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Designing the PC Power Monitor - Part II

In Part One of this project I developed a test circuit that proved that it would all work. In Part II, I actually redesign the bread boarded prototype into the final product.

Taking the GPS for a walk in the bush

The next day I set out to map some of the roads and tracks around a patch of Bush that I have been frequenting for a few years - recording native Orchid growth etc.

Here is the voltage recordings of the battery:

11:30 13.25V (No load)

11:32 12.63V (PC On)

14:45 strong electrical burning smell noted!

14:50 9.8V (No Load)


Talking the GPS for a drive

Ok, time to go for a walk and a drive...

I checked out my last lot of GPS code from the SWASC subversion repository and uploaded it to the MARK I mini-ITX PC. I then went for a walk around the park at the back of the house. The PC and GPS where running from a common 12V 7A Sealed Lead Acid (SLA), battery. The first walk lasted 1 hour 40 minutes. I noted the voltage drop over this period:

13:40 12.28V (on load)

14:00 12.14V

14:40 11.96V

15:00 11.88V

15:05 12.00V (no load)

Trip to Perth

Arrived back from Perth late Friday afternoon, after a fun filled 3 days with Ross, doing all the holiday things.

Like visiting electronic and hobby stores as well as Battery wholesalers.  I picked up a 12V 28Ahr SLA Battery to run the Servo and Motor, and a 7AHr SLA Battery to run the electronics.  I also picked up some other batteries (7AHr and 4Hr), to repair some old UPS's.

We also found a "$6.00 All you can eat" Indian restaurant.  We ate way too much!

Building a RS-232 interface for the Digital Compass

I have purchased a 2D Honeywell 3100 Digital Compass.  This uses a TTL RS-232 voltage level, so since I need to connect it to a PC, I will need to make up a converter curcuit using a MAX232CPE chip.  I have one here, but I think it's stuffed (from a previous experiment some years ago).

I will pick up two more in Perth next time I am up there.  I will also purchase the batteries, Hall Effect Sensor and battery charger. So much to do, and so little time :-)

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