DIY Digital gear display

[Paul Woods]

Thanks for that Jimi, thanks for taking the time to go through the circuit logic, not easy to follow!

I lay in bed last night with this circuit torturing me, i was sure there was a very simple circuit that i was overlooking, then it hit me like a bomb going off and i slept like a baby after that!

So my new design (even though the 4 relay 2 switch one works perfectly) uses NO relays at all.... sometimes i overthink things when there really is no need, the logic in this circuit is so simple a child could follow it.



Even though this one uses two more switches i like it because there are no relays.

Jimi i can't display Reverse on the 7 segment unit, the digits are pre-programmed so there is no "R", but the display will go blank using this circuit so that will have to do, also the Evora cluster has a reverse warning buzzer that you just trigger via the reverse light switch.

Hopefully these circuits will help someone else make their own display.

[Torero]

Stunning work Paul and really well explained Jimi. Even I understood it without any issue.

[Jiff Lemon]

The good old KISS principle in action right there!

Huge fan of a relay, but your switching tiny amounts of current, so massively overkill! Love this.

[thomp1983]

When you actually fit it can you put up photos of how the bits actually mount to the levet

[Paul Woods]

Thanks chaps, yep I will detail how it's all fitted too.

[Goldy]

Well done, much better without the relays, I was struggling to get my head round what we're doing with those relays

[Paul Woods]

Well the relays give an electrical way of giving true/false logic and you can also control wether they see any input on pin 30 or not, the switches have to be mechanically opened/closed to get the same logic, but yes much better without the relays in this case.

A very minor glitch has been spotted with the latest circuit, it really isn't a biggy at all, but if you notice when the stick is moved towards 1st/2nd gate or 5th/6th gate the Neutral light will go out before an actual gear is selected and also 2nd or 6th will automatically light up before a gear is engaged.

This will only be a split second before the actual gear is selected, but i have a cheaty workaround. If i move the 1st/2nd switch to the 2nd position instead of 1st and reverse its wiring then 1st will display before any gear is selected, the theory there is that 90% of the time it will be 1st that is selected anyway going across the gate, it would only glitch to 1st gear for a split second when changing down from 3rd to 2nd if you see what i mean, so while not strictly a fix, it does almost eliminate that.

The 5th/6th gate end can be done in the same way so that it pre-selects 5th just before you actually select it, now in that case that is a an actual fix as you'd never go across the gate from 3rd or 4th straight into 6th, 5th would always come first and there's no changedown to 6th so that will unglitch that end of the gate properly.

I am sure if i added a relay i could get rid of this very minor detail, but it's not an issue.

[Torero]

Nice work :thumbsup:

[Paul Woods]

Thanks John.

[Paul Woods]

So my EB60 6 speed has a separate gate selector shaft and gear selector shaft, unlike the S54 and E153 that just have one shaft that gets pulled in and out and rotated.

So my rotary switch needs to go onto the gate selector one, which is nice and exposed on the top of the gearbox with plenty of space around it and some spare bolt holes in the casing to mount the switch.

I have decided to use something already from the Toyota parts bin which will last forever, waterproof, and heavy duty. The automatic gear selector indicator switch from a Lexus RX300 is the perfect part to use. This is how i plan to use it....



Now one of the problems is that the angle between the switch contacts (called the switch index angle) is fixed, it's roughly 8 degrees between each output. Now the problem is that unless the index angle is the same on the gearbox gate selector shaft between 1st/2nd, 3rd/4th and 5th/6th then the switch is not going to align with the outputs if i mounted the switch directly above the shaft centre, the best i would be able to do is clock the switch so that at least one contact lined up, but the other two would be a lottery.

So my solution above is to mount the switch away from the selector shaft, mount an arm to the centre of the shaft, an arm onto the switch, and link them together with a small rose jointed droplink.

There are three holes in the selector arm and a slot in the switch arm, so by varying which hole i use for the droplink and sliding the other end to the sweet spot i will be able to fine tune the index angle on the switch exactly to the same angle as the selector shaft angle, it's a bit like gears on a bike i guess. For example, mounting the droplink in the far right hole and far left on the slot will greatly increase the index angle at the switch to its maximum, far left hole and far right on the slot will make the switch angle its minimum, so i figure the exact angle must be there somewhere.... pretty neat solution i thought.

So i can use three of the output terminals on this switch for the gates, and there is a dead zone for reverse, perfect.

All of this just to get a number to display on the dash!