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ecm
Apprentice
Canada
89 Posts |
 Posted - Mar 02 2003 : 7:51:00 PM
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Ive been looking to build digital speedometer for my car. do any of you know of a circuit diagram that can be downloaded with instruction.
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 03 2003 : 09:14:58 AM
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I don't know of any off hand, but what you might want to look for is a frequency to voltage converter IC. That way, you can put an optical sensor (phototransistor or the like) on the car body. Paint a white line on the driveshaft and shine an LED on it. The sensor picks up the pulses of the white line, which corresponds to the speed of the vehicle. You then run that through your frequency to voltage converter to get a voltage preportional to the frequency, which can then be read via any normal voltmeter circuit.
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DELETED (Inactive)
191 Posts |
Posted - Mar 03 2003 : 2:33:55 PM
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If you are not good in electronics, you can also take a speedometer for a bicycle. cost no more than 50$. if you want to build it your selfe, Aaron have a good sugestion. but if you plan to use it in mud, take another kind of sensor. like coil and magnet.
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ecm
Apprentice
Canada
89 Posts |
Posted - Mar 03 2003 : 8:55:27 PM
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Thank you for your input Ben and Aaron .I already have a Digital Tach schematic I would like to make a speedo meter like it . but not shure how to do it. you can have a look here http://members.rogers.com/adesorm
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 04 2003 : 10:10:07 AM
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Well, I can't really read the digital tach schematic, but the speedometer would be very similar. You just need to take your input from the pulses of the rotating driveshaft instead of the ignition coil. And of course, the display would have to be calibrated in KM/H or MP/H.
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ecm
Apprentice
Canada
89 Posts |
Posted - Mar 05 2003 : 7:36:39 PM
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thanks Aaron .
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DELETED (Inactive)
21 Posts |
Posted - Mar 25 2003 : 12:22:40 AM
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Buiding a digital speedometer would be a difficult task. A lot of things to consider. Also it would be helpful if you were familiar with how digital works. (That is if you want to design and build it) As for skematics of prebuilt ones they would be pretty involved, a couple of my friends built a digital speedometer last year, and they didn't even get to the display section of their design. Buying one that was made professionally would be the way to go
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 25 2003 : 09:53:49 AM
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I beg to differ. Building a digital speedometer is very simple. Most cars have a vehicle speed sensor for the cruise control. If the car doesn't, it is easy to add. That sensor outputs a pulse chain who's frequency changes based on vehicle speed. All you need is a frequency to voltage circuit (ICs are specifically made for that purpose) and you have a voltage that is based on the frequency and thus the speed of the car. A pre-built voltmeter module can be used to display this, you can get fancy and make your own. A little calibration of the voltage input, and you have your speed. Very simple. If you want to get into it a little more, you can paint a white mark on the driveshaft and then use a phototransistor/LED combination to read that...
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DELETED (Inactive)
21 Posts |
Posted - Mar 25 2003 : 6:34:48 PM
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You've only considered half the design, now you have to take that frequency and display it, you'll have to come up with some combinational logic to make sense out of your voltage levels that you've computed 7 seg dsiplay, but if you're going to do it with analog the way you suggest, you will have to make sure the frequency vs speed is infact linear, as well as the IC you plan on using needs to be linear throughout the region of interest
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ecm
Apprentice
Canada
89 Posts |
Posted - Mar 25 2003 : 7:13:49 PM
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nice of you to redebate my idea of a digital
speedometer. I reposted the digital tach project if you want to have a look at it and give me a input how to convert the input section.
http://members.rogers.com/tamaraki/1tach.html
my car as a V.S.S. from the manual the spec are 2000 pulses per mile or 30HZ = 54MPH .
so any idea would be greatly appreciated.
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BEatonNo1
Nobel Prize Winner
USA
1133 Posts |
Posted - Mar 25 2003 : 8:40:04 PM
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1. would it be easyer to put the sensor on the axle and multiply that times the peremeter of the tire (the distance traveled per rotation) then figure how far your going in an hour if not then
2. whan if you were to use a frequency to voltage IC and then have the voltage. that could be manipulated so that you dispaly the speed.
Edited by - BeatonNo1 on Mar 26 2003 3:45:01 PM |
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DELETED (Inactive)
21 Posts |
Posted - Mar 25 2003 : 11:03:09 PM
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What exactly are you looking to convert? I checked out that webpage...and their idea of "simple" is a little different than mine, I'm not saying that what they did is wrong, it just seems like a rather complicated design, but from what I could see it made sense, but for the most part...it would be easier to buy most of that stuff rather than build it on a circuit board. Let me know what you think
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 26 2003 : 3:45:55 PM
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Um, you seem to be missing half my post. The output of the circuit is a simple voltage. There are many "1 chip" voltmeter and display solutions.
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BEatonNo1
Nobel Prize Winner
USA
1133 Posts |
Posted - Mar 26 2003 : 4:45:05 PM
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Oops sorry Aaron must of skipped over that post.
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 27 2003 : 10:20:22 AM
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quote:
Oops sorry Aaron must of skipped over that post.
Sorry, I was referring to jjenshak. 
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BEatonNo1
Nobel Prize Winner
USA
1133 Posts |
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digital speedometer
