Dangerous Prototypes

I've been quietly slaving away on a project with the folks at Oomlout in the UK called OOMP. I forget what it stands for, but it's an open parts library and component management system. There's a standard format for naming things, a webpage for each part with open source footprints, renderings, graphics, etc. The cable and other bundles are just a tiny part of what may become a giant line of components.

A few weeks ago I finished the PHP scripts that build the website from a ton of part definition XML files. You can see the bare bones beginnings here.

This is the list of individual parts currently included:
http://dangerousprototypes.com/oomp/partIndex.html (http://dangerousprototypes.com/oomp/partIndex.html)

This is a list of bundles using the parts, like our cable bundle:
http://dangerousprototypes.com/oomp/bundleIndex.html (http://dangerousprototypes.com/oomp/bundleIndex.html)

You can also see some bare bones documentation of the naming system, etc.

When I finished this code, which was fun but not always inspiring, I had a flash of excitement. Let's make a BOM in OOMP format. We can release our project partlists as OOMP BOMs and have a webpage that links to details about each part, generally making it easy to order parts and find replacements. In time we're going to take it a step further so the page can order bundles including all the parts -*and PCBs*- you need to complete the project *with one click*...

So here's the OOMP BOM tool:
http://dangerousprototypes.com/oomp/oompBOM.html (http://dangerousprototypes.com/oomp/oompBOM.html)

It's completely client side javascript so I don't have to worry about system security and it scales extremely well. Drag the attached .OOMP file onto the page (you'll need a modern browser) and it will show some info, links, and the hypothetical part list for the Bus Pirate. It's not really the Bus Pirate yet, just some crimp housings from the first part bundle I'm using to test the system.

So in addition to the cable bundles, LED bundles, and other fun parts, we need some dead simple stuff to fill in like resistors and capacitor kits. I've been struggling with the best way for *us* to do it.

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Part of me wants a complete set of E24 resistors from 1R to 1M (147 values, 1% tolerance). Similar for capacitors, like this book Eric gave me a few years ago (92 values, 0.5pF to 10uF) or the polish set (65 values, 0.47uF to 1uF). But that's overkill for us, we work with 4 or 5 typical values, and its expensive. And if you really need this set, you can grab one on ebay, amazon, taobao for a few bucks so there's little profit in it other than making our system 'complete'.

A big part of me is leaning towards a reduced set, similar to the "50 resistor values and 32 capacitor values" available on ebay for a few bucks. Put them in a nice book with the OOMP part numbers and it satisfies everything I've ever needed at a fraction of the cost, weight, labor, etc of the full E24 or E12 sets. Fill it in with bulk 0.1uF, 1uF, 10K, 1K, 330ohm and you have everything we use for digital prototypes. I need maybe a 12K resistor or .22uF (which is usually 2x0.1uF on my boards) occasionally for USB on a PIC or similar, thats about the only time I dip into the resistor kit.

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With the small reduced sets we can make a combined R+C book that's classy and cheap. One for 1206,0805,0603,0402. Four books will fit into an OOMP part box, so you have a decent library of parts in common sizes in a neat little tray.

Continuing below...

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So I have two major questions:
1. What values? 50 or 63 resistors. 17 or 32 capacitors?
2. How many? 25 or 50, or 25 of most and 50-100 of common values

Values
Two sets seem to be popular on Taobao and Ebay. 50 resistor values (which misses some common ones like 15K) and 32 capacitors, and a set of 63 resistors and 17 capacitors. Maybe the best of both with 63 resistors and 32 capacitor values? Aside from a 555 or passing FCC testing who really uses odd cap values these days in hobby electronics?

A set of 50 resistor values:

 0R, 1R, 4.7R, 10R, 22R, 39R, 47R, 68R, 75R, 100R, 120R, 150R, 220R, 330R, 470R, 680R, 1K, 1.5K, 1.8K, 2.2K, 3.3K, 3.9K, 4.7K, 5.6K, 6.8K, 8.2K, 10K, 12K, 22K, 33K, 39K, 47K, 56K, 68K, 100K, 120K, 150K, 180K, 220K, 270K, 330K, 390K, 470K, 560K, 680K, 1M, 2.2M, 3.3M, 4.7M, 10M.

