I Dream of JNE

Member Since: September 10, 2011

Country: United States


Check out what you can do with a Beaglebone and other open-source project ideas at http://knek-tek.me

  • The 555 timer can be used for a boost converter to take the 5V from a USB port and boost it up to 400V-600V! What’s this useful for? Well, you could power a Geiger-Muller tube and detect radioactive hits. And maybe use that signal to pulse some Christmas lights on and off, visualizing the heartbeat of the cosmos as cosmic rays hit your Christmas tree: http://knek-tek.me/index.php/2018/01/09/radiation-controlled-christmas-lights/

  • Will Sparkfun please do a run-down of these many, many IoT dev board options and clarify what the intended use-cases look like for each, and how they are all distinguished? There’s this product, various raspi options, the gadgets that Intel made like the Edison (before Intel withdrew from the maker market), the Teensy boards, and on and on with dozens of shields for each of those.

    So many options for an IoT dev platform! What are they for! What niche does this product fill that wasn’t already filled by all the other extremely similar gizmos?

  • If the cap only has a 2.7V rating then you would need two in series to use with a 3-3.2V bus.

  • Seconding this. The storage space and dynamic memory need to be listed in the specs.

  • Section 6-4 of the datasheet says that with no display update, it draws 6uW, so that implies that unlike a non-hybrid e-paper display this thing can NOT keep the image after losing power. So not good for a very low-power system. :-(

  • I tried reconditioning mine again in an actual humidity chamber and it worked. I must not have had the right conditions before.

  • Unfortunately after spending nearly two years in storage, my sensor no longer works, even after placing it in a very humid container for a day. It is stuck in Diagnostic mode and only gives RH=99.94%, Temp=124.98, no matter what. :-(

    Is it possible that one of these cannot be reconditioned and I have to throw it out? Your guide says >50% RH for 5 hours, which I did.

  • In the figure where you show the capacitors hanging off the Vin pin, and you had to use a diode to prevent backflow into the solar panel, you could instead put the capacitors coming off the Vcc pin (Vout on the actual chip) and like Fig 11 on p. 16 of the 3588’s datasheet you would NOT need a diode. The LTC3588-1 is able to have huge capacitance on its output without the need for a blocking diode…apparently. Haven’t tried it myself.

    Am I wrong?

  • The self discharge at room temperature seems to be pretty bad from what I just measured. I had two in series with 2.08V on them, and they proceeded to lose about 1mV/s. This is when they weren’t hooked to anything- I even removed the multimeter probes for a while to make sure those weren’t draining current.

    I’m not very happy with that since I have another 1F supercap that is pretty good at holding a charge, it’s a PowerStor Aerogel PB Series, and only loses about 50mV per hour. I bought these Sparkfun ones to power a solar powered device over night so they’re not going to work, and I need to buy some better ones off digikey. :-(

    I did some calculations to compare these to the PowerStor one, and losing 1mV off a 1F capacitor is 500nJ of energy lost. But losing 1mV off a 5F capacitor is 2.5uJ, 5x more energy lost, which makes sense. Equation is E=(½)C(V2)

    EDIT: I tested this again later in the day and now they seem to be holding charge much better, even using the same multimeter and everything. Weird, maybe they just needed to be “broken in”? Or maybe the charge loss at higher voltages is much higher than at lower voltages?

  • I used this thing and the LTC3588 buck converter (also sold on Sparkfun in a different form than what I used) to make a solar-powered web server

    The example code that is available in the Arduino library is fantastic, and the intergration with Phant.io is pretty easy too.

No public wish lists :(