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From: "Phil Allison"
Subject: Re: Detecting moment when a fast moving object passes over a line
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Sun, 24 Nov 2002 10:55:06 +1100
NNTP-Posting-Date: Sun, 24 Nov 2002 10:44:49 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Richard Sim" wrote in message
> "Phil Allison" wrote in message
> > ** Such systems as you want are commercially available - as I bet
> > are already aware. I did model electric RC car racing as a hobby for a
> > while and the topic of transponders etc was one of considerable interest
> and> > often discussed since a similar system was needed for model boat
> Yes, I know there are several commercial systems available; all of which
> cost around $3500+, which is far out of the reach of most not-for-profit
** Nonsense - every club I know of has one or shares one with another.
> > Be assurred that is is NO task for a beginner to tackle.
> Ok, perhaps I over-emphasised how much of a beginner I am at electronics.
** Did you ?
> have created the complete system already (both the transponder at less
> 1.3" sq, consisting of mostly SMT components, and the reciever/decoder),
> it does "work".. just not very reliably (due to the cars powerful motor
> magnets, and distance from the start/finish line).
> The transponder is controlled by a PIC 12F675, so it may be possible to
> differentiate between the magnetic fields with the current circuit and
> code changes on the PIC.. does anyone have any suggestions on how to go
> about doing this, and finding correct values/thresholds?
** You have explained nothing. You mention Hall effect and then RF -
how does your transponder output a signal to the receiver ? Is it a radio
frequency signal ? If so what is the frequency ? Modulation ?
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