Topic: Max voltage for infocast 8 power supply.

I made a terrible mistake and plugged a 7.2 volt power supply into my Infocast 8.  The thing is, it started up and ran about 2 hours.  And when I realized my mistake and unplugged it, it still booted up with the regular 5v power supply. Can the infocast 8 take more than 5 volts normally, or was I just really lucky?

2 (edited by Joan Jett 2012-07-13 16:43:12)

Re: Max voltage for infocast 8 power supply.

Well here is an unscientific opinion, for a while I was using one of these when I left my OEM power supply in a motel:

http://tinyurl.com/7xdzcjs

I ran a chumby classic on 4.5 volts and 6 volts, without issue. After a few days I received a replacement that I ordered and never tried it again. I'd say to be safe, it'd be better to stick with 5 volts. Sorry couldn't be more help

BTW, could I interest you an opportunity to tutor me a bit with regard to OE on the infocast 8?

Brian, #1 Joan Jett Fan

Re: Max voltage for infocast 8 power supply.

Sure, I can help out with OE for the Infocast 8, but while I got a kernel up and running, I was not very happy with it.  The Software that comes with the stock model is, IMHO, easier to deal with.  The guy to talk to is GuyC, but he's been abducted by Aliens or something.

But, since I love Rock and Roll, I'll be happy to offer advice.

Re: Max voltage for infocast 8 power supply.

These things probably have decent voltage regulation that can handle a little more.  If they use linear voltage regulators, it was probably hotter than it should have been, but if it still works it's probably fine.  If it was switched mode, if it didn't blow, it too is probably fine.

Linux Guy - Occasional Chumby Hacker

Re: Max voltage for infocast 8 power supply.

I noticed in the schematics that there is a zener diode voltage regulator circuit.  I didn't see any values, but I guess it's there for the idiots who plug in the wrong voltage, whoever they are.

Re: Max voltage for infocast 8 power supply.

Your device is very likely OK. It can take a fairly wide range of voltages - but don't push it.

Re: Max voltage for infocast 8 power supply.

The zener will help prevent against overvoltage (especially in relatively small amounts, such as 2.2V) but no, it's generally not a good idea to run it with a higher voltage than it's designed for.  Pretty much any regulator circuit dissipates extra power as heat... so relying on the regulator is probably not the best plan.

The Chumby Classic was designed to "[run] off 1A at anywhere between 6.5 VDC and 14.5 VDC"; conversely, the C1 "requires +5V, 2A DC power, regulated to better than +/-5%".  Since the C8 seems to be more like the C1 in terms of hardware evolution I'd say it is indeed designed for 5V ± about 0.25V.  Again, it's probably got some degree of built-in overvoltage protection, but your main saving grace is probably that it only ran on that for ~2 hours and so heat probably hadn't toasted things yet.  If your air conditioning is set to a cooler temperature that will only help the heat dissipation smile

TL;DR: Chumbies/Infocasts (other than CC) are not designed for excessive voltage but have some built-in protection that probably saved your bacon for the two hours it was running on the higher voltage.  Not an experiment I would recommend recreating.

Re: Max voltage for infocast 8 power supply.

mwalimu wrote:

Sure, I can help out with OE for the Infocast 8, but while I got a kernel up and running, I was not very happy with it.  The Software that comes with the stock model is, IMHO, easier to deal with.  The guy to talk to is GuyC, but he's been abducted by Aliens or something.

But, since I love Rock and Roll, I'll be happy to offer advice.

Ok, thanks very much. When you get a chance, look here:

http://forum.chumby.com/viewtopic.php?id=8235

Cheers, Brian

Brian, #1 Joan Jett Fan