Race style LED shift indicator. How do I make one?? Electronics wizards please--->

509 Views 21 Replies 9 Participants Last post by 6g72tt, Nov 6, 2001

PearlR/T

Discussion Starter · Oct 25, 2001

Race style LED shift indicator. How do I make one?? Electronics wizards please--->

Has anyone seen the style of shift lights that they use in most racing like F1 and others? They have a line of LED lights that go from green to yellow to red. I want to know how to make this. What would they get a signal from? Would it be really hard?
Thanks in advance,

1 - 20 of 22 Posts

PearlR/T

Discussion Starter · #2 · Oct 26, 2001

ttt

Beast

· #3 · Oct 26, 2001

I seen nordskog makes a digital gauge like your talkin about.
In summit race catalog.

You could probably make on somehow with
a variable resister emitting voltage to light emitting
diodes (LED)

Lawrence Wang

· #4 · Oct 26, 2001

Re: Race style LED shift indicator. How do I make one?? Electronics wizards please--->

PearlR/T said:
Has anyone seen the style of shift lights that they use in most racing like F1 and others? They have a line of LED lights that go from green to yellow to red. I want to know how to make this. What would they get a signal from? Would it be really hard?
Thanks in advance,

I made a bar graph tachometer just like you describe a while back (some people who were at GT Pro that day might remember it) but I got lazy and never installed it

National makes a bar graph LED driver, so it's real easy. Just need a divider, some source of power, your LEDs, the driver chips, and you're good to go. I tapped off of the tach (since the 2nd gen. 3kGT SL had an electronic one.)

jamb53

· #5 · Oct 26, 2001

Pics please!!

Lawrence, send pics man. That is an intriguing idea. I think it'd basically be a LED tachometer, effectively - right ?

Lawrence Wang

· #6 · Oct 26, 2001

I already gave it to a Supra owner while I was in school...I still have parts though, and will build another one up in a few days.

PearlR/T

Discussion Starter · #7 · Oct 26, 2001

How much does it cost to build and where did you get the parts? Could you tell me or send me some kind of instructions? I would really like to do this. I can get plenty of LEDs. Is my first gen tach the same as the second gen?
Thanks,

VBBlckBlt

· #8 · Oct 26, 2001

i suspect that first gens use cables, not electronic. Isnt the speedo that way? Could be wrong...

Lawrence, you have that partnumber for the drivers handy? I may wanna use that in a turbo timer im building...

Im like you...I already built a turbo timer (using 555 and pot), and its just been sitting there. Now comes the PIC version

Roger G.

· #9 · Oct 26, 2001

My ERL System 2 Water injection comes with a digital rev LED, hehe. This is used to control the 3d map functionality but can be used for some shift light stuff too.

BTW, MSD has something liek that in their program too.

Lawrence Wang

· #10 · Oct 26, 2001

The driver chip is the 3914 from NS. Be sure to get the PLCC version, as the 18-pin DIP is just huge.

PearlR/T

Discussion Starter · #11 · Oct 26, 2001

Okay, sorry, but can anyone give this to me in lamens terms. I am good with electronics, but I don't know what everything is called or where to get it.
Thanks,

QuonoS

· #12 · Oct 26, 2001

That might be a little bit of work, but not too bad. I'm a computer Engineering student right now, so its up my alley. If you want to talk to me about how to do, I'll tell you a good method of doing it, and then see if you can handle it. send me an e-mail at [email protected]

Lawrence Wang

· #13 · Nov 5, 2001

Welp, I finally got around to building the bar graph tach this weekend...built it last night. Borrowed a digital camera from a friend and took a little movie of it, but he left the little dongle for it at work, so hopefully he'll bring it back tomorrow. I'll post the movie when he gets it xferred to a computer.

PearlR/T

Discussion Starter · #14 · Nov 5, 2001

Hey that's great! Be sure to post it when you get your "dongle" back.

VBBlckBlt

· #15 · Nov 5, 2001

yeah also post the schematics for benefit of fellow auto-enthusiasts

Lawrence Wang

· #16 · Nov 5, 2001 (Edited)

Schematic

Seems they won't let me attach a file bigger than 100kB; hope it's readable.

Edit: Oops, forgot to draw in integrator.

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VBBlckBlt

· #17 · Nov 5, 2001

coolio...now whats U9?
and we're gonna need values for those components too...
you could just post them in the thread, and some of us could make a page or something that tells how to DIY!

Lawrence Wang

· #18 · Nov 5, 2001

U9 is any Buck regulator...I used a 2671 just because it was handy. You could use a linear regulator too, but it would create more heat and you'd also have to create a separate clock for the reset FETs. C1, C21, and C22 are bypass caps. I used some 3.3uF tantalums. C23 and C24 can be anywhere from 1nF to about 50nF. R1-3 set the current through the LEDs...REF OUT is nominally at 1.25V to ground and 10x the current that you draw through the resistor will be programmed through the LEDs. For all the diodes, any general-purpose signal diodes are OK, though for better efficiency, use a good low-drop Schottky for D20. R20 is a small value to reduce device heating in the ICs if your regulator is set significantly above an LED diode drop. R4+R5, R9||R13, R10||R15, R11||R14, and R12 should have similar values. Note that R4+R5 also sets LED brightness for the highest bank, so choose that value similar to R1-3. R16-19 are small buffers, as are R32, R33, R31, R30, R34. C25 should be chosen for about 1% droop or so over a few hundred msec. R27, R28, and R29 should be chosen for a fairly long constant in conjunction with C25, or else there'll be lots of ripple in the output. Mine has a Norton equivalent resistance of about 1M, might be too much. R26 and R25 should be matched (duh.) R21-24 forms a bridge with R22 half the resistance of the other three. The inductor can be any value...not important really since no one will care of the LEDs' brightness varies a bit. Remember to bypass the opamp supplies well, and keep the input impedance relatively high so that you won't disturb the operation of the normal tach but not so high that it'll pick up noise.

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akira410

· #19 · Nov 5, 2001

Lawerence,

Did you ever figure out a way to filter out the pulses?

Lawrence Wang

· #20 · Nov 5, 2001

akira410 said:
Lawerence,

Did you ever figure out a way to filter out the pulses?

Yeah, I was just too lazy before to design a real active integrator

This setup works fairly well now, only have about 20mV ripple at worst case.

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