January 2001, Issue 126

Where's Waldo?
Pinpointing Location by Interfacing with a GPS Receiver

WRAP IT UP, I'LL TAKE IT!

My first thought was to include a couple of regulators with logic inputs, U2 and U3, as in Figure 3. To reduce current draw, I would turn off the devices until they were needed. At an operating current of less than half an amp, I’m not going to worry about it.

All this fits into a box about the size of a brick (see Photo 3). Most new vehicles come with an alarm system. You can take an alarm output and connect it to trigger the AutoLocator. Or, mount a simple toggle switch somewhere under your dash and power the AutoLocator from this switch through the accessory circuit that’s powered when the key is turned on. If anyone tries to steal your car without turning off the secret switch, the AutoLocator goes into action.

Photo 3—The project fits into a small enclosure that can be hidden in your trunk. But, the magnetic GPS antenna works best where it has a full view of the sky.

You will need to keep your computer in host mode to answer the AutoLocator’s calls. Now, I bet you can think of a quite a few other great ways to use this project. There’s another feature I want to add, but that’s all I’ll say about it for now. Care to venture a guess?

Jeff Bachiochi (pronounced BAH-key-AH-key) is an electrical engineer on Circuit Cellar’s engineering staff. His background includes product design and manufacturing. He may be reached at jeff.bachiochi@circuitcellar.com.