Knowing How to Source Components

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vrfats
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Knowing How to Source Components

Post by vrfats » Tue Jan 18, 2011 11:15 pm

Hi I'm deciding to have a go at Eurorack DIYing via CGS.
Really my first time sourcing my own parts...
(I've built a few pedal kits and hacked/modded some things a bit, burnt myself on a soldering iron a good deal, had a few introductions to bread boarding but not all of it has sunk in all the way...)
...anyhow I was starting to look up the parts via Mouser and Allelectronics and was overwhelmed with 100s of options for an 18pF capacitor...
Now okay I've read Ken Stones disclaimer that if you dont know how to source the parts then this is not for you... ...but I'm stubborn and determined and once I do have the parts I know how to get them on the friggin board...
also I have a few knowledgeable heads I can run to for help if I get in a jam.

anyhow anybody have any resources guidelines for part selection as it relates to synthesis...

specific example, I see my options for an 18pF cap are:
Passive Components
• Aluminum Electrolytic Capacitors (1)
• Ceramic Capacitors (1,243)
• Mica Capacitors (59)
• Trimmer / Variable Capacitors (6)

I'm planning on building a VCO, a wavemultiplier, a DUSG and some Multiples...

:nana:

thanks in advance for bringing my daydreams of modulemaking closer to fruitition

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decaying.sine
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Post by decaying.sine » Tue Jan 18, 2011 11:24 pm

I feel you here. Have no fear though. You're only risk is burning your fingers, magic smoke, and possibly death if you are working with mains :hihi:

Resistors are the easy part. Just get all metal film 1%. They are cheap if you buy in bulk. I only get 5% (the tan ones, generally) for more obscure values that don't have 1% readily available. Get yourself a IC sockets. Search EVERYWHERE for bill of materials. Bill and Will at dragonfly alley have many. There are a bunch of others on sites and forums. Dig deeply for your specific build.

I always find capacitors to be a pain in the ass. You can always be sure of electrolytic bypass caps near the +/- VDC inputs. There are other rules of thumb. Someone gave them to me over at EM. I'll go dig them up and post for you...
Brian
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Post by decaying.sine » Tue Jan 18, 2011 11:41 pm

Here was a rule of thumb that someone posted over at EM...

for small values (pF): ceramic
for bigger values (nF): polyester
and even bigger values (above 1µF): elcos

This is unless otherwise specified.

Once you start getting more familiar with mouser or your preferred vendor, you'll figure out how to order quickly. I use mouser and generally just xicon 1% resistors. Not because they are best but cheapest, but just because.

If you are doing a specific build, search everywhere (mostly muff's and EM) for others builds. This shit is complicated, and we are all proud of our DIY efforts. That means lots of pics are shown so you will often have resident expert examples of the stuffed and working PCBs. This is really helpful. Also, if you buy PCBs from Ken Stone, prep a good question for him and he will answer you. Same with all the other "creators." These are all really good people who want you to make some noise.

I always feel like caps are the hardest. For ICs, I generally read the datasheets for all the weird variants and just select the most available best priced one.

I also have a little trouble with pot selection mostly because of sizes of shaft, bushings, and all that other stuff. I usually save that for last and just get what everyone else has.

If you have specific questions on wire, solder, soldering iron, etc. People have already come up with good options so check out the threads at Muffs.

If you start building your DUSG and post your pics in the DIY section, I'll start stuffing mine too. I have two CGS114 that I need to stuff. Also, me and dude are going to be stuffing some CGS75's and we'll likely share our results, good or bad.
Brian
"I must create a system or be enslaved by another mans; I will not reason and compare: my business is to create." William Blake

"Vactrols ringing, Dude." "Thank you Donny"

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decaying.sine
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Post by decaying.sine » Tue Jan 18, 2011 11:42 pm

Also, welcome! :party:
Brian
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vrfats
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Post by vrfats » Tue Jan 18, 2011 11:44 pm

Thanks a ton should be a lot of help :hihi:

oh yeah what would the range in terms of big and small values be generally...

