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Spark727
Apprentece
6 Posts |
 Posted - May 31 2006 : 12:53:45 PM
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Hi everyone,
i would like to build an speedometer, what uses DIGITAL (3 dts.) and LED (about 60-80 pcs.), can anyone help me with the schematic for it???
i would like to post the design of the speedometer, but i don't know how to upload in here.
Please help
many thanks in advance
freddie 
Edited by - Aaron Cake on Jun 01 2006 09:04:38 AM
Edited by - Aaron Cake on Jun 01 2006 09:09:18 AM |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Jun 01 2006 : 09:08:01 AM
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You can insert an image into your post by using the [ img ] tag as described in the FAQ.
A speedometer is fairly easy to make. You need some kind of pickup (optical or magnetic) that creates a train of pulses whos frequency varies by speed. Generally this measures the rotation of the driveshaft or CV joint. You then feed that to a fequency to voltage converter (this is commonly available in IC form) and then output that voltage on a voltmeter (display drivers with built in analog to digital coverters are available as well). A gain control between the frequency to voltage and display allows you to a calibrate the device.
Also, I changed your subject line to something more appropriate. Just posting "help!" doesn't really provide much information as to what is in the topic.
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Spark727
Apprentece
6 Posts |
Posted - Jun 01 2006 : 10:48:12 AM
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Hi Aron,
thanks a lot for your help and posting, here is my design of the speedometer i want to build, ' ![]() so hopefully someone has a similar schematic available.
I been googeling for a while, but could not find anything like, only "either / or".
So Please help somebody
many thanks
freddie
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Spark727
Apprentece
6 Posts |
Posted - Jun 01 2006 : 11:26:36 AM
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quote:
again, i can not attach the picture (i don't have a website) sory
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cirvin
Nobel Prize Winner
USA
1542 Posts |
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Spark727
Apprentece
6 Posts |
Posted - Jun 02 2006 : 05:33:02 AM
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Hi,
i agree, and i have that already, but i think it will br more accurate if i use an "Hall-Sensor", then the permanents.
there are two ways of getting the amount of Engine-turns.
One is to use the 'Hall-Sensor' of recently designed Ignition-Systems or using the Interruptor-Kontakt at Ignition-Coil of older Modells. This Methode has the gap, that Iginitions come at every 2nd turn for each cylinder. So, in my case, it comes three times of real turns. (n=I/3).
The other methode is to use the Hall-sensor at CAM, which Pulses with half of the Engines turns.
You have mentioned a Methode of taking the turns by extra coil and Permanents directly from Motor-Shaft or behind the gearbox. (Where you have to distinguish between Vehicle-velocity (after gearbox) and Motor-turns.)
A good Dashboard is also an instrument of worth-measurement, because it tells a potential vendor the mileage of the Vehicle. So anyone will asume it as 'InManipulateable'.
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Jun 04 2006 : 10:31:06 AM
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Hall sensors are very accurate. They are used all over the place, including a triggers for the ignition and fuel systems in may modern engines. For this project they are likely the easiest sensors to work with.
If you also want to measure engine shaft speed (RPM) then you use a similar circuit. You just may have to add a multiplier digit to the meter.
cirvin posted a great circuit. I may make on for my scooter.
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cirvin
Nobel Prize Winner
USA
1542 Posts |
Posted - Jun 04 2006 : 11:18:06 AM
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Another version of that circuit I found is a frequency counter, I'll have to pull that up later, I don't have the bookmark here.
http://daxter12.topcities.com <Updated:July |
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james j mcgee
Apprentece
USA
7 Posts |
Posted - Mar 15 2007 : 11:59:41 PM
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I would like to make a LCD combo Speedo/tach for my Harley My new wheels dont have a speedo output of any type and I cant see spending 350-500 bucks on a digital set up. I can CNC a nice Aluminum mounting box. Anyone know how that circut would hook to a lcd panel?
Thanks
J |
J |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 18 2007 : 10:53:54 AM
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Both cicuits are fundamentally the same. You'll read the RPM via the ignition coil and then feed it to a frequency to voltage converter. Check out the Megasquirt schematics at http://www.megamanual.com for some good circuits to interface to the ignition coil.
Speed is the same, except you would use a Hall sensor which will offer a direct 5V pulse train out. You can then read these with a microcontroller and convert the output to a serial signal following the protocal of the LCD screen you use. |
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Help:Looking for schematic for digital speedometer
