New mechanical speedometer drive solution
02-28-2012, 01:28 PM
#102
Just a status update on the logical/electronic portion of this project - the base code for the embedded program compiles and loads fine. I am still tweaking the motor power supply design for the final (need to make sure it can take supply tension loaded up to 35v, isolate errant currents and filter high frequency noise, jitter, and compensate undervolt conditions down to 9v), but my base PSU and amplifier designs are currently running on a breadboard on my bench and driving the motor well. Tim is taking care of the mechanical aspects of the design like a boss, so we're looking good. I still need to write the calibration and test signal generator modules. Should get to that by tomorrow night.
Ok all i understand out of all that was motor power and tomorrow night
You guys are doing some Great work keep it up and make all use LS guys happy to have are Speedo back working in are old cars.
02-29-2012, 06:49 AM
#105
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02-29-2012, 07:13 AM
#106
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So true! I looked at the cable-x and it has some somewhat major issues. 1st the motor often has issues at low speed, Also if the cable from the motor/box to the speed has any curve at all in it the speedo may not start turning till like 15-20Mph.
Before this thread started I was also looking into building something like this for my car, I already purchased the micro controller, looked at different pickup methods etc etc. They are one up on me here in the thread as I have been having problems finding a motor that should work at say 3-4 MPH at extended times. At very low speed, is were these motors are very inefficient and that can lead to heat problems, or plain just motors burning out etc.
If anyone is looking to go this route for a carb application they can build a circuit to pickup of the VSS on the tranz if using a full manual 4l60e or 4l80e. A DRAC might also fit your needs and convert the 12V AC signal from the sensor to a 5V square wave most pics need.
It would be kewl if in time there were different mounting options for the motor as straight back may not work in all application. But a 90 degree drive might be the cats meow for some people.
Bruce
Before this thread started I was also looking into building something like this for my car, I already purchased the micro controller, looked at different pickup methods etc etc. They are one up on me here in the thread as I have been having problems finding a motor that should work at say 3-4 MPH at extended times. At very low speed, is were these motors are very inefficient and that can lead to heat problems, or plain just motors burning out etc.
If anyone is looking to go this route for a carb application they can build a circuit to pickup of the VSS on the tranz if using a full manual 4l60e or 4l80e. A DRAC might also fit your needs and convert the 12V AC signal from the sensor to a 5V square wave most pics need.
It would be kewl if in time there were different mounting options for the motor as straight back may not work in all application. But a 90 degree drive might be the cats meow for some people.
Bruce
02-29-2012, 07:33 AM
#107
I find it hard to believe anyone would complain at a 10-15mph problem when these speedometers shake until 30. It is just a design flaw in all GM speedometers until the middle 80's.
creating heat at low speeds? cant wait to meet the guy who is driving 5mph in his ls engine for long periods of time and needs a speedometer that works.
I agree to build it better, but any engineer will tell you that sometimes it is best to see someone elses work and make changes. The principle is there, vss signal to controller to motor.
creating heat at low speeds? cant wait to meet the guy who is driving 5mph in his ls engine for long periods of time and needs a speedometer that works.
I agree to build it better, but any engineer will tell you that sometimes it is best to see someone elses work and make changes. The principle is there, vss signal to controller to motor.
02-29-2012, 09:04 AM
#108
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I find it hard to believe anyone would complain at a 10-15mph problem when these speedometers shake until 30. It is just a design flaw in all GM speedometers until the middle 80's.
creating heat at low speeds? cant wait to meet the guy who is driving 5mph in his ls engine for long periods of time and needs a speedometer that works.
I agree to build it better, but any engineer will tell you that sometimes it is best to see someone elses work and make changes. The principle is there, vss signal to controller to motor.
creating heat at low speeds? cant wait to meet the guy who is driving 5mph in his ls engine for long periods of time and needs a speedometer that works.
I agree to build it better, but any engineer will tell you that sometimes it is best to see someone elses work and make changes. The principle is there, vss signal to controller to motor.
- quiet, small, and easy to install are the other design goals) Plus, half the fun is in the prototyping! We don't wan't to give you an overhauled cablex, we want to give you a better approach.
02-29-2012, 03:34 PM
#109
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No need to reverse engineer someone else's stuff, and here's why: the goal of the cablex is to drive the cable. Our goal is to drive the speedo. There is a difference (about a 75dB difference actually - quiet, small, and easy to install are the other design goals) Plus, half the fun is in the prototyping! We don't wan't to give you an overhauled cablex, we want to give you a better approach.
- quiet, small, and easy to install are the other design goals) Plus, half the fun is in the prototyping! We don't wan't to give you an overhauled cablex, we want to give you a better approach.
03-03-2012, 12:12 PM
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starting to think about all you carbeureted guys - if I make an analog input module I can conceivably take any analog VSS input from anything with a 40 tooth reluctor ring. No VSSB, DRAC, or ECM needed.
03-03-2012, 02:56 PM
#112
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You guys are Gods. Hopefully it would be idiot proof. Any ideas about the control box? I was thinking of two buttons to calibrate it; speed up, speed down to match the GPS speed so you could do it on the fly. I know you guys have something up your sleeve.
03-03-2012, 10:40 PM
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well the calibration function is still just ideas on paper, really. It will be a function of speedo sweep (in degrees, probably everything from 270° round gauges to 135° rectangular), and MPH scale (0-120, 0-160, etc) linked to specific motor rpms. It will have some sort of manual adjustment too, but not real sure yet how we'll implement that (I like the GPS match idea). Totally want to make that as brainless a task as possible.
03-06-2012, 09:09 PM
#116
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Small update, test speedo running perfectly, 40,591 miles. I did change the speed to about 85 mph, just because. Oh and we should be testing the prototype in a vehicle this weekend. Everybody keep their fingers crossed!
03-07-2012, 05:14 AM
#118
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This looks GREAT. I'm inching foward on my swap and keeping my fingers crossed that this is the answer to keeping a stock speedo. Please stay on and keep us posted.
You guys 