Mega Percussive Synth

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windspirit
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Mega Percussive Synth

Post by windspirit » Fri Apr 05, 2013 6:02 pm

So I just ordered a MPS circuit board from electro-music.com and it is turning out to be a huge pain in the arse to find some of these exotic resistor values. Mouser and digikey don't even stock 3.9k resistors, much less at the wattage/ tolerance specifications required.

Has anyone else built this thing and found a good source for these obscure resistors?

I know this topic is very exciting but i could honestly use some help.

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carynrich
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Post by carynrich » Fri Apr 05, 2013 6:24 pm

I got mine from futurelec. They have a LOT of obscure resistor values in 1% increments. Eg, 3.83, 3.9, 3.92, etc.

http://www.futurlec.com/Res14WMetal.shtml

I've built two and they're pretty cool. Lots of front panel wiring though.

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Post by andrewF » Fri Apr 05, 2013 7:40 pm

3k9 is a standard "E12" resistor value
very common
I am sure Mouser etc have them.

Tayda is another good cheap source and ships in a day or 2 (unlike futurlec who need a couple of weeks)

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Post by synthcube » Fri Apr 05, 2013 8:09 pm

I have two of these mocking me from my backlog pile.
facebook: https://www.facebook.com/2SynthCube

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windspirit
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Post by windspirit » Fri Apr 05, 2013 8:26 pm

that 3k9 suggestion worked thank you, any suggestions for the 390 ohm or 820 ohm? I would be surprised not to find this stuff on mouser but for some reason it has been a challenge

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Post by logicgate » Fri Apr 05, 2013 8:28 pm

I was able to track down every component for this project very recently, I didn't have any trouble sourcing the components, I believe I got half at tayda, half at mouser and a couple of stuff from smallbear.

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windspirit
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Post by windspirit » Fri Apr 05, 2013 8:50 pm

ok i guess i was just being lazy and wanted to get all my stuff from mouser (which usually cuts it) but you are right I should go for the other sources also.

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Post by emdot_ambient » Fri Apr 05, 2013 10:27 pm

windspirit wrote:that 3k9 suggestion worked thank you, any suggestions for the 390 ohm or 820 ohm? I would be surprised not to find this stuff on mouser but for some reason it has been a challenge
Metal film, 1%

390
http://www.mouser.com/Xicon/Passive-Com ... s8Z1z0x6r9

820
http://www.mouser.com/Xicon/Passive-Com ... s8Z1z0x74y

Sometimes Mouser can be a pain, but I've never really not been able to find a resistor there.

I generally use their Xicon series of 1% resistors. This is a link to the filter selection where I found the above:

http://www.mouser.com/Xicon/Passive-Com ... s8Z1z0wljo

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Post by CJ Miller » Fri Apr 05, 2013 10:31 pm

windspirit wrote:ok i guess i was just being lazy and wanted to get all my stuff from mouser (which usually cuts it) but you are right I should go for the other sources also.
You can, but this does not mean that Mouser does not have them. It sounds like you have yet to click with how their search works. They do have 390 and 820 ohm resistors.

271-390-RC
271-820-RC

The "271-XXX-RC" is their number for Xicon 1%, 1/4 Watt metal film resistors. Just substitute the middle bit for what values you are looking for. 271-47k-RC, 271-2.2m-RC, etc. Since I often buy resistors from them, I just type it in directly.

Another way to do it is by navigating through their product listings. This can help when something is listed differently from my searches. For example, near the top left for the resistor listings, there is a category guide:
All Products > Passive Components > Resistors > Film Resistors >
Metal Film Resistors - Through Hole
To find things, just start by clicking "Products" on the blue bar, and select ALL PRODUCTS.
Image
Then scroll down the list, in this case, to Passive Components > Resistors.
Image
Then you should see their parametric search box which can be used to select more specific details.
Image

Usually now I will start looking through their products this way, and only do a regular search in the few odd cases that I still can't find something. It has saved me a lot of time.

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Post by emdot_ambient » Fri Apr 05, 2013 10:35 pm

I haven't looked at the BOM for this project. What kind of tolerances and wattage are they calling for?

You can always use a smaller tolerance in places where BOMs call for larger tolerances (as in you can always use a 1% where they call for a 5%). There's really no reason to buy 5% tolerances nowadays, though, 'cause when you can get 200 1% resistors for $4...are you really going to save much by buying 5% resistors?

However, if the BOM calls for higher watts than 1/4, then you'd best pay attention to that 'cause it means the circuit's drawing more power lower wattage resistors will get burnt out.

