signal splitter for tachometer

[Sanec]

After installing V6 instead of i4, tachometer began to show rpm and a half times more.
Is it possible to solve this problem and make the compensation selection to cover a lot of options?

[jbelanger]

It is possible. Which options would you see as needed?

Jean

[Sanec]

Selection of the transformation ratio. But if you think about versatility here is not necessary. The main thing that was a choice when ordering.
Another question on adjustment signal to the speedometer. There is important modifiable factor, a variable resistor. Assuming for one half vref. To be able to adjust on the fly speedometer, without giving the number of pulses.

[jbelanger]

A fixed ratio for a tach is relatively easy. Even allowing many different ratios that can be selected through DIP switches or jumpers is not a problem.

But having a variable speedometer adjustment if quite different. First the range of frequencies is huge because you can have from a few hundreds pulses per mile to hundreds of thousands. Also it would likely need to be adjustable up and down to be truly useful so that means the range of adjustability needs to be relatively large too.

So the change of ratio could be done as a firmware change on the PWM converter board. But the speedo adjustment won't be something I will consider at this time. If I can see that there is some interest, I may do it so people should post here. Which ratio would you like to see? There could be up to 8 different ratios selected from the 3 jumpers and if need be there could be more than one firmware version for more ratios. And remember that 4->6 is not the same as 6->4 (but it is the same as 2->3 and 8->12).

Jean

[Sanec]

4->5
4->6 (2->3)
5->6
5->4
6->4 (3->2)
6->5
8->4 (4->2)
8->5
8->6 (4->3)
and other...

[jbelanger]

Since I would only have 8 ratios available, I think the following would cover most likely cases (the first number if the number of cylinders of the original engine and associated tach and the second number is the number of cylinders of the new engine that the original tach should support):

3->4 (6->8)
4->5 (8->10)
4->6 (2->3, 8->12)
5->4
5->6 (10->12)
5->8
6->4 (3->2)
6->5 (12->10)

Since the MS code already covers the divide by 2 (2->4, 3->6, 4->8, 5->10, 6->12), this is not included. Also, I haven't put the 8->x because I don't think this is very common. However, as I mentioned it is always possible to do a second firmware version if that becomes necessary or the list can be changed if my list doesn't correspond to what people need.

But I will need to see some posts from people saying they would buy the equivalent of the PWM converter kit before I will even start looking at the code. From my experience on many requests, even many people saying they need it and would buy it tomorrow doesn't mean much unfortunately.

Jean

[Sanec]

the best solution would be to examine the demand without changing the board. Or send now only controller. I am satisfied with both the decision and is willing to take a couple of sets at once.

[Sanec]

if the inputs and outputs to 0-5, 0-12 then the product will be of interest and the common people for example have a huge array of Nissans were installed along with a 4 cylinder engine 6 (8) cylinder engine rb, jz, ls.

[jbelanger]

The idea is to keep the exact same board and kit as the PWM converter and just change the firmware. But I need to see more feedback before I implement this code.

Jean

[dontz125]

Another question on adjustment signal to the speedometer. There is important modifiable factor, a variable resistor. Assuming for one half vref. To be able to adjust on the fly speedometer, without giving the number of pulses.

What you're asking for is a "Speedo healer", more often used by bike guys, who are more likely to change their wheel and tire sizes as part of an upgrade / mod package than car guys. I have a design that I can finish and offer for sale, if you're interested.

(I did ask Jean's permission before posting this - not my site to advertise stuff otherwise! )

[Sanec]

I have a design that I can finish and offer for sale, if you're interested.

I wonder how much it costs?

[jbelanger]

Check the msextra forum. Don has a post there on this.

Jean

[dontz125]

Speedo corrector from TTR Ignition Systems:

When you change your rims, or tires, or diff, your speedometer usually doesn't read as accurately as it used to. Sometimes this isn't a big deal, sometimes it is - certainly, the nice policeman doesn't want to hear about how all the mods you've made have thrown off your speedo!

We now offer a small, easy to use module that wires in between your speed sensor and the speedometer, and allows correction to put the readout back where it should be. Using a single multi-turn pot, stepless adjustment can be made from 2.5% to 250% of the input frequency. Calibration test points inside the housing allow the use of a multimeter to quickly dial-in the adjustment.

The Speedo Corrector will sell for $60, and can be ordered here.