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Post by vrfats » Tue Jan 18, 2011 11:49 pm

oh
pF
nF
µF
gotcha shoulda payed more attention :hmm:

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Post by vrfats » Wed Jan 19, 2011 12:06 am

one final (well maybe not) question:

Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 25volts 18pF C0G 20%

is that the maximum voltage the part can take, recommend voltage for the cap or something else?

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decaying.sine
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Post by decaying.sine » Wed Jan 19, 2011 1:04 am

yeah. 25 volts is the max it can withstand, with some error of measurement in there. 18pF the capacitance and 20% the tolerance for capacitance measurement (ie., amount it could vary around 18pF in a specific lot).
Brian
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Post by Paradigm X » Wed Jan 19, 2011 9:09 am

Hmm.. i bought a cheap pack of 5% resistors to get me started... was this a bad idea?

Other than oscilators, which need perfect pitch, if im building other units whats the implications of using 5% ?

I thought a bit of tolerance would add up nicely to the analogue roughness im after, having been all ITB for years.

Cheers

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Post by e-grad » Wed Jan 19, 2011 9:24 am

Paradigm X wrote:Hmm.. i bought a cheap pack of 5% resistors to get me started... was this a bad idea?
No! For most applications they will be just fine. If not it will be stated in the documents.

However, for the average hobbyist it is logistic challange to stock resistors of various different values in a way that they are at hand. Stocking each value twice (1% and with 5% tolerance) even more so.

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Post by Paradigm X » Wed Jan 19, 2011 9:51 am

Thanks!

Looking back they were only £6 for the whole pack (640 resistors) so no major loss.

But good to know theyre ok for most things. I thought theyd be fine for distortion boxes etc.

They did come all in one package with no labelling tho :lol: - will take a while to sort em out.

Cheers!

Ben

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decaying.sine
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Post by decaying.sine » Wed Jan 19, 2011 9:58 am

Like e-grad said, they are usually fine unless otherwise specified.
I like getting the 1% because I buy them in bulk and it makes it easier to match them to a tolerance of 0.1% when needed. This is usually only for more typical values for the most part so ordering 1% is probably more out of habit than necessity. I like the pretty blue color better too!
Brian
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Post by maskull » Wed Jan 19, 2011 10:54 am

See if you can source a catalog from whatever electronics supplier (Mouser, Maplin, Digikey, etc...) you are purchasing from.

I've found it much easier to thumb through a catalog rather than use the search functions on websites.

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Post by EATyourGUITAR » Wed Jan 19, 2011 11:13 am

as a general rule, when your on mouser for caps by category and there are 3456 poly film
and 23 variacs you want to click on the one that has more products in it. electrolytics are special and as a general rule you use them when the schematic shows a + or - on the cap or when it has a curved line.

1% metal film is important if you want your shit to sound like the next guys shit. if you got 20% you will have some stuff that doesn't do exactly what you thought it would. like building two pedals in a row and they sound totally different. metal film is a little more temperature stable as well.
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Post by russma » Wed Jan 19, 2011 11:21 am

vrfats wrote:one final (well maybe not) question:

Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 25volts 18pF C0G 20%

is that the maximum voltage the part can take, recommend voltage for the cap or something else?
"SMD/SMT" means it's a surface-mount cap, not a through-hole. Are you doing surface-mount? If there are holes in the PCB for inserting this cap into, you want through-hole.

Or was that purely an example?
Russ M.

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Post by pugix » Wed Jan 19, 2011 4:25 pm

CGS boards are through-hole designs. For pf capacitors, I buy Mouser, e.g. C410C180J1G5TA for 18pf. These are type C0G 100V 5%.

Capacitors can be a challenge because of so many different types. Be sure to check out Elby Designs for CGS kits. If you are doing Eurorack, these could be just what you need.

http://www.elby-designs.com/panther/panther.htm

Here are the CGS component kits:

http://www.elby-designs.com/shopping/index1.html
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Post by Peake » Wed Jan 19, 2011 5:25 pm

Please also be aware that transistors can lead to confusion...one company's version of a transistor might have a different pin configuration than another company's version; same name, same behaviour, different connections. You'll notice a little "f" on a unit for the manfacturer, Fairchild, and you can google for the Fairchild datasheet for your specific trannie...or if you have a tester it won't reveal any useful data until you seat the trannie correctly; make note of its pinout (ECB, etc.).

