Bixonic - Expandora  [traced]

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Re: Bixonic - Expandora

Postby devastator » 28 Feb 2009, 21:20

Hi,

Someone in French forum did one with the schematic from Geofx. Acording to him no need to the Sharp opto, used only when the switches is unconnected for the "clean" setting or low drive.

I would like to do one , espcially for the "Rythmeen" tone. Maybe in keeping just the circuit with LM308 will works (actually it's just a Proco rat) :hmmm:
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Re: Bixonic - Expandora

Postby soulsonic » 02 Mar 2009, 08:15

I will try building one without the Sharp opto and compare it to my original.
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Re: Bixonic - Expandora

Postby culturejam » 16 Jul 2009, 01:25

Soulsonic:

Any update on this? Were you able to find a suitable sub for the obscure Sharp opto unit?

Thanks!
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Re: Bixonic - Expandora

Postby Kilby » 21 Oct 2009, 15:51

culturejam wrote:Soulsonic:

Any update on this? Were you able to find a suitable sub for the obscure Sharp opto unit?

Thanks!


Smallbear have the unit in stock (apparently).

I don't suppose anybody has some PCB artwork about for this beastie as I have wanted one for ages, but they are really stupid money in the UK (and cant find any decently priced used ones).

Rob...
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Re: Bixonic - Expandora

Postby mictester » 22 Oct 2009, 00:49

soulsonic wrote:Anyone ever find one of those Sharp optos? It's an optocoupler that uses a JFET. I found the datasheet, but so far I haven't found any substitutes with the same resistance range. :?

:idea:
I wonder what the new Expandoras use? :?:


I've built Expandora-alikes using the H11F3 opto-FET. I've also used the same device in a pseudo-vibe with great success.

The only thing to remember with the H11F3 is to keep the audio below (roughly) 300 mV, because anything higher will "sneak through"!
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Re: Bixonic - Expandora

Postby Brink » 30 Oct 2009, 03:01

Kilby wrote:Smallbear have the unit in stock (apparently).

I don't suppose anybody has some PCB artwork about for this beastie as I have wanted one for ages, but they are really stupid money in the UK (and cant find any decently priced used ones).

Rob...

http://www.aronnelson.com/gallery/main.php/v/layouts-as-yet-unverified/Bixonix_Expandora.gif.html?g2_imageViewsIndex=1 maybe? It's unverified and somewhat large. And has components in weird places.
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Re: Bixonic - Expandora

Postby Brink » 30 Oct 2009, 03:31

http://www.geofex.com/FX_images/expandor.gif shows a "2206", but the 2n2206 isn't available anymore. PN2369a looks to be a sub, but could anyone recommend a more common transistor?
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Re: Bixonic - Expandora

Postby Brink » 31 Oct 2009, 01:27

I made up a doublesided B sized (2.1" wide, offboard pots, switches, LED) layout in Sprint-Layout, but haven't totally checked it yet. If there's anyone who:
1) etches doublesided boards
2) uses Sprint-Layout
3) wants to verify an Expandora layout.
then let me know and I'll get you the .LAY file.
(I'm guessing that there aren't very many people who do 1 and 2.)
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Re: Bixonic - Expandora

Postby wgtp » 14 Dec 2009, 17:39

The distorition section of the Expandora is pretty much a Rat with an op amp at the end instead of the Jfet buffer. The expansion part of the circuit is added to the feedback loop of the Ratish distortion to give the "attack" an extra boost. Many Rat mods will work here, but the opto part is the problem with cloning this pedal. Some folks claim the expansion circuit doesn't do that much anyway. Use a heavier pick? I've always been interested in it, but not sure if it is worth the extra trouble... ;)
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Re: Bixonic - Expandora

Postby culturejam » 14 Dec 2009, 18:32

Kilby wrote:Smallbear have the unit in stock (apparently).

I recently ordered the Sharp unit. It's SMD, however. :|
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Re: Bixonic - Expandora

Postby Dirk_Hendrik » 14 Dec 2009, 19:13

culturejam wrote:
Kilby wrote:Smallbear have the unit in stock (apparently).

I recently ordered the Sharp unit. It's SMD, however. :|

Why the :| ?
You just got yourself a challenge for the x-mas season! :mrgreen:
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
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Re: Bixonic - Expandora

Postby Brink » 14 Dec 2009, 19:29

I made this board a while back but haven't tested it.
You get to figure out which side to mirror to get the PNP correct. And where the pots connections go.
Green is originally top, not that that matters.
The size is 2.1" wide x 1.8" high.
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Re: Bixonic - Expandora

Postby Kilby » 15 Dec 2009, 10:05

culturejam wrote:
Kilby wrote:Smallbear have the unit in stock (apparently).

I recently ordered the Sharp unit. It's SMD, however. :|


My one knob tone Bender on vero ended up with SMD parts in it (didn't read my order sheet properly)
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Re: Bixonic - Expandora

Postby culturejam » 15 Dec 2009, 15:39

Kilby wrote:
culturejam wrote:
Kilby wrote:Smallbear have the unit in stock (apparently).

I recently ordered the Sharp unit. It's SMD, however. :|


My one knob tone Bender on vero ended up with SMD parts in it (didn't read my order sheet properly)

Smallbear only stocks one type of Sharp opto unit for the Expandora, and it's SMD. They just don't say it in the product description.
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Re: Bixonic - Expandora

Postby Kilby » 15 Dec 2009, 16:00

Damn it's just gotten to the stage that between the dual layer PCB and that SMD business I think I may just buy an Expandora and have done with it :(

BTW I wasn't implying you didn't read the spec sheet, just pointing out that I have insect legged cap on my TB
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Re: Bixonic - Expandora

Postby culturejam » 15 Dec 2009, 17:40

Kilby wrote:BTW I wasn't implying you didn't read the spec sheet, just pointing out that I have insect legged cap on my TB

It's cool.

I'm just jealous that you were able to pull it off. :)
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Re: Bixonic - Expandora

Postby mictester » 15 Dec 2009, 17:44

Brink wrote:http://www.geofex.com/FX_images/expandor.gif shows a "2206", but the 2n2206 isn't available anymore. PN2369a looks to be a sub, but could anyone recommend a more common transistor?


2N3703 works fine there!
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Re: Bixonic - Expandora

Postby wgtp » 15 Dec 2009, 21:24

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Re: Bixonic - Expandora

Postby choudy » 06 Feb 2010, 11:39

Has anybody bulit Expandora clone yet?
I've made single sided PCB for Sharp PC419 version by RG Keen schematics http://www.geofex.com/FX_images/expandor.gif, but I think there is probably some issues in expander circuit.
Signal path is OK but expnander doesn't expanding.
I've used PNP BC560 as LED driver.
Do you have some further info about it.
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Re: Bixonic - Expandora

Postby soggybag » 06 Feb 2010, 19:29

Seems like you could replace the 560 and 1k1 resistors in the second LM308 with a pot. Looks like these set the amount of compression.

Seems like you could make something similar to this using easily obtainable parts. Maybe an op-amp could be used to drive the LED/LDR. That way you could use a wider variety of parts for these.

The Flat Line compressor could be a good place to start. I wonder if you could just tack another op-amp stage on the end of a Flatline. Heck looks like you could just add a few diodes for a Rat/Distortion Plus type clipping stage.
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