So, as the season started we started rooting through our control system stuff that we haven’t used since Nov/Dec. Unfortunately, one of the things we couldn’t find is the power supply for our Classmate. After looking around for a bit, we still couldn’t find it and unfortunately we had to leave for the day.
Later at home I was rooting through my IBM power supplies (I have more than I expected) and found one rated at 19V, 2.4A. The Classmate is rated at 20V, 2.0A. These numbers are obviously similar but I’m still a little nervous using them together - I don’t want to damage the Classmate. Can anyone tell me what exactly these numbers mean (I already know what volts and amps are, but I don’t know how exactly they apply to this power supplies) and if it’s okay to use this power supply?
You need 20 volts at 2 Amps, and your supply can deliver almost 20 volts (19 to be exact) at more than 2 Amps (2.4 to be exact).
So while your voltage (kind of like water pressure) is a little bit low, the current (think liters per minute) is sufficient. Extra amps are OK, since the device will use only as many Amps as it needs. The extra capacity of the supply just makes it work a little less hard (which is good).
I will not say it is OK to use this supply, but it probably won’t cause any harm. What you have to ask is, what’s the risk as compared to the reward?
Word of caution, and I may be a little paranoid here, but make sure the polarity of the substitute power supply matches that of the missing classmate supply. Off the top of my head I don’t recall what the classmates is, but you should be able to see on the casing of the IBM what it is, or worst case take a DMM to it and check.
Just the other day I forgot to check this and put reverse power in to my USB/Serial Port hub and blew the power regulator in to two pieces. Oops. (This is why I own a soldering iron though…)
I was stuck the exact predicament and can say that it worked fine, and no harm was done.
Left the classmate charger in the shop, and found a portable dvd player charger around the house (19v, 2.4A), and was able to work away at home.
Excellent, I’m glad this worked out. I was just concerned about the polarity because it could be very bad for the classmate is connected to reverse power. I’m not sure it has reverse power protection built in.
