critter ridder for vehicle app

[MrDEB]

Back to my critter ridder (wildlife avoidance system that I designed).
Back to the grind as most of my other small projects are done now.
Need a way to detect vehicle speed. Thinking of a potemeter with a flapper that is mounted inside a pipe.
The flapper rotates a given amount according to the wind speed inside the pipe. Reading the resistance (ADC) connected to PIC. X amount of resistance = X speed. The trigger or ON trigger can be adjusted with a trim pot.
The flapper moves say 1/4inch then the resistance is X
BUT is there a pot that has a very low toqure rating (amount of torque to turn shaft?
thinking very little but the flapper can be weighted or enlarged for lees or more resistance.
A rotary encoder might work but??

 

[phoenox]

You could use a phototransistor and an LED. Set it up so the flapper itself breaks the beam. Then the flapper will not have to be driving any mechanical load.

 

[MrDEB]

I thought about that but the photo transistor could get dirty but may have to refigure system setup.
also have a speaker that shouldn't get wet as well

 

[Diver300]

Do you want vehicle speed or wind speed?

Anything that uses a flap etc would be really non-linear, and difficult to set up

I would suggest one of the following:-

Read the CANBUS of the vehicle.
Use a GPS receiver
Magnetic or optical pick up from the ABS sensors or the speedo cable
Magnetic or optical pick up from a free-running propeller if you really want wind speed.

Any of those is going to be far easier to get working.

 

[MrDEB]

I want it to be able to be installed on any vehicle, even a motorcycle if possible.
My thoughts are to measure the wind speed or pressure as the vehicle travels down the road. If the flap rotates say 20 degrees from vertical ( down position with vehicle at stand still) then read the resistance of the potentiometer then using ADC compute the desired speed to turn the device on.
so many different combos on today's cars that actually connecting to anything other than the battery would perhaps run into problems.
perhaps a wheel that rotates in the wind. measure the rpm then compute vehicle speed.

 

[dougy83]

perhaps a wheel that rotates in the wind. measure the rpm then compute vehicle speed.

Sounds like a [fan] anemometer. There's also the option of a hot-wire anemometer.

Anemometer - Wikipedia, the free encyclopedia

 

[Sceadwian]

Why use such a complicated system? Just get those whistlers that attach to intake grills. They're totally passive require no electricity and all you have to do is check them every now and then to make sure a bug didn't get lodged in them.

 

[MrDEB]

its a proven fact that them deer whistlers don't work. they are in the ultrasonic range. somewhere I have a study done by a university that found that deer etc. respond better to sound in the 2 - 8 khz range. or is it 2 - hz??
my PIC randomly cycles between the desired range. did some testing and the local deer population here in Salmon do not like my device.
And yes I left it home while hunting this year. Just wish I could hunt in town as I have about 6 deer that come in my yard almost every night. a nice 3 point (6 points total) is among them but I perfer the does. much better eating. had some back strap last week. best meat I ever tasted.
don't waste you money on them whistlers.

 

[Sceadwian]

You put the whistlers on a car, not in your yard.... They're ultrasonic... They're also VERY loud at speed.

 

[MrDEB]

My unit is being designed for both apps.