Let's Make Robots!

while waiting for some parts

while waiting for some parts, I've got some little sensor that I'm trying to figure out how it works.

 It's part of the bigger project. the sensor is part of the waypoint navigation system that I'm working on.

It's a small toy transmitter(3 came with the kit each on different channels) that senses motion. Now from looking at the sensor(input), it looks like an led which made me think it might be an ir sensor. I'm not absolutly sure how it works though. It detects motion or some object passing in front, but it uses the outside light as a reference light, at least I'm assuming thats what it's doing. This made me think it's some sort of PIR sensor. When I had it near my desk, I had a fan cieling going and that appeared to have been triggering it as it was sending a signal to the base(receiver) unit setting it off. This also made me think it might have been PIR. When I checked the voltage on the sensor with no motion, it showed 2.6 volts(3 v power supply). when I covered the sensor input it showed the same voltage.

When I moved my hand in front of the sensor, it jumped up to three, then dropped down to 2.6 again. I also tried an ir remote(tv)  to see if it picked up the signal which it did. This time though, it dropped down to 1v instead of going up. This would seem to be similar to the action of an IR receiver(active low). But I'm wondering, is this also how a pir sensor would work.....I'm imagining so.....

I'm going to try to trace the circuit board as it's pretty compact buthas quite a few components(surfacemount) that go all over the place. The other annoying thing is that the main logic unit(whatever it is) is covered by some black epoxy like stuff. I've seen a lot of companies do this so no surprise in trying to keep their design secrets.

 Anyway, my idea is to remove the sensor, and have the high/low signal be controlled via a 08m. It would also be controlling an ir array that would be strobbed at 38khz emiting a signal designating which sensor it is( as well as location reference). The beacon would also have some ir receivers attached as to do some rudementry communication with whatever bot was near.  In turn, the beacon would send a sig to the base station that would be linked to a computer letting me know at what location the (sentry) bot is at.

The electronics are from the wild planet spy tracking system. Pretty nifty stuff if you ask me too.... 


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Pictures, pictures :)

I'll add some this weekend showing the electronics and some closeups of the sensor.

This is what the kit is though.  http://www.spygear.net/spy-gear/spy-toys/wireless_tracker 

All three sensors transmit a signal on independent frequencies. If I can modify them as I stated in my above post, they have the potential to be quite interesting devices.


The black epoxy stuff is not hiding anything. the black epoxy stuff is the main logic unit. it is their propritary mass produced IC.. its not a standard component. they But a Glob of that crap over the silicon when they make  the PCB's. have fun with that.


I knew it was the main unit, just never sure why they had it covered other than to possibly try to hide the chip...but intersting fact to know...

I was able to trace the wire and do some tests,with the board by removing the sensor and triggering the input that would send the signal.  I created a rough schematic of the layout I want to use for testing the 08m with it, which just includes a single ir emmiter, detector and a charge pump(to increase voltage) for the emmiter. Considering I want to use around 4 emitiers to get close to 360 coverage, I may need an external battery unit for this to work as the chargepump has a limited current capacity that would limit it's use to just one emmiter, 2 if I wanted to push it with a weak signal .I'll have to test the coverage with 3 to see if that would help in reducing the power consumption. 

Now is the time I wish I had tools to work with surfacemount tech....  :/