Original DOD 250 Grey Spec layout,and layouts with mods and transfer images

[Brymus]

Hi I took a little time this evening and whipped up a few layouts and rendered the PNP transfers for the DOD 250 Gray Spec.

I felt bad for my part in the whole earlier fiasco,and did this as my apology to the forum.
Please feel free to use these for all personal use,and John Lyons (and anyone else) has my permission to etch these for anyone if need be.
I know this is a super simple and easy pedal ,and anyone who has made a couple of pedals could whip this up with mods in no time.
I felt like the newbies who are after the DOD 250 or the YJM pedal might find it helpful to get started with.
I really liked the board mounted pots of the last layout that was up for discusion (but the entire thread was deleted in part due to my involvement)
So now anyone who had previously wanted to build the "other" version ,but didnt want to try making their own transfer from what was posted can now build the original version I am posting.
I also did one with much improved filtering of the V+ and Vref ,with an asymetric clipping option.
And then again with dual clipping options,asymetric option, and 3 different EQ(rolloff) selections available along with the above mentioned much improved filtering.
Sorry to say that when I saved the last version DIYLC file it overwrote the simple MOD version ,so I only have two DIYLC files to let you use and tweak further but feel free to use them as starting poins I will upload those too.
They are made to use standard 24 mm pots just solder some clipped leads into the pads and the pots will support the PCB no standoffs needed.
I did notice the input and output pads are on the wrong sides of the PCB from where they go,sorry about that I didnt notice until I was done making them.I dont think its that big a deal though for this pedal.
I did double check though and the spacing for the pots is the same as the "other" layout that was taken down,so it will fit a 1590 B enclosure with the pots side by side,but the total PCB size is smaller ,if any one needs help figuring out the switches or pot mounting just post here and I will help out.
Bryan








The DIYLC files are in my layouts gallery if they are of any use to anyone feel free to download them.
http://www.aronnelson.com/gallery/main.php/v/Brymus/layouts/
You will have to click on them twice as the thumbnails didnt come out for some reason.
Bryan
EDIT fixed a couple broken words,w ords

[Brymus]

I just noticed the polarity protection diode (D1 in the bottom two layouts)  is labeled 1N4007 it should be 1N4001,sorry about that...

[Renegadrian]

Bryan, see that the Steve's topic hasn't been deleted, but only moved in the members area. It's locked, so no new posts allowed, but all the precious info about the pedal are still there. Still I remain in my position, but again I have nothing against Steve and thank him for his research, as his last post of the topic in reply to my question sums it up.

As for the protection diode, the 1n400x are the same, only differing in the max voltage they can handle, so the 4007 can handle high voltage, but it can be obviously used with a 9V. I use whatever I find around (and recycle some from old equipment)

I am glad there is interest in the 250 and 308 - I was playing with my 308 yesterday and still find GREAT - Yngwie, yeah, but I find it good in a more generic hard rock situation (and played some Dokken, Motley, Cinderella tunes...) - So the more info on these pedals the better. I am also proud to have vero layouts in my gallery. Hope you don't mind I put one here too...

[Brymus]

Not at all Renegadrian
I think the more the better,
I didnt bother to look for that other thread, glad its still available for people to reference for info on the 250.
He did post alot of useful info on the versions of the DOD 250 through the years 
I even credited Steve in my layouts since I used his idea of adding the pots to use as stand offs like the original 250s
Thanks for posting your vero layout,that will be even more help for others that like vero better.
Bryan

[served]

Hi.

So I will start building it soon. So thank you.

And I did make some changes to the board.
I am planning to build your last version. So, As I dont like to wait, I always make etchants work easy er. So I did with your layout. Its not pretty, but more efficient.
I uploaded PDF file, its ready to transfer. Just print ant your are done. You can feel free to donwload it, I will try to find a better place for it, but for now its on this addres. ( you will have to wait a sec to see the pdf.

http://web.zone.ee/served/foorum/DOD250PCB.pdf

Good luck!

[Brymus]

Hey served that looks sweet !
I was going to do that to the transfers ,as I usually do the same thing when using others from the net to save on etchant.
Plus having the ground plane larger helps with sheilding and reducing unwanted noise.
So yeah no problem and thanks for posting it for others to use.
I will probably do that to the other two transfers if no one else does first.
I still have 3 other pedals I want to draw up and post for the forum to share,so its just a matter of getting around to it,ya know.

