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24412Re: [nslu2-linux] Re: Temperature sensors and A-D converters

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  • Thomas Cooper
    Apr 5, 2010
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      It's much easier to buy what you need ready to go from Spark Fun Electronics, or some place similar... They cost about a buck or so. A bottle of ferric cloride will cost you more than that.

      On Mon, Apr 5, 2010 at 4:09 AM, clerew5 <clerew5@...> wrote:

      --- In nslu2-linux@yahoogroups.com, Mike Westerhof <mwester@...> wrote:

      > > But I did not check enough. It turned out to be a SOT23 style chip which was about the size of a baby's fingernail :-( . Not nice for building on a breadboard. I looked for a suitable breakout board, but the only available one for an 8-pin SOT23 was in California, and I am in the UK. The only breakout boards readily available in the UK are for 6-pin SOTs (well, there is a possible one from Microchip, but at a ridiculous price).
      > >
      > > So back to the Farnell website for a chip with a larger footprint. But they all seem of be surface mount and with TSSOP or MSOP format, where the pin spacing is still 0.025in (the same as SOT23).
      > >
      > > So can anyone suggest any better chip? I might get away with SOIC format (0.05in spacing). The only chips I can find with good ol' DIL fomat are from Microchip, and they use Yet Another Nonstandard Interface (Microport).
      > >
      > Check out the kits and parts at the supplier I listed above. That will
      > give you some idea about size and nature of the various one-wire chips
      > and devices, and from that you can decide if the one-wire parts are more
      > practical.

      Yes, there seems to be some neat stuff there. But I am already well down the i2c route.

      Actually, I have now reached the conclusion that the easiest way to embed surface mounted chips (even the very small ones) is to manufacture a one-off PCB. This turns out to be much easier that one might have thought. Google turns up lots of advice. All you need is a laser printer, some suitable transfer paper (old glossy magazines are recommended), and a willingness to handle ferric chloride etch (which is pretty messy stuff by all accounts).

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