Tuesday, October 17, 2006
Metal Detection - Prototype 3
1. After our failed attempt at the makeshift metal detector, we decided to order a kit. The kit consisted of a search coil connected to a small, simple processing board with the reference coil attached as well as a LED indicator light. There was also an attachment for a "buzzer" which we decided not to use. Instead, we connected the positive and negative output wires to our flexinol actuator directly.
Results: When the flexinol was connected, nothing in the system operated. Weird.
2. We then connected the positive and negative lead wires to our micro controller in place of the PIR sensor (and the flexinol actuator connected again to the micro controller).
Results: The system responds (we know this because of the LED indicator), however, the LED is weakened in brightness and the flexinol does not respond. We think we need to amplify the output voltage somehow. (The processing board from the kit has too many resistors.) ]
3. The last test was to directly connect another LED in place of the microcontroller or flexinol. (This is what is pictured above.)
Results: The additional LED worked just the same as the LED on the processing board.
If anyone is interested, here's info on how metal detectors work and how to build them:
This site has some other interesting "build it yourself" projects which might be helpful to other teams: