sure what to ask when I first started this thread. I do happen to have a few ldr's, and 555 chips on hand so this could be a good way to go for me.

Thanks.