63 values:

0Ω 1Ω 1.2Ω 1.5Ω 2Ω 2.7Ω 3.3Ω 4.3Ω 5.1Ω 6.8Ω 8.2Ω 10Ω 12Ω 15Ω 20Ω 27Ω 33Ω 43Ω 51Ω 68Ω 82Ω 100Ω 120Ω 150Ω 200Ω 270Ω 330Ω 430Ω 510Ω 680Ω 820Ω 1KΩ 1.2K 1.5K 2KΩ 2.7KΩ 3.3KΩ 4.3KΩ 5.1KΩ 6.8KΩ 8.2KΩ 10KΩ 12KΩ 15KΩ 20KΩ 27KΩ 33KΩ 43KΩ 51KΩ 68KΩ 82KΩ 100KΩ 120KΩ 150KΩ 200KΩ 270KΩ 330KΩ 430KΩ 510KΩ 680KΩ 820KΩ 1MΩ 2MΩ

63 values is not only more comprehensive, it doesn't load up with little used values in the Mega ohm area.

A set of 32 capacitor vales:

2.2pf, 3.3pf, 4.7pf, 6.8pf, 8pf, 10pf, 12pf,15pf, 22pf, 33pf, 47pf, 68pf, 100pf, 150pf, 200pf, 220pf, 330pf, 470pf, 680pf, 1nf, 2.2nf, 3.3nf, 4.7nf, 6.8nf, 10nf, 15nf, 22nf, 33nf, 47nf, 68nf, 100nf, 1uf.

17 capacitor values:

15pF 22pF 27pF 33pF 47pF 68pF 82pF 100pF 120pF 150pF 180pF 220pF 1nF 10nF 100nF 470nF 1uF

The 32 value set has more in the very low end. Neither have up to 10uF (in the book eric gave me we have 2.2 4.7 and 10uF), which I'd like to include but can be expensive.

How many
The cheap part books and pages available in China hold a strip of 25 pieces. The sets from ebay/etc are strips of either 25 or 50. The capacitor book Eric gave me has two rows of 25 of each value. A total of 50 feels really nice, but with 50 values that's 6 values per page or:
9 pages of 50 resistors and 6 pages of 32 capacitors. A total of 14 if they overlap. (4mao x 14pages= 5.6RMB for pages)
11 pages of 63 values and 6 pages of capacitors. A total of 17 (6.8RMB)

14RMB for the book, about $3 in supplies just to hold the parts. Add parts + labels + labor.

Halving the count to 25 each value doesn't save a lot on pages, but probably saves a lot on labor and labeling. Depends if we cut and label each strip ourselves, or if we find someone to do it. Looking into this now. Precut sets of 25 are about 9 bucks on ebay, or 18 if we use 50 of each value (obviously a little misleading...). Cutting ourselves is about half that in cost, plus who knows how much on labor.

I have a feeling 25 each is a good number. If you need more than that, its not just a single value, order a bunch. We can supplement the books with mini reels or actual reels of common values (the OOMP tray doubles as a handy reel hanger too!).

Conclusion
I'm just trying to get this straight in my head. Next step we'll contact a bunch of suppliers and see how much it'll cost to cut sets and stamp the value on the back. there seems to be a machine to do this and the sets are really cheap. That'll probably inform what happens next, but the best info will come from you. What do you want to see?

Regarding the resistorvalues the 63 seems more usable then the 50 and is more consistant: every decade has the same values (1, 10, 100, 1.2, 12, 120 etc ). I dunno how well you could use these values to make other values (series/parallel).

