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Convert standard gauges to rally pack |
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FuzzFace2 
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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 Posted: Jun/13/2014 at 9:08am |
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I could be wrong but when he first posted this I Goggled Arduino and it looked like a type of program language that you could use any sender, after knowing the range or sweep, as the in-put to the program and then have an out-put to work/move the motors to operate the needles. If I have that right he could use any sender with a sweep (not on/off like a light would use) that fits the opening needed and write the program needed to move the motor as needed. It is something like Speed Hut uses for the fuel gauge. You give them the range of the sender and then program the gauge to it. You then “fine tune” it when you install the gauge by setting/programing it to the empty level and then full level IIRC. Been a wile since I went over the sheets. Did I get that right Dan? Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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304-dude
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Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Posted: Jun/13/2014 at 9:30am |
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Not to steal the show... just adding what I did a while back, using just the factory Tic Tac Toc only and modding the speedo for a magnetic pickup at the drive shaft, and modding a factory gauge cluster to read in voltage instead of alternator.
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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aerovalyou
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Joined: Jan/09/2014 Location: NY Status: Offline Points: 7 |
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Posted: Jun/13/2014 at 9:48am |
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Dave, you're quite right. The Arduino has the hardware to accept a 0-3.3v (0-5V for other versions of Arduino) signal, and I write a little code to drive the gauges to where I want them. What I'm doing with the senders is using the original senders for fuel and temp, I picked up the cheapest quality oil sender on ebay, a simple voltage divider for the voltmeter (2 resistors in series with a center tap) and I will be using the tachometer input circuit that Megasquirt uses for their boards. I've developed a simple signal conditioning circuit that allows me to tune the gain and offset for each sensor and scale the output to a 0V to 3.3V scale for the Arduino. I have an excel spreadsheet that lets me put in the max and min resistance for the sensor (the AMC resistances are in the TSM), and calculates all the resistor values for the circuit. Here's a picture of the circuit:
http://s899.photobucket.com/user/aerovalyou/media/SignalSonditioner.png. -  I wouldn't use that circuit just yet: I've simulated it, but haven't built it for real yet. Once I know it actually works I can provide anyone who wants it my spreadsheet for the resistors, and you could use ANY resistance based sensor to generate a 0V - XV signal. 304-Dude, that looks great, and even harder to spot it's not an original rally pack! I wanted to go that route, but I couldn't find a rally pack, or even parts to make one, that wasn't REALLY expensive. For my major components, the Arduino was $40 (and a Christmas present!), the gauge motors were $15 each on ePay, the stepper drivers were $10 each, and the GPS for the speedo was $15. I've probably got another $50 in miscellaneous parts, so all told the whole cluster cost me $250, and I spread that over a few months. I noticed you're missing the cap for your speedo needle, I think I have my original needle and would be happy to send it yo you if you'd like it.
Edited by aerovalyou - Jun/13/2014 at 10:02am |
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Jun/13/2014 at 10:07am |
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Dan, One of the things I was told of the stock AMC fuel senders is they are not linear from empty resistance to full resistance. I do not know if true or not as I never looked that deep into it. I gave SH gauges the empty/half(what I thought it would be)/full resistance to program into the gauge and hope the rest would fall into place close enough to be OK. As long as it is good at/around empty so I don’t run out of fuel I am OK with it. I have had the gauges for years but the car has not been on the road yet so cant say if good or not. So you may want to check out that stock fuel sender to see what you get. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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aerovalyou
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Joined: Jan/09/2014 Location: NY Status: Offline Points: 7 |
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Posted: Jun/13/2014 at 10:35am |
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Dave,
You're right, in fact most resistance based sensors are non-linear, even in modern cars. Here is the Javelin's coolant temp sender curve, with my curve fit. The funny thing is that the old AMC gauges are linear. If you've ever opened one of those fuel/temp gauges up, it's ridiculously simple. The current through the gauge and sender heats up a bimetal strip, and that strip heating moves the needle. Our choke heater is more complex! The great thing about Arduino is that you can write the curve fit into the code, and get a sensor that is if anything too accurate. In fact I have to do something in the code to slow down the needle, because if I don't it will always move at full speed, and as gas sloshes around in the tank the needle will bounce around :) http://s899.photobucket.com/user/aerovalyou/media/CTSCurve2.png. -
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304-dude
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Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Posted: Jun/13/2014 at 10:50am |
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It has been a long time... in keeping some accuracy heat will also play a factor.
I am not sure, but using a UJT or Fet pre-amp circuilt may help |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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FuzzFace2
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Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Posted: Jun/13/2014 at 1:00pm |
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Dan, I should have known you would have it all covered. I was only told of the fuel sender and why I wanted to send it on.
Only porgraming I did years ago was on a Johnson Controls HVAC panel that did chiller output and 3 AHU's (air handling unit) temp output. On the AHU's it was heck to set up because the air flow would go up & down from a 2nd system (not tied into the JC unit) that the recovery would be good for 1 air flow speed but not the other and the other way around.
So I know a little about slowing down or speeding up the output of a device to work right, Oh what fun that was.
Now when you guys start talking about the fancy electronics you loose me. It is still cool to see how you are doing this. Keep it coming. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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aerovalyou
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Joined: Jan/09/2014 Location: NY Status: Offline Points: 7 |
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Posted: Jun/13/2014 at 1:30pm |
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Sounds like a tricky controls problem. When it comes to this stuff I have a bit of an advantage: I run a wind turbine testing lab at a college, and was a helicopter avionics and electrical tech for 11 years in the Army before that. So a LOT of what I do is instrumentation. I will admit this is my first experience with Arduino, and I usually buy signal conditioners, not design them. The circuit above is the most complex one I've ever designed, and my experience with electronics tells me that until it's soldered up on a board and tested, I really have no idea if it's going to do what I think it will
 Hopefully I will have a positive report in a week or so.
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MikeKaldenberg
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Joined: Jan/01/2015 Location: Central Iowa Status: Offline Points: 58 |
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Posted: Jan/19/2015 at 4:11pm |
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Inspiring! Great progress.
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White70JavelinSST wrote: