Digital Speedometer

[mahesh_jo]

Is any body have any idea about digital speedometer. I am not an electronics engineer but its my hobby. I am computer programmer and know assembly and other things. Can we attach a magnet to motorcycle's spoke and a coil neat it so that every time the wheel passes the coil it generates some current. By measuring the dia of wheel and counting the current per second we can generate the speed of motorbike which can be displayed on a digital display.

-Mahesh Joshi

 

[Klaus]

Its done that way with bicycle speedo's. You must have a small distance (a few mm) between the tiny magnet and the sensing hall device. That is easy enough on bicycle wheels & forks but may be tricky on motorbikes with their 'interesting' suspensions. The magnet has to stick very well to survive high speeds.
Klaus

 

[mahesh_jo]

Klaus' reply

Ok the magnet may not survive the high speed of motorbikes. Can we convert the value of conventional analog speedo to digital form. I dont know the internal functioning of analog speedo.

-Mahesh Joshi

 

[Axe_Murderer]

Most traditional analog speedos use no electronics at all.

 

[tansis]

Mounting a magnet on the wheel rim can be done but is not advisable,
for one thing you must get the wheel re-balanced profesionaly.I have seen it done on a couple of custom builds before but it has never looked good.
I would suggest using an optical shaft sensor on the end of the existing speedo drive cable.But if you plan to elimiate the speedo cable....
If the motorcycle is fitted with a drum style brake you might get away with mounting the sensor in there, or fix your magnet to the section of the disc brake nearest the axle , less stress due to reduced angular acceleration ,and dont forget the balance issue,you might need more than one identical mass magnet, and have the sensor on an a short arm from the caliper.
A good source for optical sensors are old mice, you may even find a use for the slotted discs :wink:

 

[Phasor]

I like the optical idea - You could mount it on your forks, the transmitter on one fork, and the receiver on the other, although it may be difficult if your wheels are wire-spoke type, or if you have a single-sided swingarm (like the BMW K1). Mounting it on the forks eliminates the problem of centripetal acceleration / balance :wink:

 

[abhishek singh]

existing speedo meter

hi,

most bike use same machanical coupling for speedo meter and oddometers. so removing one disables other. this exixting system can be utilized by adding optical itrruptor and counting the frequency it generates. MCS-51 family of microcontrollers supports frequency counting. as poster is familier with programming, he can learn 51 architecture and programing.


abhishek