Electronically read RPM

[ILMV]

Good day all,

Is there a way to read the RPM of an F800GS electronically? Want to hook it up to a prototype board for a bit of hacking

 

[rce]

Easiest way is monitor coil supply or an induction module on spark plug lead

 

[JayC]

A Trail Tech Vapor speedo maybe?

http://www.ebay.co.uk/itm/TrailTech...25?pt=UK_Motorcycle_Parts&hash=item20b8031e79

 

[ILMV]

Cheers rce.

JayC, that isn't what I'm looking for, want to program an Arduino circuit board to read in the rev value.

 

[rce]

I would be inclined to make an interface circuit using a high speed opto isolator, back emf diode across LED side of opto to protect opto but not interfere with bike electronics eg suitable resistor to opto input with diode across opto input to protect against back emf.

 

[ILMV]

Oh my, I'm seriously new to electronics and what you've just said has gone well over my head :O

I appreciate your suggestion, could you explain for a n00b?

 

[rce]

This covers opto isolators

Put simply an opto isolator is an LED and a light operated switch in one package.

In your application the LED is across the coil and the switch is wired to your logic board input.

You can't just put the LED straight across the coil it needs a resistor in series, something like a 1k resistor.

The LED is sensitive to reverse voltage, therefore you wire a diode across the LED connected in reverse polarity to the LED.

The output from the opto (the switch bit) is then interfaced to an input on your logic board.

A simple opto circuit, if you are still stuck you need to ask specific questions rather than a general one as too many ifs or buts otherwise.

http://imageshack.us/photo/my-images/38/opto.jpg/

In that picture your diode would go pin 1 to 2 and the 330ohm resistor would be 1000ohm, the output 7&8 would probably direct to your logic input.

 

[rce]

Oh and you need an opto that can handle 150Hz, your logic system needs to also handle 150Hz if you want to cover the normal rev range.

 

[ILMV]

Cheers for explanation rce, that makes sense now