Shift Light

This was my solution after a very long journey to get a correct rpm signal and shift light to a modern speedo unit.

kzrider.com/forum/4-electrical/611461-rpm-signal-noise#811053
kzrider.com/forum/4-electrical/607690-de...lectronic-tachometer
www.kzrider.com/forum/4-electrical/61087...age-nightmare#805851





 

wrote:

This was my solution after a very long journey to get a correct rpm signal and shift light to a modern speedo unit.

kzrider.com/forum/4-electrical/611461-rpm-signal-noise#811053
kzrider.com/forum/4-electrical/607690-de...lectronic-tachometer
www.kzrider.com/forum/4-electrical/61087...age-nightmare#805851





 

Thanks Scirocco - some really interesting stuff there, from what I can see it all relates to a fluctuating tacho needle issue. I don't think this would be an issue with a stand alone shift light that is made to work from a coil pulse and has no needle (I guess time will tell  ) If you need to go with both coils the below should work for you
 

wrote:

If you need to go with both coils the below should work for you
 

I think the diodes need to be reversed.  First, as I quoted from the shift light manual in a previous post, the shift light manual says, when adding diodes, the diode should point towards the shift light.

Second, if you imagine a simple system with a long dwell time, the negative coil wire spends most of the time grounded and is only briefly released to fire the plug.  In this situation it's very likely that when one coil wire is high, the other wire will still be grounded.  With the diodes pointing towards the coils, if either coil is grounded the shift-light input will be held at ground and won't see the firing pulse.

wrote:

wrote:

If you need to go with both coils the below should work for you
 

I think the diodes need to be reversed.  First, as I quoted from the shift light manual in a previous post, the shift light manual says, when adding diodes, the diode should point towards the shift light.

Second, if you imagine a simple system with a long dwell time, the negative coil wire spends most of the time grounded and is only briefly released to fire the plug.  In this situation it's very likely that when one coil wire is high, the other wire will still be grounded.  With the diodes pointing towards the coils, if either coil is grounded the shift-light input will be held at ground and won't see the firing pulse.

If you reverse the diodes the shift light will have no path to ground to create the pulse 

wrote:

If you reverse the diodes the shift light will have no path to ground to create the pulse 

The shift light has three wires: Power, ground, and pulse.  The shift light ground would be the current path for the pulse signal.

wrote:

wrote:

If you reverse the diodes the shift light will have no path to ground to create the pulse 

The shift light has three wires: Power, ground, and pulse.  The shift light ground would be the current path for the pulse signal.

The pulse can only be positive or ground, I guess ultimately you would need to know from the manufacturer weather the unit is looking for a pulsed live when the ground is broken or pulsed broken ground - this would determine the orientation of the diodes
EDIT: Been thinking about this on my drive home from work, DOHC your point about the dwell overlap makes complete sense and in hindsight the logical answer in this case would be that the pulse would be positive when the ground to the coil is broken. Therefore the orientation of the diodes would need to be reversed to that in the diagram - Happy to admit when I got it wrong