How can I build a simple radio-controlled device locator?

Thread Starter


Joined Dec 29, 2006
I want to develop a device to locate equipment within my house. This doesn't need to be anything sophisticated, like GPS or GSM. The base station just needs to be able to page the equipment, and sound a beep and/or turn on a light on the equipment. The range does not have to be very far, say, 150 to 200 feet.

Hopefully this can be done relatively inexpensively with existing technologies. I envision using garage door opener technology, but without any motors having to be activated. I think that I would have a base station plugged into a 110-volt A/C outlet, and a battery-operated speaker and light on the equipment to be located.

It would be nice if 2 or more devices could be located, separately, perhaps with different radio frequencies, from the base station. And maybe the frequency could be different for each device, maybe with single side-band or some other way to distinguish between the devices.

Eventually I would like to have the actuator become a thin piece of adhesive tape, with the receiver, speaker, light and battery built into the tape.

I would appreciate links to places which have the microchips and transmitters ready to purchase, which can be assembled as one combined unit. If that is not possible, then I would need help in designing micro circuits for the project. I have a computer background, both hardware and software, so I feel I could handle the programming, but I don't have radio or microcoding experience. So any general help you can provide would be appreciated.

This is a small project, one which I think I would have a lot of fun completing. But I just don't know where to start. Thanks for your help.


Joined Apr 20, 2004

Building such a device might be pretty hairy. There are similar items on the market for locating lost keys, though. You have a control with several buttons, and small tags that attach to the keys. Pressing the buttons results in at least a beep from the selected key tag. You could probably find one by googling something like "key locator".


Joined Dec 27, 2006
One of the biggest obsticals to your design will be battery life. I would recommend that you look into Zigby technology as they have already set a standard, and many companies are building very small devices that are exactly what you are looking for, and they are specifically designed to optimize battery life.

Some of the modules that you may want to check out are:
Freestar by LSR (
Matrix by LSR (, (this module is still in development)
XBEE by Maxstream (
Pan80215HAR by Panasonic

All these modules (except matrix) are based off the Freescale Zigby Technology, and should all be in the <$30 us / per unit in small quantities. As well they will all work out of the box as a cable replacement unit. If you want to utilize the onboard micro as part of your application, you can download the Zigby Stack (their are 3 levels) and embed your code alongside of the Zigby stack. For your application, I would reccomend the SMAC (the simplest of the 3 Stacks)

The above modules are only a fraction of what is available in the Zigby world. You could also consider other modules, ie car remotes, straight fm transmitters (ie Linx rf modules rxm-315-lc), but the problem with those methods is your battery life on the unit to be found.

If you really want to be cutting edge, (smallest, & most battery life, longest range & cheapest)
Check out the single chip solutions from:
TI (formerly Chipcon)

Although at that point, the complexity of your project will grow exponentially.