There are a ton of DOD 250 layouts in the gallery already,but none I know of with the board mounted pots.
I just wanted to make sure anyone who wanted to use the version with board mounted pots had one that was free to use.
Bryan

[zombiwoof]

I have a question you OD 250 guys might answer.  I have the YJM 308, and I notice something, when the gain is pushed past about the 2 O'clock position the tone starts to change quite a bit.  Is this something the original 250 did, or is it a "problem" with the reissue pedal?.

I'm planning on doing the mods to change it to gray specs, but using the 1458 chip (so it won't be 100% there).

Al

[Steve Mavronis]

Hi Brymus, thanks for starting this thread about various 250 layouts. Thanks for the crediting too "if" I'm the first to use PCB mounted pots on a clone PCB layout, but the real credit there goes DOD which used them on the actual 250 and YJM308 pedals that I studied. I just figured it was a neat way to suspend the PCB without any added fasteners inside the box so why not?

If you'd like I can post the layout transfer that I made for my as-built late 70's gray 250 clone - that you helped assist me in verifying it works. Aron still hasn't created an upload area for me in the Gallery under my name but I can temporaily link them from my Comcast webspace until I code a webpage dedicated to the 250 legacy and about cloning one. I still really want to post them in his gallery because it is a nice comprehensive one stop shop for 100's of different layouts to build from.

What graphic formats are you using so things print out actual size? JPG preview image and PDF scaled at 300dpi? I'll can post both the layout artwork with the component values listed as a build guide and the trace only pattern too for etching.

I don't know if people would like off board wiring info too but the way I did mine was as a template for all my future builds using a single 3PDT footswitch.

[Joe Hart]

I have a question you OD 250 guys might answer.  I have the YJM 308, and I notice something, when the gain is pushed past about the 2 O'clock position the tone starts to change quite a bit.  Is this something the original 250 did, or is it a "problem" with the reissue pedal?.

I'm planning on doing the mods to change it to gray specs, but using the 1458 chip (so it won't be 100% there).

Al

The tone does change. The resistance and the cap create a "tone control" to ground. It's normal.
-Joe Hart

[Brymus]

@ Steve
I have a large collection of 250 and 250 based layouts as I was intending to build one before you started your threads on it.
And as far as I can tell yours is the first to use board mounted pots,aside from that you did do alot of research into the small differences throughout the years ,and I used your pot spacing,so your quite welcome for the deserved credit.
I felt the whole forum deserved credit too,due to the mods and filtering which I learned through reading threads here and there in this forum.

You and anyone else is most welcome to post any layout,artwork,image,shematic ,photo,ect relative to the 250 pedals that you wish to offer to the forum for use.
I would like to have as many different layouts,options,ideas as possible for people to choose from when building this pedal.
A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM and Zak Wylde varients as well.

EDIT I forgot to answer your question about scaling>
When printing layouts made in DYLC I just scale the image until the IC and cap pin spacing is correct.
It usually takes about 3-4 trys to get it just right,then I tape my glossy magazine paper over the one that is correct and print it again for etching.

[Steve Mavronis]

A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM and Zak Wylde varients as well.

Cool, besides the grays I was also researching some about the fist 80's yellow 250's and the reissue yellow/YJM308 too. Tell me about that Zak Wylde variant. It was based on the 250 as well? I didn't know that. Also just a quick mention of the MXR Distortion+ deserves mention as the basis for DOD's 250 overdrive circuit. They are almost identical except for component values! The 250 is basically a modified "clone" of it! The Ross Distortion pedal is very similar too so I guess it was common for companies to immitate what each other were doing.

[Brymus]

My bad, actually the Zak Wylde is closer to a Tube Screamer than a 250  

EDIT> But yeah anything that is similiar could go in this thread,sometimes I find it helpful to see how a circuit evolves as it is copied from manufacturer to manufacturer,and how it is revised to keep marketing it as new or improved or whatever.
Alot of times revisions are due to parts availabilty other times,just to save money or keep up with the competition.

[Renegadrian]

I don't know if people would like off board wiring info too but the way I did mine was as a template for all my future builds using a single 3PDT footswitch.

Personally I like schematics without the wiring, so they are easier to follow - everyone should learn on the separate wiring tutorials, images, and so on and then use them as they like. It wouldn't be helpful to see a 3pdt wiring when I'm using millenium 2 with dpdt...I'd rather see clearly where the input and output are. That's me...

[Renegadrian]

You and anyone else is most welcome to post any layout,artwork,image,shematic ,photo,ect relative to the 250 pedals that you wish to offer to the forum for use.
I would like to have as many different layouts,options,ideas as possible for people to choose from when building this pedal.
A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM.

I noticed that I didn't put this layout in my gallery, my bad...Verified by myself! What a pedal!!!

