Colorsound - Power Boost / Overdriver

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

I've found this.
Maybe anybody have better ones?
Attachments
vox_powerboost_004.jpg
vox_powerboost_005.jpg

.Mike
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Post by .Mike »

I did another layout for the CSOD, and I forgot to share it here!

Super easy build. Board-mounted pots w/ gain control, made to fit very comfortably in a 1590BB.

Image Image

Here are the ExpressPCB pcb/sch files and PDF toner transfer: http://www.justonemorebuild.com/project ... morebuild/

Please let me know if you build one! :D

Mike
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monkeyxx
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Post by monkeyxx »

Very nice! Very creative use of circuit board and LEDs on the exterior

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Post by agoldoor »

.Mike wrote:I did another layout for the CSOD, and I forgot to share it here!

Super easy build. Board-mounted pots w/ gain control, made to fit very comfortably in a 1590BB.

Image Image

Here are the ExpressPCB pcb/sch files and PDF toner transfer: http://www.justonemorebuild.com/project ... morebuild/

Please let me know if you build one! :D

Mike

Wow Mike! Nice work! How did you manage to cut out the Overdrive part so precisely? It looks perfect, almost like it was machine-molded or something!! How did you pull that off??

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Post by .Mike »

agoldoor wrote:Wow Mike! Nice work! How did you manage to cut out the Overdrive part so precisely? It looks perfect, almost like it was machine-molded or something!! How did you pull that off??
Thanks. The top is a just piece of copper clad board, toner transferred/etched just like a circuit board. I think it looks as sharp as it does because it is high contrast. The glowing letters are surrounded by a big area of copper, so the only area that lights really bright is the text, and there is not a lot of light leakage. Also, it is strongly back-lit-- three superbright yellow LEDs @ ~7.5mA each. I don't use batteries... heh. :)

The patina effect is done with liver of sulfur, and takes about 5 minutes. It really isn't as blue as it looks-- that is my TV reflecting. You can get anything from flat black to cool colors, and it seems to be evolving over time.

Mike
My website: America's Debate | My effects site: Just one more build...

kwame
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Post by kwame »

Any notes on where to start with possible mods for this circuit?

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Post by Ben N »

Mods? I would start just by socketing different transistors. But also look at the Throback Overdrive Boost. Unfortunately, it has never been reversed here to see how they implemented the mods, but it supposedly sports less harsh distortion in germanium mode.

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Post by Bernardduur »

That germanium talk on the website; wouldn't it just be a germanium diode + germanium transistor wired as a diode to provide simple hard clipping??
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Davelectro
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Post by Davelectro »

Mods? This thing sounds really great as it is, but needs a master volume badly. That's all.

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Post by kwame »

I know they sounds great and have clone with a master volume already. I was referring to what sections of the circuit specifically for gain increase/reduction, tonestack changes (besides the input and output caps) and people's experiences with different transistors. Nothing crazy

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Post by Davelectro »

I've have found two things while playing around with this circuit in Multisim.

1) Connecting the 12K resistor as in the 18V "power boost" version results in a huge peak around 120hz.

2) A low value cap (100-470pF) between Q3's base and collector keeps high frequencies and hiss under control.

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Post by Ben N »

Bernardduur wrote:That germanium talk on the website; wouldn't it just be a germanium diode + germanium transistor wired as a diode to provide simple hard clipping??
Correct, as it turns out. Underwhelming, really, but easy enough to try. The switchable pregain control is also pretty basic, but not a bad idea. If and when I ever build this, I think it will be with a charge pump, and switchable between Overdriver and Power Drive modes.

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yeeshkul
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Post by yeeshkul »

Guys has anyone measured the collector voltages on an original 18V Power Boost?

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Post by modman »

similar.png
yeeshkul wrote:Guys has anyone measured the collector voltages on an original 18V Power Boost?
https://www.freestompboxes.org/viewtopic.php?f=10&t=17757
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Electric Warrior
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Post by Electric Warrior »

Battery: 18.84V
Q1 C 6.43V B 3.92V E 3.54V
Q2 C 11.53V B 6.44V E 5.82V
Q3 C 10.19V B 2.77V E 2.23V

Since the factory schematic calls for 5V for Q2 and Q3's collectors for the 9V versioin, I guess they were aiming for 10V in the 18V version.

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yeeshkul
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Post by yeeshkul »

Excellent, thnank you!

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Post by dgmz »

Electric Warrior wrote:Scored a Power Boost recently. Here are some photos:

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I restored it back to 18V:

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It seems like these early units came with PP4 batteries. The later ones with the PP3 clip had an additional terminal on the board where the battery clips connected with each other.

Only difference to my schematic is that it has a combination of 6.4µF, 4.7µF, 22µF and 25µF electrolytics instead of the usual 4.7µF and 22µF or 6.4 and 25µF, but no big deal.
Transistors are BC184L.
Does it sound different to copies/clones/replicas you have tried?

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Electric Warrior
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Post by Electric Warrior »

I was going to build a clone, but then I scored this old thing. :D Now I have nothing to compare it to. Sorry!

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Post by Manfred »

I made an approximate PCB clone for non-commercial purposes only.
Sorry, due to recent experiences I must mention the restricton of use.
PowerBoostLayout.JPG
PowerBoostPCBComponents.pdf
(16.1 KiB) Downloaded 81 times
PowerBoostPCBSolder.pdf
(12.11 KiB) Downloaded 80 times
PowerBoostPCBSolderMirrored.pdf
(12.13 KiB) Downloaded 62 times

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bettsaj
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Post by bettsaj »

I did this last year.... My board layout is here
powerboost_rev3_mirror.jpg

And the BOM
BOM.xls
(245.5 KiB) Downloaded 58 times
This is for the 18v Powerboost, and not the weedy 9v Overdriver.
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