Regarding capacitor values the 17 seems more usable. Personally i only use 22p/27p for xtals and 100n, 1u for supply rails (mostly a 100n and a 10u tantalum). So i dont really care about different capacitors :)

Regarding quantity i would say 25, as it is for prototyping. Most used values (0, 33, 1k, 10k) double or quadriple that amount.

As an extra I would make a combined 'digital' book as most of the audience is digital oriented, with just the 'digital' values in it: 0 for bridges, 33/100 for input protection, 1k for leds/strong pullups, 10k for regular pullups (perhaps some other USB resistor values?!) 22p/27p for xtals, 100n/1u/10u for decoupling and some 2.2u and 10u tantalum 6V3/10V. As an extra red, green, yellow, blue and white leds (just the small ones for indication), ferite beads and some polyfuses (100mA and 1A). About 100 pieces each.

I also like to see the books and sheets sold seperately as I have allready some strips lying arround :)

+1 for an digital version
Isn't it an comon set of caps used for vregs also?, have built some kits for pic etc, and thos use versious 5v and 3v3 vregs with an arangement of some caps that seems to be used often (but probably not for the smd versions?)

I'm surprised you haven't mentioned buttons.  Momentary and toggle.  These seem to be the least standardized and hardest to match up.  Matching up one of the ebay button kits with a set of eagle symbols and oomp part numbers would be awesome.  Same for barrel connectors, and sil/dil smd pin headers. All these parts are fairly non standard so the guarantee of a match to a eagle symbol is a sure sale for me. 

I would be cool to see some hackspace sized passive kits too.  Something with say 200 of each value perhaps (probably just quantity pricing on the books above).

Also consider stocking empty books and packs of the pages separately. These are quite expensive on ebay, as above it would be great to be able to buy pages and insert them into local binders (makes shipping cheaper).  Perhaps also some a4 wide and letter height sheets?  (being the smallest dimensions of the two standards and thus able to fit either binder).

I ran a 16 person bus pirate build at our hackspace, was very popular (sold out early actually).  You might consider 10 person kit sets of the bp for hackspace build nights.  SMD kits are hard to come buy - the objective being to learn to solder, not so much to save money.  My LTS bpv3 is open h/w if you want it ;-)


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FWIW, I made up my own resistor series (for my own use, I don't bother selling resistors, too much work cutting strips, too little profit).

Anyway, because I'm cheapo, I didn't want a full series, and equally I wanted to choose my own values that would be most useful for hobby purposes, I don't mind using 2-3 resistors to get a close value, or just using the closest one I have.

I also put thought into "useful" values, especially for LED current limiting.

I also don't really like fiddling with strips, so I didn't want a folder of strips.

So anyway, these are the values I came up with:
6 decades each of 1, 1.5, 2.2, 2.7, 3.3, 3.9, 4.7, 5.1
and some extra specific values 120R, 180R, 240R, 300R, 360R, 430R, 1M
total 55 values, and I stocked with 100 of each.

I store them in two pill boxes as in the attached.  I have 1 compartment left over, 10M might be good there.

Of course, most of the common values are there, 4.7, 2.2... but I use this set along with my resistor paralleler (http://http://sparks.gogo.co.nz/resistor_paralleler.html) if I need to get something close to a calculated value, generally 2-3 resistors parallel gets well within a percent.  I started off with a smaller set  (basically skipping out every other value-series) but that made it too difficult to get close values a lot of the time.

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Great stuff, thanks everyone. We're getting quotes on 63 resistor values and 20 capacitor values. It looks like we'll need to kit them ourselves because nobody seems to be able to customize them for us. There must be a factory doing this somewhere in china, but they're not selling direct on Taobao...

We also sent a SMD reel sample to a electronic tape dispenser company, they're going to see if their machine can spit out cut length strips for us lol, though the cheapest thing may still be a unistudent with a pair of scissors.

