[TriEmbed] bad news about decade resistor boards

Sat Oct 15 20:41:28 CDT 2016

Few examples after quick search (US stock obviously more expensive, but
still under $0.10/pcs) You would buy in CN since my suggestion was to
assemble then in CN. After discount on bulk order, prices will be lower.

https://www.aliexpress.com/store/product/Free-shipping-100pcs-SMD-resistor-1-2010-10K-Ohm-2010-Resistor-10K/511081_1478473230.html
https://www.arrow.com/en/products/2-1879536-9/te-connectivity-ltd
https://www.arrow.com/en/products/rk73h2ettd1003f/koa-speer-electronics
https://www.arrow.com/en/products/erj-p06d1002v/panasonic

What I meant is you don't need a range of E96 values, all you need is one.
And since when 100 is NOT E96?

Now, using 10K and up 1/2W resistors does not make sense, unless you plan
to work with high voltage (>50V,) so I think 1/4W (10K, 100K, & 1M)  are
more than enough. Going the other way, I think it makes sense to use higher
wattage resistors, especially 1R and 10R (use TH instead of SMD if that
makes sense.)
The specs of the board you want to get claim 1% with 1R step, which is a
total bull. Go above 100R and 1R step is incorrect and useless. For
example, 10K resistor could actually be 101K or 99K, so first 3 decades
(1R, 10R, 100R) are useless. This is why I suggested using higher precision
resistors for 1K and up.

And finally, the price difference between both boards would be so small, it
makes sense to go that extra mile and make a board that actually makes
sense.

Just my $0.02

On Sat, Oct 15, 2016 at 2:40 PM, Pete Soper <pete at soper.us> wrote:

> 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 <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>
>> To: "Pete Soper" <pete at soper.us>
>> Cc: "Triangle Embedded Computing Discussion" <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> 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-Progr
>>> ammable-Resistor/dp/B01CZLPAOM/ref=lp_8937979011_1_3?srs=893
>>> 7979011&ie=UTF8&qid=1476535329&sr=8-3
>>>
>>> -Pete
>>>
>>>
>>> _______________________________________________
>>> Triangle, NC Embedded Computing mailing list
>>> TriEmbed at triembed.org
>>> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
>>> TriEmbed web site: http://TriEmbed.org
>>>
>>
>>
>
>
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