[SATLUG] Sine of the times?

FIRESTORM_v1 firestorm.v1 at gmail.com
Fri Apr 4 13:02:58 CDT 2008

Here's a good question for you mobile computing geeks out there.

I have run into a bit of a problem with my Artigo, an 8 inch point of sale
CRT monitor and an inverter that I installed in the car.  The inverter
refuses to power the monitor, but will power the Artigo, my laptop (with no
batteries in it) and an external hard drive.  When I connect the exact same
setup to a Kill-A-Watt, I find that I when the whole setup is up, it pulls
scarcely over 50 watts at 2 Amps. The inverter is rated at 600W surge, 300W
nominal and in my testing the Kill-A-Watt only showed a spike up to 80W (a
fraction of a seccond as the monitor was turned on) When I connect the
inverter to my little 8 inch CRT monitor, the inverter shuts off.

I was talking to some of the guys at the office and I was told that because
the inverter produces a square wave and not an expected sine wave that the
monitor needs. Due to the fact that it's a CRT monitor, he said that the
transformers inside won't operate and will shut the inverter down.  Since
all the power supplies for the laptop and the Artigo are all switching power
supplies, it takes the AC and converts it to DC then performs additional
conversions to get the voltages to the required outputs.  Additionally he
said that the feedback supplied by the transformers would actually harm the
inverter! I'm already planning on doing a direct-to-battery setup with some
12ga wire but if I can't get the power issue worked out with this monitor,
I'm grounded..  (pardon the pun)

I do understand the difference between sine and square wave signalling, but
I have seen far too many people run a lot bigger TVs off of smaller
inverters with no issues.  Why is my little 8in monitor not working?  I have
already been advised to get a small LCD monitor, but the price of an 8in LCD
is almost $300 and if I am going to pay that, I might as well as buy a 20in
LCD but that defeats the purpose of the portable rig.

What do y'all recommend? What inverters do you all use out there?  Do you
think a bigger (700W) inverter would work?

(And for the linux tie in, the Artigo is also running dual boot Windows and
Linux.  It's my Dr Jekyll and Mister Hyde box.)

Any help would be appreciated, thank you.


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