As an extra I would make a combined 'digital' book as most of the audience is digital oriented, with just the 'digital' values in it: 0 for bridges, 33/100 for input protection, 1k for leds/strong pullups, 10k for regular pullups (perhaps some other USB resistor values?!) 22p/27p for xtals, 100n/1u/10u for decoupling and some 2.2u and 10u tantalum 6V3/10V. As an extra red, green, yellow, blue and white leds (just the small ones for indication), ferite beads and some polyfuses (100mA and 1A). About 100 pieces each.

I'm defo working on a DP parts book or box. Strips of 100 of our "red drawers" parts: R, C, NPN, PNP, LEDs, Xtals, ferrite beads, etc.

Matching up one of the ebay button kits with a set of eagle symbols and oomp part numbers would be awesome. Same for barrel connectors, and sil/dil smd pin headers. All these parts are fairly non standard so the guarantee of a match to a eagle symbol is a sure sale for me.

This is the meaty, juicy, fun part :) That's the main point of OOMP, but we need to quickly fill in the edges too. SMD and PTH C and R kit will make 50%-80% (guessing) of any project build-able with OOMP parts. Picking switches, building footprints, that's the fun stuff I get to do in Huaqiangbei :)

If you just rack up the reels on a bar fixed to the wall, and have a measuring stick, it would be pretty quick to slice off the appropriate measured length of tape for each reel.

If t'were me, I'd make it a DIY kit, send the tapes, the folder, and printed value stickers, let the customer file the tapes into the folder and stick on the stickers themselves, that's the very time consuming part, cutting the tapes would be a 5 minute job if you've got it setup.

But then you have to mark the tapes so the customer can identify which is which, not that easy on smd..
and make sure that the tapes are packed so they don't rub to each other and loose the covering tape.

A reel cutter is something I've wanted to build for a while - like Mr Bitey but for SMD parts.

Best would be a combination cutter/inkjet, to cut reels into labelled lengths. Madame Chompy-printy.

Madame Chompy-printy

Cute :)

63 resistor reels just arrived for a test 0603 OOMP part book. Books and sheets should be here tomorrow. We'll stuff some samples and get an idea of the time involved this weekend if everything goes smoothly.

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If you can source the pages supporting larger width tapes, that's something I'd buy.  I spent a good amount of time looking online for SMT book/binder pages that are wider than the standard 8mm resistor kit pages.  Adafruit sells a blank book, but only one page is larger (24mm), and I need a lot more than one, and would like even wider if available.
http://www.adafruit.com/products/520 (http://www.adafruit.com/products/520)

OMG! I know exactly where her books and pages are made, and I know exactly who makes the book she's reselling. LOL. I didn't know they had one. I've been looking all around at what people do and settled on that basic mix too after seeing it on taobao, amazon, and ebay. I guess Adafruit likes it as well. Yeah :) And they give us a price to go by. I was thinking a bit less than that, but ok :) I'm beefing it up with more values though, especially the capacitors.

I bought Adafruit's 0603 book and thought the $35.xx price was reasonable.

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I came up with this jig for cutting resistors for books, and a value stamp is also on the way, but it's just too slow. About 15 minutes for one guy to cut a reel (two days to cut parts for 100 books) and who knows how long to stamp values on them.

This afternoon I'm going to visit my test rig guy to see if he can make the physical part to hold a reel, advance it with stepper motor, cut it, and stamp it. I'll put the electronics together and run it by arduino or something stupid. I think this is the best way to go, it's fun, and good PR.

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This is the design for a multiple position stamp. It's being made custom by a taobao company for 150RMB (~$25). It can do various values of capacitors (pF,nF,uF) resistors (R,K,M), inductors/ferrite beads (uH), power (mA) and lengths (mm, cm). Forgot to include crystals (kHz, MHz).

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I didn't see you mention it, but you know there are machines for this, right?
http://www.alibaba.com/trade/search?fsb ... achine+smt (http://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&SearchText=automatic+tape+cutting+machine+smt)

At roughly $3000 US each, probably out of your budget for getting started, but maybe you can buy machine time from a factory that has one or something.

If your jig is automated, and just takes user time to swap reels, it's probably fast enough if whoever is running it multitasks.