Seeking schematic wisdom.. attempting first pedal build (Ts-808 clone)

Started by CasterPaul, August 29, 2010, 06:37:57 PM

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CasterPaul

Hello all-knowing enlightened ones (aka butter-up attempt!)
I'm a.. you guessed it... newbster, and am interested in the world of effects, more specifically to be used as a part of my arsenal in the conquest of the guitar. That said, one might have already assumed that this battle can be fought more efficiently, if the warrior could only custom design his weapon to effect the result that he/she is looking for at a given time for a given task. I am ignorant as of now, but thanks to the help of this web-site and people like you, I'm not as ignorant as I was yesterday, and only plan on becoming more wise in this area. This is the schematic i want to tackle   http://www.schematicx.com/view-schematic/ibanez-ts808-tube-screamer-overdrive-pro-schematic/

The hardest thing for me is understanding the switch from the schematic.. am I reading this right?.....
-the pedal in the diagram is off,
-I would connect the points the arrows (poles) are pivoting on at sw1a-c to the three center lugs of my 3pdt switch,
-the top three lugs would connect to the points where the arrows are touching,
-the bottom three to the three points remaining ( in respect to their location)
-All the Vr , V+, and grounds ofcourse are common with the others like them right
-where the schematic shows lines to the poles on the switch leading from other poles, i have to connect jumpers where they are not closed?
Is it common for schematics to omit numbers in their part lists (i.e. no R4, C6,D3) and D5 doesnt specify which kind of diode, what should I use?

Thanks for your investment into me and others.... blessings


ianmgull

You are correct about Vr, V+, and Ground. They are common.

Sometimes various parts are left out of the numbering scheme for whatever reason (you're not crazy)

Just about any silicon diode will work for D5; it's purpose is only reverse polarity protection.  (a 1n914 will work fine).

As for switching there are a number of diagrams for wiring your 3PDT. GGG (the site that schem is origionally from ;) ) has many options:

http://generalguitargadgets.com/tech-pages/51-switching-and-wiring/33-many-bypass-switching-options


smallbearelec

Hi--

People who build Stompboxes often wind up looking for parts on my Stock List, so I want them to have good first experiences.  IMO, the learning curve for what you are trying to do--learn to read a fairly complex schematic and then build a pedal from that--may leave you frustrated, and I would lose a potential customer.  A couple of suggestions:

--Were you planning to do a soldered build directly from the schematic?  This is almost certain to give you problems. As you have clearly noticed, there is stuff that even a well-drawn schematic assumes that you would know that you might not.  I strongly suggest doing your first build--whatever it is--on a solderless breadboard.  More on this in a minute.

--You should not be concerned with the bypass switching or power switching at this point.  What you want to do is get a circuit--even a simple one--working on the breadboard from input to output. Once you have done that and heard the result, you can add the switching that makes a finished pedal.

Here are a couple of tutorials that might help.

http://www.smallbearelec.com/HowTos/Breadboarding/BreadboardIntro.htm
http://www.smallbearelec.com/HowTos/BreadboardICDist/ICDist.htm

The first one explains the basic use of a solderless breadboard, and the second describes a distortion that is not too dissimilar from a tube screamer. The unswitched audio and power are the way I suggest that beginners start. Between these articles, you might be able to suss out enough to breadboard the TS if you choose to. My suggestion would be breadboarding something simpler, maybe an MXR Distortion Plus, but it depends on how much you want to bite off.

Happy construction!

jasperoosthoek

A very good resource is this site: http://www.tonepad.com/getFileInfo.asp?id=81 You can take some perfboard and directly use the Tonepad layout. The holes in the perfboard are aligned to the PCB layout you find there.

This is how I made a lot of my effects ;D
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CasterPaul

thanks all! Very helpful resources... I feel much more equipped to start experimenting now. One more question, I have never been able to find a 1uf low voltage (50v or less, not even 100v actually) cap locally.. a BP one at least.  What's the significance of using the BP as oppesed to a polarized electrolytic or tant? COuld I sub one of those? Thanks for saving me future headaches!

CynicalMan

Polarized electrolytics work when the voltage on one leg of the capacitor will always be more positive than the other. Bipolar electrolytics are used when that doesn't happen, because they can work without one leg always being more positive than the other. They can be made by taking two electrolytics of twice the value you want and putting them in series with either the two positive legs connected or the two negative legs connected.

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CasterPaul

awesome! Are there any negative tonal implications as a result of using two series electros instead of metal film?

CynicalMan

I assume you mean poly film. Some would argue there is, but I'm sure you wouldn't hear it.

jasperoosthoek

I used non-electrolythic bipolars, ceramic or film dunno (???). I think these used because they were available at the time for little money. I don't see any reason why it should be different for audio frequencies. If you want to be sure use what IronicalMan suggested ;D
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smallbearelec

Quote from: CasterPaul on August 30, 2010, 11:10:52 AM
I have never been able to find a 1uf low voltage (50v or less, not even 100v actually) cap locally.. a BP one at least.  What's the significance of using the BP as oppesed to a polarized electrolytic or tant?

When pedal manufacturers use tantalum, it is to get as much capacitance as possible into the least space. But the audio quality is not as good as poly film or aluminum electrolytic. As a rule, I will use low-voltage box-style or radial poly films (my SKU 1106 or 1107) where 1 mf. is wanted, because there is no issue with polarity, transparency is fine and they are no larger physically at that value than electrolytics. Above 1 mf., I start using radial aluminum (my SKU 1404 and following).


jasperoosthoek

Didn't know those existed. :) I should have searched your site even more thoroughly. Thanks Steve!
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