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I'd like to try to make a mobile device like this that can run with ~100mA input power from a solar cell. I thought about using the Particle Photon & an E-ink d

I'd like to try to make a mobile device like this that can run with ~100mA input power from a solar cell. I thought about using the Particle Photon & an E-ink display, but my knowledge of hardware isn't the greatest. Any EE out there think it's possible?

quickben 9y ago
It would be a bit of a learning curve, but certainly doable. Especially if you find a schematics that you want to assemble and try to follow the instructions and assembly. It can be like a giant puzzle with too many rules. But doable. If not on the first try, then on the subsequent ones :)
duskwuff 9y ago
How large of a device do you have in mind? 100 mA is more than enough power for the Photon module, but would require a relatively large solar cell -- probably at least 3 to 4 inches square under ideal conditions.
- grizzles 9y ago
  That's roughly the size I was thinking. I was thinking of adding a battery too, less as a storage bank and more as a way of papering over the ideal conditions issue.
  - KGIII 9y ago
    Have those graphene supercapacitors become commercially available? If so, you may be able to do without a battery at all. Well, depending on use, available charge, and efficiency.
boznz 9y ago
There are a few already out there (https://hackaday.com/?s=cell+phone https://hackaday.com/?s=cell+phone) for proper open source mobile comms, the real problem is the mobile spectrum, I had a similar whinge on my blog a few weeks ago http://rodyne.com/?p=832 http://rodyne.com/?p=832.
Dylan16807 9y ago
If your budget is 100mA at 3-5v you can use normal phone hardware locked to low frequency and brightness.
- carlesfe 9y ago
  My SIM800 and SIM900 draw 2A on bootup, and 500-1000mA when calling. Do you know any off the self components which can fully operate on 100mA?
  - Dylan16807 9y ago
    That's mostly radio power, right? To compare to the system in the article, we don't need to have our signals reach normal towers. We only need to reach a femtocell, and those can be as low-power as 10mW. For example a quick search found the ADF4602, a 3G transceiver that runs fine at 50mA. And that's transmit/receive power; a good 3G+ receiver can go idle between packets.
deleted 9y ago
[deleted]
retSava 9y ago
Such a solar panel is quite large/powerful and you can drive quite a lot on that, depending on how and where you deploy it. One of the most important factors on how to make it live longer is to limit the steady-state static draw (ie ensure you go to sleep modes properly etc). Plug, but _just now_ our related post got to the first page: https://news.ycombinator.com/item?id=15354741 https://news.ycombinator.com/item?id=15354741
- jcun4128 9y ago
  Can you expand on that "limit the steady-state static draw" Don't you need to keep draining power produced by solar panels? What about the heat problem and decreasing efficiency of solar panels?
  - retSava 9y ago
    The steady-state static draw is the current consumption that is always there even if nothing is going on. Everything else that happens is added on top of it, so to speak. When the microcontroller is at sleep it will consume a certain amount to current to eg keep registers and RAM intact (otherwise it would become corrupt). It is also due to leakage currents from capacitors, and any leakage that might go out through GPIOs. Sensors also have a static draw when not in use. Batteries self-discharge. And so on. For example, a cc1310 system on chip has a 0.8uA current consumption when in deep sleep, but the real static draw is more than that. Periodically, the chip will run a little charge pump to energize RAM so that it doesn't evaporate (metaphor). There might also be a timer active, and that consumes 100uA. And so on. When the device wakes up to run at 24 MHz, it uses about 1.9mA, plus any peripherals (SPI 13+93uA, timer 113uA), plus any sensors or other hw peripherals. This might be very very short amount of time, like 10 ms every two hours-kind of short. So it turns out, that for a device that wakes very rarely, the static draw can be a significantly decrease lifetime. It's small, but it is _always_ there. It is hardware-dependent and is the "black art" within embedded development. It's very easy to reach arduino-levels, pretty easy to start using low-power modes, time/money-consuming and requires expertise to squeeze the last years/months out of the battery.
    - 9y ago

quickben 9y ago

It would be a bit of a learning curve, but certainly doable. Especially if you find a schematics that you want to assemble and try to follow the instructions and assembly. It can be like a giant puzzle with too many rules. But doable. If not on the first try, then on the subsequent ones :)

duskwuff 9y ago

How large of a device do you have in mind? 100 mA is more than enough power for the Photon module, but would require a relatively large solar cell -- probably at least 3 to 4 inches square under ideal conditions.

grizzles 9y ago
That's roughly the size I was thinking. I was thinking of adding a battery too, less as a storage bank and more as a way of papering over the ideal conditions issue.
- KGIII 9y ago
  Have those graphene supercapacitors become commercially available? If so, you may be able to do without a battery at all. Well, depending on use, available charge, and efficiency.

boznz 9y ago

There are a few already out there (https://hackaday.com/?s=cell+phone https://hackaday.com/?s=cell+phone) for proper open source mobile comms, the real problem is the mobile spectrum, I had a similar whinge on my blog a few weeks ago http://rodyne.com/?p=832 http://rodyne.com/?p=832.

Dylan16807 9y ago

If your budget is 100mA at 3-5v you can use normal phone hardware locked to low frequency and brightness.

carlesfe 9y ago
My SIM800 and SIM900 draw 2A on bootup, and 500-1000mA when calling. Do you know any off the self components which can fully operate on 100mA?
- Dylan16807 9y ago
  That's mostly radio power, right? To compare to the system in the article, we don't need to have our signals reach normal towers. We only need to reach a femtocell, and those can be as low-power as 10mW. For example a quick search found the ADF4602, a 3G transceiver that runs fine at 50mA. And that's transmit/receive power; a good 3G+ receiver can go idle between packets.

deleted 9y ago

[deleted]

retSava 9y ago

Such a solar panel is quite large/powerful and you can drive quite a lot on that, depending on how and where you deploy it. One of the most important factors on how to make it live longer is to limit the steady-state static draw (ie ensure you go to sleep modes properly etc). Plug, but _just now_ our related post got to the first page: https://news.ycombinator.com/item?id=15354741 https://news.ycombinator.com/item?id=15354741

jcun4128 9y ago
Can you expand on that "limit the steady-state static draw" Don't you need to keep draining power produced by solar panels? What about the heat problem and decreasing efficiency of solar panels?
- retSava 9y ago
  The steady-state static draw is the current consumption that is always there even if nothing is going on. Everything else that happens is added on top of it, so to speak. When the microcontroller is at sleep it will consume a certain amount to current to eg keep registers and RAM intact (otherwise it would become corrupt). It is also due to leakage currents from capacitors, and any leakage that might go out through GPIOs. Sensors also have a static draw when not in use. Batteries self-discharge. And so on. For example, a cc1310 system on chip has a 0.8uA current consumption when in deep sleep, but the real static draw is more than that. Periodically, the chip will run a little charge pump to energize RAM so that it doesn't evaporate (metaphor). There might also be a timer active, and that consumes 100uA. And so on. When the device wakes up to run at 24 MHz, it uses about 1.9mA, plus any peripherals (SPI 13+93uA, timer 113uA), plus any sensors or other hw peripherals. This might be very very short amount of time, like 10 ms every two hours-kind of short. So it turns out, that for a device that wakes very rarely, the static draw can be a significantly decrease lifetime. It's small, but it is _always_ there. It is hardware-dependent and is the "black art" within embedded development. It's very easy to reach arduino-levels, pretty easy to start using low-power modes, time/money-consuming and requires expertise to squeeze the last years/months out of the battery.
  - 9y ago