Nifty Shift Light

NITROPIXIE · Post by **NITROPIXIE** » Tue Sep 30, 2008 5:07 pm

I bought this LED Cluster with the plan of using it as a shift light, Green to Shift and Red to show i have hit the Rev Limiter

http://www.maplin.co.uk/Media/PDFs/PD00.pdf

I was planning on connecting the power supply for the cluster (white wire) to vehicle 12v. Then the red and green wires of the cluster to variable 1K resistor (potentiometer using just 2 legs for adjustable brightness) then to the Megajolt unit for switching using the Shift Light Output and User Out 1 (for Rev Limiter).

Thinking about it a bit

1) would it be better to use the VRef 5v output to suppy power the LEDs to provide more protection? As the TPS would use or would it not be able to supply enough current. I am running Map by the way.
http://www.autosportlabs.net/MJLJ_V4_ve ... _operation

2) Can i use the Rev Limit Output of the Megajolt unit to run the Red LED on the Cluster to indicate i have hit the Rev Limit or should i just stick with Output 1???

Post by **brentp** » Tue Sep 30, 2008 6:05 pm

Hi Ryan,

With that LED cluster you definitely want to drive it from 12v. Don't drive it from the TPS output- that will place undue load on the power supply of the MJLJ, not to mention the cluster will likely be too dim to view.

I would stick with your original plan. You have 4 general-purpose user outputs, 1 dedicated 'shift-light' output, and a 'rev-limiter' output (designed to activate a hard rev limiter). As an example, you can use the 'shift light output' and one of the other outputs to make a type of '2-stage' shift light.

Regards,

NITROPIXIE · Post by **NITROPIXIE** » Tue Sep 30, 2008 6:20 pm

Thank you that answers those questions

paulc · Post by **paulc** » Tue Sep 30, 2008 9:01 pm

i bought that same cluster from brent years ago. it is CRAZY bright. i have it as a dual stage shift light.

NITROPIXIE · Post by **NITROPIXIE** » Tue Sep 30, 2008 9:08 pm

want to be able to see where i'm goin when they come on, lol so i thought i would put some variable resistors in series with them, either that or wear shades

NITROPIXIE · Post by **NITROPIXIE** » Wed Oct 01, 2008 7:24 am

has anyone used brightness of a shift light as an indicator of when its close to change gear???

what i was thinking of was to connect the cluster to 3 outputs in total, say Outputs 1 and 2 and the shift light output. For example Output 1 would operate at say 5300rpm, output 2 would operate at 5400rpm and Shift Light output at 5500rpm. Output 1 would have a 560 Ohms resistor in line, output 2 would have 470 Ohms in line and the Shift Light Output 390 Ohms all connected to the cluster.

Basically as the revs increase, each output will ground the Cluster through resistors of lesser values therefore increasing the brightness. The value of resistance would not be the lowest value of resistance but it is the sum of the resistors in parallel ie RT = (R1 x R2) / (R1 + R2), if i remember right. And if all 3 Output gates were open then it would be all 3 resistors ie RT = (R1 x R2 x R3) / (R1 + R2 + R3)

Post by **brentp** » Wed Oct 01, 2008 2:23 pm

That sounds interesting. Let us know how well it works!

Make sure you use a resistor with the appropriate power rating in your dimming circuit.

NITROPIXIE · Post by **NITROPIXIE** » Fri Oct 03, 2008 8:24 pm

Right i have done a bit of testing on getting a different brightness of the LEDs. At the moment i am just trying the best way of changing the brightness of the bulbs using a 12v supply and some resistors, not actually using the Megajolt. I am using the PSU out of a desktop computer(yellow and black wires are +12v and gnd respectively).

Firstly i tried getting the cluster to work without causing any damage but the resistors i used must of been to higher value for the LED to operate, that and the batteries i were using were too flat. In the end a 360 Ohm resistor worked a treat with the PSU to get both colours working but not at the same for some reason, probably because one of them robs more power/current than the other. Anyway i then put 2 x 360 Ohm resistors in parallel (equals half the value of one) and no obvious real difference was seen in brightness.

I then read on tinterweb that the best way to alter the brightness for an LED would be to use PWM (Pulse Width Modulation). I think this will be well OTT for the type of thing i'm after really.

I then used a 1K Ohm potentiometer (not as a variable resistor) and connected the output to one side (colour) of the cluster. By adjusting the Potential difference a very clear difference in brightness could be managed but only for a small amount of adjustment. So this has given a basis of what direction and values i can start using.

NITROPIXIE · Post by **NITROPIXIE** » Sat Oct 04, 2008 10:34 pm

A bit more testing and i'm happier with what values of resistors i wll be using. At the moment its going to be 180, 360 and 1K Ohm. So max brightness would be when the current is going through just the 180 Ohm, medium brightness would be 180 + 360 Ohm and dim would be 180 + 360 + 1K Ohm. Although i am tempted to drop the 180 lower to make it a little brighter. The best way would be to drive with them on and see if they distract me while driving. Think an optional on/off switch would be good idea at this point and maybe a daytime/night mode a bit later on.

I tried just putting the cluster to 12v without resistors and they hurt my eyes they are that bright. I only flashed them on as i didn't want to blow any and it cost me another £5. Very impressed

I am playing with some LDR circuits to have auto headlights and maybe i could have the daytime/night mode incorporated into this, maybe.

NITROPIXIE · Post by **NITROPIXIE** » Thu Oct 09, 2008 9:10 pm

Success, i set the the output options and shift light to low levels of rpm for testing and the shift light now has 3 different brightnesses of green and a bright red just before the rev limiter. I'll try to get a circuit diagram of how i have done this if anyone else is interested but so far it works a treat

NITROPIXIE · Post by **NITROPIXIE** » Fri Oct 10, 2008 8:32 am

If anyone is interested here is the link of the shift light working.

http://www.youtube.com/watch?v=DXpv3Boxgnw

In the video you can see the red light is on dimly all the time. This wasn't noticable to the human eye at the time. I think this has happened as there is no resisitor in line with that side of the circuit and thats why it shines sooo bright when it does come on.

I will leave this how it is for the time being unless i hit a problem with it. I do like the idea of how it does this at the moment cuz at night time you may be able to see the red dimly light to tell you the megajolt unit is turned on as the power for the cluster will run off the same switch the megajolt does.
You can clearly see the difference in brightness of the green leds as the engine gets closer to the shift point, i will test this as i'm driving the car to see how noticable it is and if any resistors values require changing to later brightness.

So far going well

P.S. Thanks for putting the video on you tube for me brent

Post by **brentp** » Sat Oct 11, 2008 5:44 pm

The variable brightness effect is pretty effective. Nice job!

NITROPIXIE · Post by **NITROPIXIE** » Sun Oct 19, 2008 5:23 pm

hopefully here is the circuit diagram if its worked properly

R? - i have not put a resistor in line with the red leds as yet as they seem to work ok without. A 100 Ohm value would probably be ok for some protection.

Post by **brentp** » Mon Oct 20, 2008 7:16 am

Excellent, thank you for sharing! A great way to use the outputs.

Paul(notts) · Post by **Paul(notts)** » Mon Oct 20, 2008 6:43 pm

I have ordered the LED cluster today and had a little time to think about it. Building on the above circuit it should be possible to get the green leds to get brighter, then the red come on at the same time to give Amber, then for only the red to stay on brighter for shift. - will have to play around with the cluster some switches and a selection of resistors - This is the idea I am working on.
Paul