would this work for measuring speed?

[jeff262]

ok i had this idea but not sure if it would work but it would be cheap if it did. i noticed that radio shack sells the small IR senders for $2 so i you put 2 on the ground like at the end of the runway and at the beginning of the runway then place a IR receiver on your plane and program a ic to measures the time when it crossed between the signal and have ic flash a led in seconds, IE the led flashs 5 times for 5 seconds it took to go from signal to signal and if you know your distance you would be able to get a accurate speed. i'm sure there are many proplem with this but just thought i would ask. just looking for a cheaper way then buying a radar gun
jeff

[pic man]

in short yes it works,

led blinking the results,,,, might as well have it in moris code or chinese, better off to install a double digit display, using one decimal point as a 100's place, pic 16f84 is capable if you run some sorta matrix on the leds, reletively simple, use a short 4 - 8 inch tube on sender and reciever, ambient light will effect these, its a rather large undertaking if your asking if its posible, gotta learn pic therory, a chip, a programing launguage, buy a compiler, programer, chips suplies , build proto type , but yes its quite posible and with the proper basic knowledge,,,,, its rather simple, ive contemplate building one my self many times, im just waiting to acumulate more junk i can work in b4 i do

[lazy-b]

guys, been thinking the same thing, but I plan to use it on a Car, Instead of putting a IR-receiver on a plane, I put a IR-Sender on a RC car might put it on a roof and send the IR beam up ward, on the ground have a over-head IR-receiver sensor.....Each Car have a different code or modulating frequency say 60 Hz,70 Hz,80 Hz....etc, as the Car pass thru the over-head IR-Receiver Will just detect which Car passed thru by detecting its modulating frequency.......I guess this is not a problem for single, I just do not know what will happend if 2 or more car passed thru simulanously......been thinking of putting more IR-Receiver say every 6 inches this might solve the problem.

If the above can not solve the simultanously car detection, I think we can put the IR-Receiver on the Car and put the IR-Sender in the over-head, but this need Individual PIC controller on a car, and have to initialize before every races and have to download all those Individual Data from the Car after every race.

I guess this is also applicable on the Pylon Racing for Plane.

I guess this is Do-able.

Ellion

[pic man]

back at radioactive raceways, they used a lil setup which used a very quiteradio freq broadcasted our of a tiny wire layed across the track, and lil reciever boxes in the cars, , actuially come to think of it reason stands to tell me that the reciever was on the track side and tx was in each car, thats how THEY did multiple cars, my original design only dictated 1 car ata time, 2 lanes, to alow for drag races,

i really dont think the top of car method would work, as these lil emiters ARE effected by ambient light, the only way me and the two guys who brainstormed this idea came down making it work, was horizontal emiter / collector, with 3- 7 inch black plastiic tube on the led to seprate it from ambient light, we decided it was not worth building vertical, due to our combined experiance telling us it wouldnt be acurate,

one way that would work,,,, look up schmetacs for a 555 ic timer ir remote controll,
this will give you plans to "encode" the pulse sent, alowing you to make a system for multiple cars, on the track side ,,, you will have either a few collectros, or circutry for all different tx systems, this could work, but unfortunatly , you have to know how many cars max whnen u build it, i sopose the resistors that differenciate the "channle" could be made to plug into a jack, as to make them changeable,

ie if you sell these systems, and at a track races are 10 peps big,, the rx is wired for 10 "channles" or resistivitiesthe car end of things, rather then switch tx's ,,, just put a corosponding resistor into the jack,

botom line, one car is a beginers project,,, 2 is intermediate, multiple is dificult ,

any other ideas from you more seasoned guys n gals, im interusted to be learned ;)