DIY digital temp gauges
 

I've always wanted dual digital gauges, but not for $300 (Spa brand):

Attachment 196040

If someone can find an inexpensive (~15) LCD backlit green voltmeter panel gauge of the right size, I will design a circuit to read off of the factory water temp signal, and off of a $1 oil temp thermistor so it will read oil and water temps. An EGT circuit is easy too.

The panel meters have to be small enough to stack 2 vertically by 3 wide in the miata's panel below the stereo.

Here is what I mean by panel voltmeters:
http://media.digikey.com/photos/C-TO...K203,DK204.jpg

However in this example (a) it has no backlight and (b) it is too tall to stack 2 vertically.

With small enough meters, one could replace the factory temp gauge in the dash with dual oil and water temp too....

FWIW backlit LCD is better than LED because the latter is hard to read in sunlight.

not DIY, but not too expensive:

http://www.vgauges.com/catalog/produ...products_id=83

Nice find but, it's:
- LED
- you need to install its senders ($18 each)

I had some panel voltmeters I converted to read Wideband 0-5V signals and turn them into AFR.

Jason: can you post up a schematic for the "share the sensor" circuit for water temp?

I haven't designed it yet

i know, just giving you the option. i bet you could get the same senders for $3 each.


maybe i could get shuiend to measure the scale of his?

NEVARZ. Ok what do I need to measure and what is the easiest way to do it?

http://www.diyautotune.com/tech_arti...alculation.htm


something like that. the body of the sensor is ground. I'm sure they are a generic sender you can pick up for a song. I dunno...

That looks like so much work. It might possibly happen, we will see.

exactly.

If it's been installed already, just unplug the harness and read the resistance when:
The engine is at room temp.
The engine is partially warmed up.
The engine is hot.

I'd be interested in these DIY temp gauges.

BTW how easy are these to read in sunlight?

based on innovate DB gauge...going with: impossible.

Um they are sitting in my engine on my engine stand. I might pull one out to test the sender tonight. I just need to find a thermometer tonight.

That I do not know, I just bought the 2 senders for now. When I am done with my engine build and have spare money I will pick up the gauges.

i was kinda sad after i replaced my narrowband gauge for the DB (same as blue pictured above, mines red) the first time i drove with the top down. so i enabled the AFR safety code.

For posterity's sake, I measured the factory temp gauge in my '00 cluster. Diameter of the visible area is 1.67", depth of the gauge itself is 1.2".

2 of these stacked vertically would juuuust fit, but no backlight!


http://www.lumex.com/images/uploads/LCD-S2X1C50TF.jpg
http://media.digikey.com/photos/Lume...1C50TF_sml.jpg
http://www.lumex.com/specs/LCD-S2X1C50TR.pdf

$3 at Digikey:
http://parts.digikey.com/1/parts/679...s2x1c50tr.html
That one is reflective.

Here's the "trans-reflective" version of the same thing:
http://search.digikey.com/scripts/Dk...ame=67-1798-ND

Trans-reflective means you can read it with ambient light, *and* you can also backlight 'em.
I just might buy some to play with it, see if I can add backlighting.

Very nice looking unit, and the backlight modules are pretty cheap as well.

One thing that occurs to me about the specific units you posted, at least in a temperature-reading application, is that they can only display a maximum reading of 199°. Well, actually that's not true; they could display a maximum value of 511°, but only if you enjoy doing hex-to-decimal conversion in your head in realtime.

They do have three-digit units which fit in essentially the same outline, though the characters are much smaller and are spaced out a great deal more. http://search.digikey.com/scripts/Dk...rds=67-1799-ND

http://www.lumex.com/images/uploads/LCD-S301C31TR.jpg

I will display in Celsius. :)
Remembering "100*C" = boiling and "120*C" = "freaking hot" is easy. :)

Here's a 128x64 dot matrix, serial comm, includes the backlight. Perhaps it can be shoehorned in the gauge cluster:
http://www.sparkfun.com/products/710
http://static.sparkfun.com//images/p...cal-2_i_ma.jpg

Dimensions:
Overall: 75 x 53 mm
Viewable area: 55 x 27.5 mm

Of course only a portion of it will show, but that's enough to display oil and water temps

And they have LCD's galore:
http://www.sparkfun.com/categories/148

I actually kind of like the idea of a graphical display better. I find analog instruments a tad easier to read quickly, and you could easily implement 3 or 4 bargraph displays on that, along with absolute numerical values. This would of course require a microcontroller to implement, but that comes with its own set of advantages as well. One would be the ability to program it to send out-of-boundaries conditions (water or oil temp above a maximum, oil pressure below a minimum, etc) and flash the whole display annoyingly to more immediately grab your attention.

Heck, I could plausibly see water temp, oil temp, oil pressure and fuel level all on one gauge, leaving the other two holes in the factory cluster open for manifold pressure and AFR. :D

this would seriously be sweet. I'd love to get my XD-16 as well as real oil pressure and water temp into the cluster... a gauge like this http://www.vgauges.com/catalog/produ...products_id=77 in the fuel gauge location, XD-16 in the water temp location, and relocating the fuel gauge somewhere else would be great, but things would not flow well visually.

And more
remember the display area of the temp gauge in the dash is a 40 mm hole.

100x32 dot matrix
65x32 mm overall
display is 38x14 mm
backlit
http://www.newhavendisplay.com/index...ex&cPath=21_92

http://www.newhavendisplay.com/image...front-NOBL.jpg

Here's a 1x8 char display
overall dimensions 53x24 mm
chars are 7.1 mm tall, total width 33 mm, backlit

http://www.newhavendisplay.com/index...roducts_id=202
http://www.newhavendisplay.com/image...-front_MED.jpg

And a 2x8 (you can display oil temp, water temp, EGT, and kPa :))
http://www.newhavendisplay.com/index...roducts_id=259
Overall 40x35 mm
chars are 5.1 mm tall, 26 mm total width, backlit
http://www.newhavendisplay.com/image...-front_MED.jpg

I just bought one of these and I'm (ever so slowly) writing code to make it work with ms2 and ms3 over serial... It has a speaker, so I'm going to set it up to make obnoxious warning noises if anything gets out of range. Going to run a gm coolant sensor in my pan as oil temp, and not use any aftermarket gauges.

Borrowed the idea from that aussie guy who used the OLED version in his cluster, I'm just going to mount this under my radio... I figure you don't have to look at it all the time if it warns you.

http://www.sparkfun.com/products/10089