[Steve Mavronis]

Okay well here is the PCB layout Rev.8 from my late 70's gray 250 clone (circa 1979 version) that is a working pedal that I renamed as my Neo-Classic 741 Overdrive. Brymus built a prior development version of it for verification and this one is no different except for some very minor touch-ups to the trace pattern. I built two great sounding complete pedals from it in May 2010. What amazes me the most is I wasn't expecting for it to sound good on the 15 watt solid state (new Marshall MG4 series) amp that I use for practicing. You won't believe this but on the amp's clean channel my pedal makes me sound just like I'm playing through a tube amp! I'm not kidding. Quite a pleasant surprise indeed

Print at 300dpi for actual size. I've included a scale PDF version too (just make sure scaling is set to None) and the outer rectangle is just the default ExpressPCB board size so ignore that. The pad holes are not actual size to fit parts. Instead they act like a centerpunch dent for the bit to fall into when drilling the actual sized holes. The PCB size should be approximately 2.0" wide by 1.7" high and will fit within a 1590B sized enclosure.

Here is a 300dpi image of my PCB transfer pattern, and the PDF version is here: http://home.comcast.net/~snmavronis/nc741od8pcb.pdf
Note - I print to transparencies for UV transfer exposure so mirror flip this for the solder side view (so the text reads normally) if doing PnP which I assume is how it's done:


Here is a parts location graphic of the same thing shown from the component side view:


The full schematic (the PCB circuit is within the 4 circled pad markers) for a pedal wiring guide is here: http://home.comcast.net/~snmavronis/neoclassic741sch9.jpg

You notice that's version 9 because I'm working on a new PCB trace re-route Rev.9 to bring the 741 op amp output cap connection to the diode section 100% true to the original gray 250 interconnections of parts to each other.

[Brymus]

nice Steve and Adriano
It looks like the only difference between the YJM and the 250 is the taming or anti oscillation cap in the FBL of the 741.
The only difference between the the MXR distortion +  and the DOD 250 seem to be minor value changes.

Adriano which pin does the gain lug 1 go to on your YJM vero layout ?

And I should have includued a 10n to ground at the input of the super modded 250 I posted to cut down on hiss introduced at the input.
And I should have added the option of having the small value cap in the FBL of the 741 too.
There should be room to add those by just drilling some extra holes in the existing layout,
But looking at it again I also see where I could have made the layout even better and more compact.
I may do another smaller version to use 16 mm pots,and the other added mods later on.

[Renegadrian]

Adriano which pin does the gain lug 1 go to on your YJM vero layout ?

Gain lug 1 goes to ground.

[Steve Mavronis]

I believe the YJM308 uses a different input cap value (0.001uF vs 0.01uF) than the gray 250 as well, besides of course the different op amp too. I have a YJM308 layout that I drew from looking at the real thing with ExpressPCB when I was thinking about modding that pedal:

I was first learning how to use ExpressPCB when I made this. Sorry it's kind of crappy and I should redo it:


With mod instructions from another forum. Personally I'd ignore step 2 and keep that cap to stay in gray specs:

[Renegadrian]

yeah, I built a 250 with an input cap switch (1n-10n) and it's a difference. Obviously the IC is different. (a dual op-amp hald used...)

[zombiwoof]

nice Steve and Adriano
It looks like the only difference between the YJM and the 250 is the taming or anti oscillation cap in the FBL of the 741.
The only difference between the the MXR distortion +  and the DOD 250 seem to be minor value changes.

Adriano which pin does the gain lug 1 go to on your YJM vero layout ?

And I should have includued a 10n to ground at the input of the super modded 250 I posted to cut down on hiss introduced at the input.
And I should have added the option of having the small value cap in the FBL of the 741 too.
There should be room to add those by just drilling some extra holes in the existing layout,
But looking at it again I also see where I could have made the layout even better and more compact.
I may do another smaller version to use 16 mm pots,and the other added mods later on.

AnalogMan says the extra 25pf cap is used in the 308 because they used a 4558 in the pedal (actually only half of the dual 4558 IC), which has a wider frequency range than the original 741 IC.  The added cap attempts to make the 4558 sound more like the 741 circuit, and isn't needed if you are using a 741 in there.  One of his mods uses a 1458 instead of the 4558, which according to him is actually a dual version of the 741 chip, and sounds more like it in the circuit (and also doesn't need the 25pf cap).  He says the 308 does sound a little noisier with the 1458 in place of the 4558, but closer in sound to the 741.

Maybe you are already aware of this, but you mentioned having the option of using the 25pf cap with the 741, which shouldn't be necessary.

Al