Hi all, Was away from email for the past two days and could not respond, First thanks for all your suggestions. I guess I should have provided some more information, this is a personal project and I was hoping to venture into new territory as a learning experience :-). basically I am trying to develop a rollerblade speedometer. There are commercial ones available http://www.skates.com/Skate_Speedometer_p/mcrsprt8082.htm but I figured it would be interesting to build one that would combine the speedometer with Heart rate measurements etc. Anyways you can see why wireless would be the best option here (IMHO), with an optical solution not only do you have alignment issues but you also need to worry about what happens when the user rollerblades through a pool of muddy water and the led get's splashed etc. Richard Prosser & Robert B- Like you suggested a simple RF Osc might be the best option. Any circuits that you might like to share? Anyways, I was toyin around with maybe a simple CW type transmitter (maybe just a 1 trans oscillator) triggered by a hall sensor, but I like Peter Peres idea about capacitive modulation. This would really simplify the sesor and then all the computing can be done at the wrist. (Can anything say geek better that a 3" computer on your wrist) Phil & Olin - I see where you are coming from I could just add another micro at the wheel and transmit info ( I need a micro at the recieve end also to keep track of dist travelled, average mph etc) but I was hoping for a minimalist solution, although I realize that the time I spend getting it to work would probably cost me more. Thanks again for all your suggestions, I guess it's time to start experimenting! -----Original Message----- From: "Jay Shroff" To: piclist@mit.edu Date: Mon, 06 Dec 2004 20:58:23 -0500 Subject: Re: Re: [EE] Wireless hall sensor ideas Yeah, I can't do an optical sensor because the unit would have some lateral movement also and it would be hard to ensure that emitter would stay within the field of view of the detector, unless I go in for a really wide angled led. -----Original Message----- From: Richard.Prosser@powerware.com To: "Microcontroller discussion list - Public." Date: Tue, 7 Dec 2004 14:06:17 +1300 Subject: Re: [EE] Wireless hall sensor ideas I guess doing it optically is out for some reason - I would have though over that range that a flashing (& modulated?) LED would be straightforward. You may not even need the hall sensor if you have something to reflect off. RP _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist