Tycobrahe - Parapedal  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
spookybonus
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Post by spookybonus »

yeah i would love to get the RG files as well if anyone has them saved.

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Post by spookybonus »

i made up a parapedal from the schematic, but i used two 22uf caps because i didnt have any 33uf caps on hand...do you think that might be why the effect seems to not quite sound as "full" as the demos i have heard online?
i wish i would have bread boarded this before i made it on a pcb, to would have been much easier to swap the parts in and out. :slap:
i have a bunch of 47 uf caps i could try out, if that would increase the effect.

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phibes
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Post by phibes »

47uF will be a-ok!
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Dan N
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Post by Dan N »

spookybonus wrote:yeah i would love to get the RG files as well if anyone has them saved.

They're still on his site. Go to http://www.geofex.com/ and scroll down to 8/25/06 and you'll find:

http://www.geofex.com/FX_images/parapedal.gif
and
http://www.geofex.com/FX_images/newparapedal.pdf
Dick joke has expired.

giannyx
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Post by giannyx »

Sorry guys, is there a components list anywere?

There are no informatio about U1 and U2...

Also no information about the Pots.

Is there anybody knows it?

Thanks a lot!

:horsey:

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Dirk_Hendrik
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Post by Dirk_Hendrik »

giannyx wrote:Sorry guys, is there a components list anywere?

There are no informatio about U1 and U2...

Also no information about the Pots.

Is there anybody knows it?

Thanks a lot!

:horsey:
The pots say 10k.
The opamps are standard pinout dual opamps. This means that if you put in a standard dual (TL072, 4558, LM833, 1458, NE5532, etc etc) opamp.... it's going to work!
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

giannyx
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Post by giannyx »

Thanks a lot Dirk!

Both pots are 10K?

I'm trying to find the second one! :hmmm:

:oops:

:D

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phibes
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Post by phibes »

There's only one pot. It's a dual-gang.
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Post by giannyx »

phibes wrote:There's only one pot. It's a dual-gang.

:oops: :oops: :oops:

Right! Sorry.

But C3 hasn't a value...what value do you suggest to use?

Thanks a lot!

:D

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phibes
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Post by phibes »

It was .001uF on the original schematic. I think that value was verified.
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Post by cortezthekiller »

As an update I've built the parapedal from the layout/schematic available here and can say that this pedal needs an AUDIO taper for the dual pot. Otherwise the sweep is way too bunched up at the toe end of the range. Other than that it works perfectly. Just keep in mind that the Hot connections mentioned on the layout are the counter clockwise connections on the pot (usually pin one). This confused me somewhat though it specifies on the schematic.

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Nocentelli
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Post by Nocentelli »

I'm going to have a go at this, but i'd like to use an expression pedal to control the sweep. It seems like a fair bit of exrtra circuitry, but I'm going to have a go at using the tonegod's "Rock N'Control" (three pole - fig 5) circuit, but doubled-up to replicate the dualgang pot: Image

My main concern is tuning the six trimmers required for a dual circuit whilst trying to measure the reciprocal increasing and decreasing resistance across two ganged simulated potentiometers. Sounds like a painful process.

Can anyone suggest an simpler method (of using a single expression pot to control a simulated dualgang pot)? I'm going to get it working hopefully with a dual 100k pot (I've read elsewhere the value of the pot isn't necessarily critical), and one other idea i had was just to use a fixed resistor for the "lower half" of each gang of the pot, and use two single LDRs for the top halves. I could then just use the passive two pole version.
Steven_M wrote: 21 Jan 2011, 17:52
biffa wrote: Sorry,but u r not the only member here

I'm not? Well fuck this site then. I only want meaningful conversations with myself.

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Nocentelli
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Post by Nocentelli »

link to tonegod's circuit didn't work, try this:

http://tech.thetonegod.com/rockncontrol/rock.html
Steven_M wrote: 21 Jan 2011, 17:52
biffa wrote: Sorry,but u r not the only member here

I'm not? Well fuck this site then. I only want meaningful conversations with myself.

kymar
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Post by kymar »

corrected schematics
corrected schematics
pcb.jpg
pcb.jpg (69.36 KiB) Viewed 1208 times
layout
layout
Parapedal lay.jpg (99.12 KiB) Viewed 1208 times

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Fender3D
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Post by Fender3D »

kymar wrote:corrected schematics
Why D2?

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Post by kymar »

Parapedal-8_zpsea0bf284.jpg

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Fender3D
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Post by Fender3D »

oh ok,
I did guess it was your layout...

...then D2 shouldn't be 1N4001, rather a zener...
check its name, please.

Thanks

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Post by kymar »

Fender3D wrote: ...then D2 shouldn't be 1N4001, rather a zener...
check its name, please.
My fault, of course zener, otherwise opamp can`t operate.
It is 1N5231 instead of 1N4001, marked D2 on schema, please correct it.

fatboy757
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Post by fatboy757 »

Im terribly new to this but can anyone make a veroboard or tag board layout with the values listed. I dont know how to do that. I understand symbols in schematics and values but dont have a full grasp on everything.

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Post by JimSalabim »

Hi! Maybe some can help:

I would like to build a Parapedal clone in a Dunlop style Wah enclosure and use the schematics and layout from geofx.com:
http://www.geofex.com/FX_images/parapedal.gif
http://www.geofex.com/FX_images/newparapedal.pdf

I would like to use the third layout of the PDF (the smallest one) and I have a few little questions (I am new to all that stuff):
  • The parts I need are the ones listed in the gif-file with the schematics?
  • There is no value for the C3 capacitor. Someone wrote it has to be a 1nF capacitor. Is that correct?
  • Do I use two TL072 opamps for U1 and U2?
  • Which diode do I have to use for D1? I read something about a Germanium diode: 1N270. Is this the right one? Or do I use a silicon rectifier diode 1N4001? Or something else? :-)
  • What does J1, J2 and J3 in the layout mean?
  • Which dual pot would you recommend? Does it need a long shaft to fit in a Dunlop style enclosure?
  • Can I use the normal Dunlop wah switch to turn the pedal on? How do I wire it?
And if I decide to use the second layout of the PDF, are the values the same? Which values are R14 and R15 and which diode is D2?

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