Shogun Digital Speedometer KOSO STYLE

This is a continuation of the digital speedometer by KOSO taiwan, that I modified to accept digital speed sensor, instead of the original cable type used by Yamaha MIO. The modification intended for use with those sensor found on Raider R150, (Satria and or Belang 150), Shogun R and Pro, as well as Shogun Best 125 and Wave 125 S. They used the Variable Reluctance Sensor fitted at the back of the engine which reads the driveshaft gear of the motorcycle.

The Koso For MIO original way of reading the speed of the motorcycle when fitted was using a speedometer cable and connected to the picture shown. And the other end of the cable goes to the gear assembly connected on the front wheel hub. Not all motorcycle has that gear assembly for others uses digital sensor I have said before. The question of many was. How can we be able to use the Koso for mio on other motorcycle if we want to modify and use it?

The answer rely on this article. First we need to understand how the KOSO for MIO works.
Shown is the view of the Koso original speed mechanism.

The magnet rotates on a hall sensor soldered on the PCB board of the Kos by the speedometer cable attached. When this magnet rotates on top of that hall sensor, It produces magnetism

The Hall sensor I am telling all of you about is shown on this photo.It will be remove for the modification to work later on because an external circuit will replace that hall sensor as an additional pulse shaping adapter for the Variable reluctance sensor. Both sensor differs in many ways, so by just replacing the latter to the hall sensor will definitely not going to work properly.

HALL SENSOR--A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications.




 


VARIABLE RELUCTANCE SENSOR use variations in magnetic-field densities created by changes in reluctance within a magnetic circuit. It has its own magnet, and changes on that magnetic field produces pulse.






So their principle on how they work differ thus if we just replace one another without an additional circuit will definitely not able to work and produces irregular speed reading. I tried it already. A 20 kph reading on the original hall sensor will give out 300kph on the reluctance and even with the lowest calibration possible of the software of the unit, still gives a high speed reading.

At first I tried replicating the original speed sensor circuitry of the original Shogun 125 (FD125XRM) panel board. I mean the ORIGINAL OEM speedometer assembly, But for unknown reason still fail with my test, until a friend brought me something. A replacement speedometer assembly of the shogun. A direct replacement to the OEM which has a different circuitry. I analyze that circuit and manage to extract that single block that allows the pulse to be shaped entering the micro controller IC that is easier to understand rather than the complicated MCU of the original OEM panel.

Sorting the single block the performs the duty of pulse shaping. and isolating it. I made it worked on the KOSO and use the reluctance sensor. VOILA!!!! it did work.

I made a stand alone PCB using the same components and put it on single sided board. I used Diptrace Circuit maker for making the outline and transfer it to the PCB for etching. To make it smaller, I used SMD components. and the final etched was so small, i have nothing to worry placing the add on circuit at the back of the KOSO board.

The variable reluctance sensor needs an external supply to work since the original OEM panel board was replaced to where it was getting own supply. It needs to be supplied otherwise by the koso board which is 5 volts. Red wire comprises it directly to the original connector of the shogun panel..Note the KOSO has its own connector so be advice to work out on it on how to re wire everything without cutting wire, so that when you want to return the original speedometer panel of shogun..just pull out the koso and fit the original as plug and play..Always make it a habit that when you do such modification..do not alter the original wiring for EASE of access later on when everything fail.

Photos 

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