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Subject: Re: Car counter / DETECTOR

Date: 07/05/00 at 2:23 AM
Posted by: Jeff Jones
E-mail: jeff_sr@yahoo.com
Message Posted:

In Reply to: Re: Car counter posted by Jim Drew on 05/30/00 at 6:41 PM:

Hi Vorel, I've been reading your posts on CAR Counter.
I have a need to detect vehicles driving down driveways at 1 to 20 mph.
I think I need a ferrite rod with maybe 200 turns of 30 ga. enamel wire. I really
don't know what the physical dimensions of the rod should be, the frequency range
of the ferrite, or the length of the wire. I do think I want to amplify the coils output
then pass it to a LM339 for a window comparator. I imagine the waveform of the
coil will change depending if the car is coming from the east verses the west. Or
north v. south. I hear that commercial units have a pot sensitivity adjustment. I think
a sample/hold switch should eliminate any adjustments. I do not want to radiate
any signal because I must operate on low current batteries. What's your thoughts?
Thanks, jeff_sr@yahoo.com

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