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ReBorne
Apprentece
United Kingdom
13 Posts |
 Posted - Dec 21 2004 : 4:02:03 PM
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I'm converting the whole dash to digital in my poor old Mini (in the UK). Maplins sell a tacho circuit that will be fine as a speedo, I've picked up a circuit with a line of LED's that light up for the rev counter. Now I just need a simple circuit for the temp gauge and the fuel gauge.
Once again, I want these to be indicated by a line of around 6-8 LED's. A search on the net has produced sod-all so far, so has anyone got a circuit diagram that would do this?!?
Cheers!
Mike.
btw, I found a complex cicruit (sorry, can't remember where) for indicating which gear the car is in..... it worked out about £40...... It may sound daft, but I'm just gonna use 5 micrswitches and a bit of Veroboard and a 7-segment LED.... When you put the car into gear, the gearstick physically switches one of the switches 'on', power goes to the relevant segments of the LED! Cost me about £3......
(Just had a brainstorm - a discount shop sells those little contact alarms at 3 for £1..... I attach a magnet to the gearstick and use the reed switches!!! Less accuracy needed too.... rofl) |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Dec 22 2004 : 09:15:48 AM
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I'm looking at the same thing for my Insight (want to monitor EGT, engine temp, vacuum, etc.) as a bike I'm building (but I will likely use the instrument cluster from the car that is donating the engine).
There's a circuit on my circuits page at http://www.aaroncake.net/circuits/vumeter.htm that should do the job.
Have you looked into the Dakota digital dashes? Also, Summit Racing (and I assume most other suppliers) have a variety of digital gauges.
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ReBorne
Apprentece
United Kingdom
13 Posts |
Posted - Dec 23 2004 : 04:41:18 AM
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Cheers Aaron. Couldn't be much simpler could it?!?
Only concern, you say the input voltage needs to be 1.3v max. I haven't actually checked the voltage yet (no engine in it......) but I presume it would be higher than that?
You'll know from my other posts I'm a thickie when it comes to calculations / electronic theory etc, so how would I get the voltage down if this was the case? Would it just be a case of throwing a resisitor in line?
Cheers!
Mike.
p.s. when you get yours done we'll have to see some pics!
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Aaron Cake
Administrator
Canada
6718 Posts |
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ReBorne
Apprentece
United Kingdom
13 Posts |
Posted - Dec 24 2004 : 04:53:36 AM
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Once again I humbly thank you *bows*
Your help has meant that even a divvy like me should be able to create a dash that looks.....er..... dashing... lol
You knoow, considering that even I can understand these circuits, I'm absolutely amazed digital gauges aren't more common in the custom scene. Personally, the only reason I'm not buying a professional one is that the budget for the whole car is being kept as low as possible. (Not just coz I'm skint, but also to prove that you don't have to spend a couple of grand to get a decent looking / sounding car.)
Once again, cheers!
Mike
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Dec 24 2004 : 09:30:04 AM
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It depends on the car. In my RX-7, I would never consider digital gauges. Analog gauges can be read at a glance, without having to comprehend the numbers that are actuall displayed.
The Insight has a factory digital dash, which is actually quite good. But at times, it can wash out in the sun, and the direct numerical readout for the speed takes some actual thinking to figure out.
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GMP
Apprentece
15 Posts |
Posted - Apr 02 2005 : 12:10:36 PM
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Sorry to bring up this old post, but I was wondering- The circuit posted on the site is for audio and uses LM3915 which is a logarithmic display. Wouldn't you want a LM3914 for linear movement? I am curious if these analog meters are linear or log.
Thanks,
-George |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Apr 03 2005 : 10:50:20 AM
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Most cars nowadays use logarithmic gauges for things like fuel, temp and oil pressure (LOL, if they even include temp and oil pressure). The idea is that the user doesn't want to see every gallon disappear from the tank, so the gauge is more sensitive after the tank is half empty. Same with temp. Drivers get concerned when they see their temp rise when they load the engine, so most gauges simply don't show it.
Things like the tach, speed, etc. are of course linear.
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Suprised this hasn't been asked.....
