Catalinbread - SCOD (Super Charged Overdrive)  [traced]

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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby caspercody » 10 May 2011, 00:02

Never mind on my submitted schematic, in previous post.
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby caspercody » 10 May 2011, 16:49

Okay, I was able to delete my attachment. But looking at the photos and the schematic (by Madbean) it does look correct. I see in the photos a blue wire that is not shown on the schematic, or shown in the drawn up photos. Is this wire for the LED? It connects to the 1K resistor. The photos do show a wire between the 2nd and 3rd terminals on the 50K contour pot, but this is not shown on the schematic?
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Re: Catalinbread - SCOD (Super Charged Overdrive)  [traced]

Postby rcustoms » 11 May 2011, 06:04

MAYBE AN OPTIONNAL PCB :lol:
SUPER CHARGER.pdf
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby rcustoms » 03 Oct 2011, 18:57

i made that pcb work by herman request and he toll me that work ok,just verified if you have any doubt
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby VooDOOM » 03 Oct 2011, 19:47

Awesome!! thanks..I will post results :) Just may take me a while to source the parts:)
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 30 Jan 2012, 11:36

Hi,

yesterday I thought I give this thing a go. I compared the several schems around here in this thread with the posted gutshots. I don't know who ever came up with the 100nF source bypass cap at q1 but as far as I can see there's no single 100nF cap used in the whole circuit (as far as I can trust the gutshots with written values)! But what it looks to me is, that's there a 100µF cap from source to gnd at q1 which makes at least to me far more sense. Furthermore (though a minor issue) the 61k resistor in the vref supply rail is in fact a 62k (which is also a more common value) as you can see clearly it has the color code "blue, red, orange, gold" written on it.
I built it up doing these small changes et voilá it works, though I'm not sure if it works like the original unit. But what we've got is a usable distortion unit with quite a lot of gain on top of the gain pot. Only the lowest setting seems a bit too weak to me compared with demos available on the net. The contour controll is my opinion quite effectiv though it doesn't work like your ordinary tone controll - its a different kind of beast. But I like it.
I attached a corrected version of madbeans schematic as it was the most readable one flying around here. Hope you don't mind, madbean.;) I case you do feel free to informe the mods to delete it. No offense none taken.

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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby mictester » 30 Jan 2012, 22:52

I used Madbean's circuit, but added a bias tweak (I didn't have a 62k resistor anyway!)

It sounds pretty good (needs a bit of tonal tweaking), but it was only after I built it that I realised its provenance - it's "Jez's Nut Cruncher" from the late '90s with a few added bits!

SCOD_Vero.png
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 30 Jan 2012, 23:10

... and don't forget jack ormans mosfet boost. But it's a cool hack und has some good sounds in it. Though my favourite ones aren't the hi gain sounds but the lowerish ones. I've noticed the similaritys to the nut cruncher too, as i already built a year ago or so. But how would you do else with a 4007?
Since many jfets aren't in production anymore we should turn our heads toward those inverter based designs. I somewhat dig these cmos designs and achieved some very good sounds with them.
So Chris, what are your tweaks?

Edit: Read only your first version of your post. So the tweak should be clear now.
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby mictester » 31 Jan 2012, 00:14

I've give the first MOSFET some treble boost (330 ohm resistor in series with a 10n cap) in parallel with the source resistor, removing the 100µ.) I increased the drain resistors (both are now 6k8) and I re-biased the gates. It's now much brighter, and with fairly low settings of the gain control, you can get really nice "chime" with a Telecaster into an AC30.

I'm going to do a nice PCB for this one, including the DPDT bistable relay bypass circuit.
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 31 Jan 2012, 00:28

Nice idea! Funnily I had something similar in my mind. I tried boosting the scod with a treble/midrange booster and did like it a lot. So my 2nd thought was about how to change the first mosfet boost into this region. So Chris, thank you for your input. Will try it if I have some spare time. :thumbsup
For your bypass idea: Since we have some inverters left from the cd4007 why not use one to make an millenium bypass? Should be easy and reduces the "waste" of gates. ;)
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby mictester » 31 Jan 2012, 09:20

HEAD wrote:=
For your bypass idea: Since we have some inverters left from the cd4007 why not use one to make an millennium bypass? Should be easy and reduces the "waste" of gates. ;)


I wouldn't risk it. There's a lot of gain going on in that IC, and you'll probably get "pops" as the current is connected to and removed from the LED - the current through the LED will be MUCH bigger than the current otherwise drawn by the IC!

The micro-current bistable relay bypass works so very well, gives click-free switching, doesn't degrade over time, only draw a few µA (so doesn't flatten your battery) - and it costs less than a good quality multi-pole footswitch. It also enables simple remote control, too. It was originally developed to use up all the SPST switches I'd removed from pedals over the years. The old ones were very robust.
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 31 Jan 2012, 09:36

Hi Chris,

I know all the pros of your solution but I have to admit that I don't like it. For my personal use the disadvantages overweigh the advantages of this. The relays itself costs about 1,50€, a good quality spdt switch costs nearly the same as a dpdt. What I would like would be controlling the relay with a momentary spst, which is possible but gives you a few more parts what I personaly don't like about that.
But let us not talk about the bypass but about the circuit itself. ;)

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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 31 Jan 2012, 17:54

Hi Chris,

another idea: A voltage sag controll in the 9V 4007 supply rail. I know some design which use that trick very successfully - I did as well. It gives you a kind of a bias controll. With the voltage turned down it gives a less stiff and warmer sound. I might try that too tonight...

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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby mictester » 31 Jan 2012, 20:45

HEAD wrote:Hi Chris,

another idea: A voltage sag controll in the 9V 4007 supply rail. I know some design which use that trick very successfully - I did as well. It gives you a kind of a bias controll. With the voltage turned down it gives a less stiff and warmer sound. I might try that too tonight...

Helge


No harm in trying it!
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Re: Catalinbread - SCOD (Super Charged Overdrive)

Postby HEAD » 01 Feb 2012, 12:11

Hi Chris,

is there anyway to keep the original gain of the first mosfet stage but turning it into a treble boost? Did try your mods but it wasn't my cup of tea. ;)

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