Member Since: August 26, 2010

Country: United States

  • For anyone trying to build a somewhat precise scale with this sensors please DO NOT use them. Their accuracy and repeatability is very poor, and the slope and offset varies a lot from sensor to sensor. I think you are better off hacking a body weight scale.

    If you're still interested, I used the following setup: 4 of these hooked up independently to an INA125 instrumental Op-Amp with about 10-20 ohms of resistor gain (depended on each sensor). A 5th sensor acted as the other half of the wheatstone bridge for each of the four load sensors. For each sensor I calculated an offset and a slope with 4 known weights, with linear fitting. Every output was connected to an Arduino analog pin, and I was averaging 10 samples before adding the weight of each sensor. I managed to get about 2kg of error over a range of 0 to 20kg, but that was way more error that what we needed.

  • Found it! The crystal is the CSTCE16M0V53-R0 from Murata, DigiKey PN 490-1198-1-ND.

  • Do you have the part number of the SMD crystal? It seems that you don't have it for sale and I can't find it in Digikey. Thanks in advance

  • Great post! Is there anyone who has already certified a product and could recommend a testing/certification facility?

  • Maybe I wasn't too clear. I meant that with the SPOT Connect you can only send but not receive data, please correct me if I'm wrong.

  • Hold it! As far as I know, you cannot get your messages to space "and back", because the SPOT Connect only sends data, right?

  • Actually you don't need a 4-layer board for the PCB antenna itself. With a 2-layer board you will have some trouble for matching a 50-ohm transmission line from the antenna to the module, but with a 0.8mm board you can get an acceptable trace width.

    Update: it works! I just tested the board I designed based on the PCB antenna guidelines of the datasheet. I used a 0.8mm board with FR-4 material and a 56.5 trace width for the 50-ohm transmission line. If you need more info drop me an e-mail joseluis at satelinx dot com .

  • Then change it for "Just don't tell your husband you're hacking the Roomba". Seriously guys, chill.

  • Arrrrr-duino!

  • Which u-blox module did you use?