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Post by sduck » Fri Apr 05, 2013 11:15 pm

I got all the parts except for one chip from mouser. Not even hard to find stuff, those resistors and such. Do you have a paper catalog? They're all listed in it.

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Post by windspirit » Fri Apr 05, 2013 11:28 pm

^ good to know about the tolerances. I do not have a paper catalog, their online search can be a bit overwhelming sometimes. I click the wrong thing and i end up with a bunch of resistors the that look like nuclear fuel rods or something. Ill get them to send me a catalog, thanks for the help and direction.

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Post by sduck » Fri Apr 05, 2013 11:38 pm

Yes, using the online search form can be hit or miss. I always end up with smt parts by mistake whenever I rely on it too much. Anyway, I just go to the KOA Speer 1% Metal Film Resistor page ands order from it. They've got 3.92K, which is close enough. Similarly for the others - 392 Ohm and 825 ohm.

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Post by jumunius » Sat Apr 06, 2013 1:30 am

windspirit wrote:^ good to know about the tolerances. I do not have a paper catalog, their online search can be a bit overwhelming sometimes. I click the wrong thing and i end up with a bunch of resistors the that look like nuclear fuel rods or something. Ill get them to send me a catalog, thanks for the help and direction.
Another Mouser tip is, once you have selected an item that works (such as the KOA Speer 1% or the Xicon Metal Film both recommended above), there is a big box that shows each spec as a line item, and there are checkboxes next to each. Check anything that seems relevant (you'll learn this over time), but leave the value empty (be it resistance, capacitance, whatever) and then at the bottom click on "Show Similar". Then you see a list of all the other values of that series.

Well, that would be a little overwhelming with resistors, which come in a gazillion values, but it's the best way to shop for capacitors. Overall it's best to find a series that works and pick as many items from it as possible because it eliminates the likelihood that you'll forget to check the product dimensions one time and end up with the largest resistor ever made.

The print catalog will help with that though.

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Post by Revok » Sun Apr 07, 2013 12:35 am

I'd avoid Futurlec for anything really. I cant say I've ever been too happy after ordering with them.

Mouser, Digikey, Newark, Allied, and Arrow have all been good experiences.

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Post by Luka » Sun Apr 07, 2013 1:31 am

futurlec is pretty good for people who have time and struggle with sites like mouser. their site is much easier to navigate imo

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Post by scozbor » Sun Apr 07, 2013 4:11 am

I have my board and all parts (i think) ready to go, and its next my next build. But now I'm having second thoughts! It's just so damn big for 1 voice :despair:

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Post by emdot_ambient » Sun Apr 07, 2013 8:11 am

The only issue I've ever had with futurlec is that it takes like a month to get anything from them.

Seems like they ship stuff via a slow boat from China . . . wait a minute . . . :doh:

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Post by Synesthesia » Tue Sep 10, 2013 3:32 pm

Elby seems to do a component kit for it ... I just have the pcb so far ... need all the parts!

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Post by windspirit » Tue Sep 10, 2013 3:45 pm

Aus to Ireland shipping must be pretty high :/

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Post by Thonk Support » Tue Sep 10, 2013 4:14 pm

It's really worth persevering with Mouser and getting used to it. jumunius has the best advice for that.
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Post by qfactor » Mon Jun 09, 2014 7:59 pm

I've purchased a couple of MPS PCB and have been asking around if it's ok to power it up on +-12v instead of 15v? Do I need t change any resistor values to make it 12v "compatible"? :hmm:

Also, my PCB is ver 107 and would it be right to say that this version does not have J19 thru 21 connectors?
Thanks! :tu:

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Post by sduck » Mon Jun 09, 2014 10:35 pm

Look here - http://electro-music.com/forum/viewtopic.php?t=21279

Besides looking, asking there would be a good idea, as it's sort of home base for this project.

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Post by qfactor » Tue Jun 10, 2014 10:27 am

sduck wrote:Look here - http://electro-music.com/forum/viewtopic.php?t=21279

Besides looking, asking there would be a good idea, as it's sort of home base for this project.
Yes, I know that link! :tu: went thru all 30 pages of it some weeks ago. Also left another message in that same link some 2 weeks ago, and I'm still the last person in that thread, presently! :eek:
Also, left a PM for Scott about this around the same time.
That's why I bumped up this thread here, as the place looks rather deserted in the DIY section :despair:
Thanks for it, anyway :tu:

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Post by StillNotWorking » Tue Jun 10, 2014 10:43 am

One day I will eventually drill holes in this panel....

Image

Until then I play with it in my image editor :bang:
Image

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