Welcome to DIY! There is a learning curve that never seems to end, but it's a wonderful love/hate relationship :)
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Post by vrfats » Wed Jan 19, 2011 5:36 pm

That was purely an example, but thats great to know...
So if you etch your own PCB you dont necessarily need to drill all those holes?
:eek:

thanks for the elby link i was expecting the kits to be more $, still not sure if i want to go that route.

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Post by fluxmonkey » Wed Jan 19, 2011 5:43 pm

check out bill & will's dragonfly alley pages... they've built and documented a shit-ton of modules, including some CGS, and their pages have lots of detailed bills of materials complete with mouser part numbers. even if they haven't built the module you're building, if you graze thru a few of their BOMs you'll probably find a part number for the item you're looking for.

i always order more of any component than i need for a specific build, and put the rest into stock... and then reorder using the same part number when i finally do run out. each designer seems to have some values or parts that they're partial to, so if you build a lot of CGS projects, you'll find yourself using the same trannies and cap values across multiple projects.
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Post by kindredlost » Wed Jan 19, 2011 5:48 pm

SMT sometimes gets pretty damned small as well and conventional soldering sometimes just doesn't cut it. I'd avoid it unless there is a need for a pocket sized modular synth. :eek:

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Post by vrfats » Thu Jan 20, 2011 12:51 am

there seems to be a lot more DIY resources formatted to MOTM (including cgs) but I've read that most of the cgs modules are +/- 5v and euro-able.
My main point of anxiety and uncertainty at this point is hooking the 16 pin power ribbon up to my bus from one of these. :deadbanana:

(I could've sworn I've seen a thread on formatting cgs to euro but search turned up nothing ...)

I noticed how panther "euroified" the cgs modules on there... it seems mainly for space / convenience marketability purpose, but if I recall correctly this included some alterations in circuitry... finding creative ways to squeeze these in a case doesnt seem too difficult

So once all the components jacks and knobs are on a +-5v board... Im guessing some people have hooked them into a euro case...?

Thanks for all the help guys, this thread is going to be a useful reference.

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Post by Luka » Thu Jan 20, 2011 12:56 am

i think your mixing up your facts

cgs modules are configures for 15v supplies but most will work at 12v

to make power cables you will need to get some ribbon and have the IDC connector at one and MTC at the other. easy

if i were you i would order some kits to begin with
get a good understanding what everything is
then venture into buying parts for yourself

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Post by iopop » Thu Jan 20, 2011 1:51 am

Think I've mentioned this in another thread, but if you get too many hits to handle, use another supplier until you get the hang of it. Small bear or Futurlec will cover most of your needs for a start.

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Post by cornutt » Thu Jan 20, 2011 10:10 pm

vrfats wrote:That was purely an example, but thats great to know...
So if you etch your own PCB you dont necessarily need to drill all those holes?
:eek:
No, the board has to be designed for either through hole or surface mount. If you are just starting out in DIY, you don't want to mess with surface mount yet. Those suckers are really small... :twisted:
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Post by frozenkore » Fri Jan 21, 2011 9:52 am

The only things I can add are try to order as much as you can from one source because if you're only ordering small amounts, shipping will kill you. Also, most importantly, go over your order before you place it, and then go over it again, then wait a day and go over it again.

Where this becomes important is when you're dealing with part size. I bought some electrolytic caps for a CGS board. One kind was rated for 50v the other 63v(?), the latter was twice (literally) the physical size of the other and was too big for the board. If I had looked over the sizes and measured the silkscreen on the board, I would have known that these weren't the capacitors I was looking for.

If you plan on doing a compact panel, make sure you measure your panel parts to make sure things will actually fit.

SMD/SMT: The only time I've come across these are on CGS boards for coupling capacitors, they suck to solder, especially the 1206 packaged ones -- they are tiny.

Lastly, if you don't feel like making conversion cables from the MOTM to Eurorack style, Mr. Mattson has you covered: Cable.
Cheers!
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