[TriEmbed] bad news about decade resistor boards

[Pete Soper]

On 10/15/2016 01:51 PM, Robert Gasiorowski wrote:
> 1% resistors are between $0.005 to $0.01, 0.1% are 10x-25x more.
In your dreams. Look up the price of, for example, 1210 size 1/2 watt 
resistors with values of 11 through 19 ohms. You'll find them slightly 
higher cost. Like a few hundred times higher.

You didn't read what I wrote. I said that because the required values 
are NOT E96 they are much more expensive.

Feel free to use octopart, but results for that search engine were less 
than pitiful when I tried it just now. Here's what Digikey offers for 
the 11-19 ohm values. Notice only a subset are available, and for a 
single package size, a smaller subset.

http://www.digikey.com/product-search/en/resistors/chip-resistor-surface-mount/65769?k=resistor&k=&pkeyword=resistor&v=10&pv7=2&pv1=1080&pv1=1081&pv1=1083&pv1=1084&pv1=1085&pv1=1086&pv1=2370&pv1=1087&pv1=3655&pv3=1&pv2=5&FV=fff40001%2Cfff800e9&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25


Mouser's offerings are not as good.

Notice the few values Digikey and Mouser offer are automotive. I guess 
something drives those guys to avoid standard E96.

Again, I'm asking you *where* one would find these magically inexpensive 
resistors in 1210 size with the 63 values required?

Instead of wondering if it would take me an hour or more to "design" a 
copy of a completely regular PCB like this, I'll point out that it only 
changes one of the product terms: the other one is still assumed to be zero.

-Pete


> You don't need E96, those decades use 1R, 10R, 100R, 1K, 10K, 100K, 
> and 1M values only (each *10)
> I can design board like that in less than an hour, just need to know 
> dimensions.
> You can use through hole or SMD and I would not do them myself, I 
> would pay fab house to solder them, $0.04 per pad TH and $0.03 per SMD.
> Soldering headers would add $5.60 (without discount,) but anyone could 
> solder them at home.
>
>
> On Sat, Oct 15, 2016 at 12:13 PM, pete at soper.us <mailto:pete at soper.us> 
> <pete at soper.us <mailto:pete at soper.us>> wrote:
>
>     Where are the 1% 1/2 watt resistors with the required values for a
>     few cents each? In my experience stepping away from E96 values
>     gets pricey, assuming you can find a source at all. Then there's
>     the notion of the time to design the board, get it and a stencil
>     made, paste and pick and place the parts and solder it, then add
>     the barrier strip. So that's $0/hr for labor and magical sources
>     for parts.
>
>     Pete
>
>     ----- Reply message -----
>     From: "Robert Gasiorowski" <rgresume at gmail.com
>     <mailto:rgresume at gmail.com>>
>     To: "Pete Soper" <pete at soper.us <mailto:pete at soper.us>>
>     Cc: "Triangle Embedded Computing Discussion"
>     <TriEmbed at triembed.org <mailto:TriEmbed at triembed.org>>
>     Subject: [TriEmbed] bad news about decade resistor boards
>     Date: Sat, Oct 15, 2016 9:31 AM
>
>     It would probably cost less if you made them yourself, and that's
>     including assembly!
>     You could make them custom size, so that they fit the box of your
>     choice.
>     You could also use higher precision resistors (0.1% or better) for
>     1k, 10k, and 100k, to make your decade box even better.
>     High precision resistors are expensive, but in bulk might not be
>     that bad.
>
>     On Sat, Oct 15, 2016 at 8:55 AM, Pete Soper via TriEmbed
>     <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>
>         Just a few folks expressed interest in the decade board a
>         while back. I thought it might be more interesting mounted on
>         a laser-cut acrylic base and I wasted some time exploring
>         these and other cute accessories. In the meantime the price
>         was jacked up to $14 +$3 shipping each. I searched around and
>         couldn't find the quantity five deal Paul pointed us too
>         either. I was going to just get a bunch on spec and coordinate
>         with Jeff to offer them in return for Splatspace donations.
>         But at this price they're no longer interesting. Here's the
>         item in question:
>
>         https://smile.amazon.com/Electronics-Salon-1R-9999999R-Programmable-Resistor/dp/B01CZLPAOM/ref=lp_8937979011_1_3?srs=8937979011&ie=UTF8&qid=1476535329&sr=8-3
>         <https://smile.amazon.com/Electronics-Salon-1R-9999999R-Programmable-Resistor/dp/B01CZLPAOM/ref=lp_8937979011_1_3?srs=8937979011&ie=UTF8&qid=1476535329&sr=8-3>
>
>         -Pete
>
>
>         _______________________________________________
>         Triangle, NC Embedded Computing mailing list
>         TriEmbed at triembed.org <mailto:TriEmbed at triembed.org>
>         http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
>         <http://mail.triembed.org/mailman/listinfo/triembed_triembed.org>
>         TriEmbed web site: http://TriEmbed.org
>
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.triembed.org/pipermail/triembed_triembed.org/attachments/20161015/4cfe595f/attachment.htm>