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Low voltage coin-cell and Propeller does work — Parallax Forums

Low voltage coin-cell and Propeller does work

Jay KickliterJay Kickliter Posts: 446
edited 2010-12-17 12:43 in Propeller 1
I don't mean to double post, but I felt I should add this thread just in case someone in the future needs to run a Prop off a coin-cell. There wasn't much information available when I was researching this.

I found the the Propeller has no problem running off 2.9 V CR2032 and RCFAST internal oscillator. You can read more about it here. I haven't tested how long my circuit runs, but it seems like a reasonable amount of time for a simple demo circuit like my calling card.

There seems to be some hysteresis in the circuit. On a bench supply it seems like circuit doesn't turn on until VDD is swept up to 2.86 V, but it keeps running until it is swept down to 2.84 V. Take this data with a grain of salt, as I may be overlooking something obvious.

To reiterate, with either internal oscillator, and a CR2032 coin-cell, the Prop has no problem blinking lights and running loops. I'll add a follow up if I ever try to run it with a crystal.

Comments

  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-06 07:10
    Two nails and a lemon next :^)
  • AleAle Posts: 2,363
    edited 2010-12-06 08:55
    A lemon ?, too much waste, a potato is lower power !
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-12-06 18:40
    Potato? There's a flower that secrets an extra amount of acidity along with its nectar. Use a bunch of flowers in series for true "Petal Power." So the parts list reads something like prop, flowers, vase of water, sunlight.
  • prof_brainoprof_braino Posts: 4,313
    edited 2010-12-06 21:44
    Toby Seckshund wrote: »
    Two nails and a lemon next :^)

    That won't fit in my wallet! What about a credit card size photocell ? I mean solar panel. That way you don't use power till you take it out of your pocket?
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-12-07 00:39
    prof_braino,

    "What about a credit card size photocell?"

    ...actually if it were a credit card sized "solar cell" instead of a photocell it would be just about right.

    At roughly .077 Watts per square inch, a credit card would come in at just over 7 square inches ... 0.539 Watts

    Power = Current x Voltage

    0.539 Watts / 3.3V = 163mA ... perfect for the Propeller


    Actually to get the MPP (Maximum Power Point) right the solar cell will need to be configured at about twice the voltage, so...

    0.539 Watts / 6.6V = 81.6mA ... Still a respectable amount
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-07 03:16
    One problem with all these calculations, it would be nice to be on the Equator with a clear sky but in the UK in December ??

    But then the potato option wouldn't be much good either, the crops are frozen in the ground (and then the lemon got drowned in some G+T)
  • Heater.Heater. Posts: 21,230
    edited 2010-12-07 04:03
    Toby,
    ...the lemon got drowned in some G+T

    So what we need is a weeny alcohol powered fuel cell http://www.sciforums.com/showthread.php?t=70553

    Drop the business card into a G&T (minus the T is probably better) and it starts to do it's thing.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2010-12-07 04:55
    I've played around with the new flexible solar cells. Not quite as efficient but much easier to work with. Just glue them onto the credit card.

    The prop can go into sleep mode most of the time and you could charge up a small rechargeable battery with the solar panel, then when you want to do a demo there will be plenty of juice.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-07 05:31
    With just a little more pushing this tread will veare into my "Empty beer can powered lawn mower" thoughts.

    I do not have any Sulphuric acid for that fuel cell experiment, wouldn't vinegar be better for our chips??

    (Thankyou very much, I'm here 'till Thursday, TISH)
  • icepuckicepuck Posts: 466
    edited 2010-12-07 06:00
    How about powering it with the Baghdad battery? Now that would be cool.
    http://en.wikipedia.org/wiki/Baghdad_Battery
    -dan
  • wjsteelewjsteele Posts: 697
    edited 2010-12-07 17:23
    Heck... let's get a little simpler... include a kite, a key and some wet string. Oh yeah... it won't work very often or for very long... but I imagine it would put on one heck of a show once "prop"erly activated.

    Bill
  • prof_brainoprof_braino Posts: 4,313
    edited 2010-12-07 22:24
    Ok, This is an idea that might be synergistic with Jay's business card. Stop me if somebody has already done this.

    My daughter brought home a computer she designed for me. It was just a mock-up, she's in 3rd grade. It was shet of notebook paper folded into 16ths. On one side, each little box was the cover of a "video game" like tetris and sudoku. Unfolding it to a two box size was a cell phone, and finally the full sheet (with one fold down the middle) was a clam-shell laptop. It was really cool, I've been thinking how to build this type of from - configurable, modular device.

    Now, what about a three board affair with a solar panel, an LCD, and a keyboard? The LCD and keyboard would have to be a little bigger than a credit card maybe, but Ive seen cell phones with full keyboards that are about that small. If it was membrane keyboard, just the buttons without the keys? and a monochrome LCD instead of color? Could a solar panel charge super capacitor enough to run a prop? I realize this might be a little excessive for a business card, but hey, if you want to make an impact, this ought to do it!
  • Jay KickliterJay Kickliter Posts: 446
    edited 2010-12-17 12:43
    Turns out the Prop can work with a pretty small battery. I just ran the card with a wedged-in CR1220. I was expecting maybe 30 minutes, but got almost 6 hours.

    I'm going to revisit my old 8x8 LED matrix badge, this time redesigned with fewer parts on a shiny black PCB. Should be able to get the price to less than $15 each. You can have CGoL playing on your chest.
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