SparkFun will be closed Nov 26th and 27th for the Thanksgiving holiday. Orders placed after 2:00pm MT on the 25th will ship out Monday the 30th.


Member Since: February 5, 2007

Country: United States



Electro-mechanical Engineer


Stewart Signs

Programming Languages

VB6.0, Arduino, C++


St. Petersburg College

  • Datasheet mentions 1.6v drop on the AC side at room temperature. At 40A load, that’s 64 watt of power you need to dissipate via heat sink! The datasheet shows you the recommended heat sink for this product. I’d recommend basing your heat sink calculations on something higher - 100-150 watt so it doesn’t get so hot and can rely on convection rather than needing a fan to cool.

  • A quick and easy solution to how to plug a 26 pin (2x13) ribbon cable into the existing header without cutting anything is to get one of the beaglebone stackable connectors (PRT-12790) and cut the pins off that. Use that between the existing header and the ribbon cable. As far as which is better, BBB or RPi, it all depends on what you’re doing. Lots of video stuff, RPi excels. Need lots of IO or precision timing to talk to devices, the BBB excels in that. Want a full schematic as well as gerber files? BBB IS OSHW, RPi is proprietary and closed-source. I agree that RPi should have a power input header instead of using micro USB. And it would be great to see an increase in processing power. In my experience, playing video back at 1080p30 was a bit choppy.

  • Impressive project!
    Since the thread movement against the flat spindle somewhat replicates the motion of a sewing needle on a sewing machine, using a pre-tensioner mechanism similar to what’s used on sewing machines might reduce jamming and make the operation smoother/faster. The pre-tensioner on a sewing machine is the arm just above the needle that bobs up and down with the thread looped through the end. Also, a grayscale optical encoder on one of the steppers could quickly establish jam detection if it deviates from the expected bit pattern, and provide a way to alert that it needs “assistance”.

  • I was thinking to use three of these units. One as a base and two as remotes. Both remotes would need to connect simultaneously with the base (Data rate will be really low and intermittent, but random). Is that possible with these Bluetooth modules? Or do I have to use Zigbee?

  • I got my EasyVR shield and have gotten most of the code to work fine. I’m having trouble understanding how to initiate Speaker Dependent training through the API (Without PC connected) and can’t find any good examples and the documentation is lacking. The best I could figure out resulted in one training being stored, but it’s adding a new index in the position instead of using what’s there, the label comes up blank and I can’t seem to get it to train the second time for that command. Has anyone else figured this out?

  • In the notes it says that USB keyboard is REQUIRED in order to boot. Is there any way around this? It would be great to just add VNC and be able to remote in rather than having to tie up a keyboard..

  • You obviously haven’t dealt much with motors.
    My 1/10 carbon fiber RC car pulls upwards of 78 amps from a 7.2v NiMh pack under acceleration. That’s from a 14 turn mag motor and run of the mill ESC. He has 6 wheels and a lot of weight to push around (including the snow). I’d guess he has 6 much larger independent motors pulling a max of 110 amps each. Totally realistic!

  • The way most seismographs work is they have a pendulum with a weight near the fulcrum and the measuring device (pen) at the other end, a magnitude of the distance between the weight and the fulcrum. I would think that duplicating this type of setup would offer better signal range. You would also need to calculate how much movement to expect to see at the measurement point and size the sensor maximum G-force based on that. It would also be better to have a precision reference voltage rather than just relying on the one presented by the FTDI chip on the Arduino board. Something with high accuracy throughout the temperature range.

No public wish lists :(