I've come across this on the internet, it's a schematic for a gear position indicator. What do you guys think? Possible a good little project? It's for the new generation gixxers
The instructions are:
This circuit is an example of how you can build a gear indicator for suzuki motorcycles which have an OEM gear position sensor (GPS). It basically uses comparators to compare the voltage coming from the GPS to predetermined levels and then will ground the negative lead of the appropriate LED on the display. The LEDís will be lit up in a continuous style (for example: 1st will light up the 1st LED, 2nd will light up the 1st and 2nd LED, 3rd will light up the 1st 2nd and 3rd LEDís, etc. etc.
An explanation of the parts required:
U1 = 5v regulator so that reference voltages do not vary with source voltage.
R1-R7 = The resistors form a ladder that breaks up the 5v from the voltage regulator (U1) into reference signals to determine at what voltages the LM339AN will use to ground each corresponding LED. It is important to use 1% resistors to make sure you get exact reference voltages because in the higher gears the signal is very close and there is not much gap between voltages:
The output voltages from the sensor are as follows
1st gear = 1.782v
2nd gear = 2.242v
3rd gear = 2.960v
4th gear = 3.630v
5th gear = 4.310v
6th gear = 4.660v
Neutral = 5.000v
The comparators in this circuit will turn on each LED as follows:
1st LED = Anything over 1.022v
2nd LED = Anything over 2.043v
3rd LED = Anything over 2.660v
4th LED = Anything over 3.356v
5th LED = Anything over 4.052v
6th LED = Anything over 4.526v
With this setup, Neutral will light up all 6 LEDs because it is over 4.526v. This is usually not a problem because it is difficult to get 6th gear and neutral confused. It can also be helpful because it will give you an indication if there is a false neutral situation. All lights will flicker on and off as you shift gears because for a brief instant you are in a false neutral.
R8-R13 are current limiting resistors for each display LED. This is to control the brightness of the LED and also prevents the LEDís from drawing too much current and burning out.
This circuit also has a built in dimming feature which is why there are (2) 12v sources. The first one supplies voltage to the circuit and also to the LEDís. It goes through a diode (D1) for reverse protection and then through R14. R14 keeps the LEDís dim for night riding when the high beams are usually off. It is required to be on a 12v source that is on whenever the bike is on. Since it is dark out, seeing the LEDís will not be hard. For daytime riding, when the high beams are usually on, the voltage comes from the 12v high beam circuit which also goes through a reverse protection diode (D2). There is no resistor here to allow the LEDís to shine at their maximum brightness for easy visibility in the daylight.
For clarity, some points were not connected. Letters a, b, c, d, e, or f, should be connected when the circuit is built.