SV: [basicstamps] Sonar Question
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Posts: 46,084
Greetings!
It's NOT a good idea to use a liquid...
In areas of winter frost...
Other than that, liquids don't compress, and if it's a heavy vehicle you can
get quite a lot of pressure at the end.
As for the wires used in the ground, I know that at least the traffic
counting boxes we use here in Norway uses some sort of piezo-electric effect
to register the cars.
Another method might be a coil in the ground. It'll change characteristics
when a large metal object is close.
(Ram a sinus signal through it, then nto a rectifier and measure the voltage
level.)
Just thinking out loud...
:-)
Trygve
Opprinnelig melding
Fra: Pat M [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=rssJJN0nS7AzoPiUTiLFb9ZfzmPmPyn_faRWQeH-Cwz1trHEfUvtdYT0PDXrvSgfnrnjCgixLCha]pmeloy@s...[/url
Sendt: 13. januar 2003 16:02
Til: basicstamps@yahoogroups.com
Emne: Re: [noparse][[/noparse]basicstamps] Sonar Question
Real traffic lights use a wire loop to detect large metal objects. Dont
remember the details but it was a pretty simple thing.
The other possibility is a pressure activated switch and inflated tube. You
could use a garden hose with water in it, cap one end and stick some sort of
rubber membrane over the other. Car hits the hose and the rubber baloons
out, pushing a microswitch. Run a wire from the stamp pin to the switch then
from the switch to ground and pull it high. Make the switch, the input goes
low and your stamp does its thing.
Original Message
From: <verhap@o...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 6:20 AM
Subject: [noparse][[/noparse]basicstamps] Sonar Question
> I've been asked to build a traffic light controller for a teacher's home
> (it's not a real traffic light, but must act like one). He'd like the
> traffic light to operate once a car pulls up into his drive way. The
> lights are 120 Vac, so I plan to use the Opto 22 as the relay for the
> BS2 and to bash a 12V lighting system for power. However, first I
> need to detect the presence of a car. I was thinking about using
> the same sonar used in robots. Has anyone tried one of them
> outside in the real world's noise? I'm concerned about false
> detections.
>
> Thanks,
> Paul
>
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It's NOT a good idea to use a liquid...
In areas of winter frost...
Other than that, liquids don't compress, and if it's a heavy vehicle you can
get quite a lot of pressure at the end.
As for the wires used in the ground, I know that at least the traffic
counting boxes we use here in Norway uses some sort of piezo-electric effect
to register the cars.
Another method might be a coil in the ground. It'll change characteristics
when a large metal object is close.
(Ram a sinus signal through it, then nto a rectifier and measure the voltage
level.)
Just thinking out loud...
:-)
Trygve
Opprinnelig melding
Fra: Pat M [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=rssJJN0nS7AzoPiUTiLFb9ZfzmPmPyn_faRWQeH-Cwz1trHEfUvtdYT0PDXrvSgfnrnjCgixLCha]pmeloy@s...[/url
Sendt: 13. januar 2003 16:02
Til: basicstamps@yahoogroups.com
Emne: Re: [noparse][[/noparse]basicstamps] Sonar Question
Real traffic lights use a wire loop to detect large metal objects. Dont
remember the details but it was a pretty simple thing.
The other possibility is a pressure activated switch and inflated tube. You
could use a garden hose with water in it, cap one end and stick some sort of
rubber membrane over the other. Car hits the hose and the rubber baloons
out, pushing a microswitch. Run a wire from the stamp pin to the switch then
from the switch to ground and pull it high. Make the switch, the input goes
low and your stamp does its thing.
Original Message
From: <verhap@o...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 6:20 AM
Subject: [noparse][[/noparse]basicstamps] Sonar Question
> I've been asked to build a traffic light controller for a teacher's home
> (it's not a real traffic light, but must act like one). He'd like the
> traffic light to operate once a car pulls up into his drive way. The
> lights are 120 Vac, so I plan to use the Opto 22 as the relay for the
> BS2 and to bash a 12V lighting system for power. However, first I
> need to detect the presence of a car. I was thinking about using
> the same sonar used in robots. Has anyone tried one of them
> outside in the real world's noise? I'm concerned about false
> detections.
>
> Thanks,
> Paul
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
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Comments
> when a large metal object is close.
> (Ram a sinus signal through it, then nto a rectifier and measure the voltage
> level.)
The problem is the teacher will not want to tear up his drive way for
this. But it does sound like the ideal solution (which is why I
suppose cities use it).
Paul
You don't nessisarily have to 'tear up' the driveway to do this.
You could simply take a asphalt cutting saw blade in a demolition saw (a
tool rental sho will know what this is) and cut a octaganal grove into the
driveway with a lead in grove to one side. Once you lay in the wire you can
seal it into the grove with common asphalt crack filler from a home center
(Home Depot etc).
If you look at the pavement the next time you're at a stoplight you'll see
what I mean.
Have a good day,
Kevin Lavigne
Original Message
From: <verhap@o...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 13, 2003 10:17 AM
Subject: Re: SV: [noparse][[/noparse]basicstamps] Sonar Question
> > Another method might be a coil in the ground. It'll change
characteristics
> > when a large metal object is close.
> > (Ram a sinus signal through it, then nto a rectifier and measure the
voltage
> > level.)
>
> The problem is the teacher will not want to tear up his drive way for
> this. But it does sound like the ideal solution (which is why I
> suppose cities use it).
>
> Paul
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>