Variable digital resistor???????

[ArcAngel2479]

I was trying to setup a new project, but rather than using a variable pot, I wanted to setup a digital setup with 20 settings, each setting being a different resistance.... controlled with an up button and a down button, also with an led display to display a range between -6 through +13, Any help would be apreciated .

If any clarification is needed, please reply...


BTW my electronics knowledge is minimal.........

 

[audioguru2]

Hi ArcAngel,
Welcome to our forum.
There is a Digital Pot project in our projects section. It uses an IC that steps a linear voltage divider from one end to the other end in 64 steps. It uses an up button and a down button. Before you use it, precautions are required to protect it from out-of-its-range voltages not mentioned in the article.
http://www.electronics-lab.com/projects/audio/033/index.html

Since your electronics experience is minimal, perhaps a kit is available for a digital voltmeter.

 

[ArcAngel2479]

Thanks for the reply, for some reason I couldn't get that post to come up during my searches... I apreciate it...

 

[ArcAngel2479]

After looking at the diagram and kinda deciphering it, I realized that it may not actually work in my application...


My intended use for it is to have 20 predetermined resistor values, set in line, to trick the PCM (computer) in my car to think it's colder/hotter via the IAT (Intake Air Temp) sensor on the car, hence advancing or retarding the timing of the car for Drag racing purposes.... I need to figure out the temp/timing advance tables, then setup them up in the following order -6, -5, -4, -3, -2, -1, 0, +1, etc. leading up to +13 degrees of timing advance.....

I figured a way to do via a rotary switch, but the one I found only allows for 12 settings..

Though it would be much easier/cooler to have it controlled via up/down buttons with an led display to show the current setting... so as not to blow up the engine

 

[MP1]

It would be easy with a microcontroller, but perhaps you could use the 4066 as the heart of your system.


MP

 

[audioguru2]

Hi ArcAngel,
Why doesn't your car's computer provide your required timing?
Maybe "so as not to blow up the engine"?
Just cross your fingers and give it a shot of nitro!

I wish I could trick my car's computer so it doesn't turn off the engine when I am passing and a big truck is coming at me.
The car's manufacturer and my government say the governor is for "safety", so as not to blow up the tires. ;D

 

[ArcAngel2479]

microcontroller? 4066?


and audioguru, the governor came off long ago, the car started off as a low 15 sec. supercharged V6, at it's current state, it ended last season at mid 12's, mainly do to improper tuning in the computer which will be fixed this season.. But with my current mods on the car, including a water to air intercooler for the S/C, cam, headers, etc. , I should be able to advance the timing, unlocking HP, without blowing anything up...

BTW Nitrous = Cheater Gas

I hope to end this upcoming season in the mid 11's or better, thus allowing me to not only take out stock vette's, but hang with the modded ones as well


Any elaboration on the microcontroller, or 4066 would be apreciated, I'm great at following diagrams and such, it's just building the circuits that I can't do... Thanks...

 

[audioguru2]

Hi ArcAngel,
I didn't want you to cheat and use nitro in the engine. Just spray it on the intercooler to allow the engine to breath cool, dense compressed air. Better cooling than water. I hope your fuel pressure and flow rate is high enough to match it. You know what running lean will do.

I drove a turbo for years. I bought it for my wifey but hardly let her have it. She stepped on it when the light turned green then asked, "Why is everyone back there?". Me too. Lots of fun.

My son has a AWD Eagle Talon with a dinky but powerful 2l turbo'd motor. He is aiming for the low 9's and nearly 160mph like this one:

[attachment deleted by admin]

 

[ArcAngel2479]

gotcha on the nitro spray.. one of my club members actually tried something like this on his with no real benefit. though he did CO2 to spray the front mount... it didn't really cool the temps, since it's a water to air setup.. not air to air......

fuel pump has been upgraded, and the pump wiring upgraded, larger injectors, and an air fuel calibrator which can be seen custom mounted here ---> http://www.tristategm.com/nymcgp/member/ArcAngel%20Folder/AFC2done.JPG

I know all to well what running lean will do as my friend ran his car prior to tuning in some new mods, only to run lean and blow 3 pistons, as well as blow new headgaskets....

turbo cars are fun, as are the talon AWD, those have a nice take off... 9's would be great,

But in my case, 9's are far off, being a 3600 car, with FWD doesn't help in that department.. though some members in my forum run 10's with theirs, I'm more of a budget minded racer, so I try and make my own products/ mods when possible....

here's a pic of the car just in case you were curious....

 

[audioguru2]

Ah, ha. A nice clean Grand Prix GTP. I nearly got one. Many guys change the pulley on the supercharger. Is that a speeding ticket in its windshield? ;D
I thought you might have a vintage Fiero. They were also nice but you needed to carry a fire-extinguisher on your back!

Instead of tricking the car's computer, have you considered commanding it with a Palm Pilot or laptop?

 

[ArcAngel2479]

Actually, I have ordered a tuning program for my pcm, to fix the issues I had last season, I would be able to command the timing, but being my daily driver, I wanted to be able to change it on command withing the car, without the need for a laptop....

I scan the car via LS1 M program on my palm.. this allows me to fine tune the A/F ratio..

 

[Dazza]

ArcAngel2479, check this out(http://www.autospeed.com/cgi-bin/browse.cgi?category=4334&sc_add=100770004&amp the programmable ignition timing module, may make the purchase worthwhile .

 

[ArcAngel2479]

ArcAngel2479, check this out(http://www.autospeed.com/cgi-bin/browse.cgi?category=4334&sc_add=100770004&amp the programmable ignition timing module, may make the purchase worthwhile .

This programmable ignition timing module used in conjunction with our high energy ignition module KC-5247 allows you to program timing of engines with points, Hall effect or reluctor distributors



that's what it states on there, I have ignition coils, and timing is controlled via the onboard PCM, so that wouldn't work...



It looks as though I may just have to build this thing out of this rotary switch, no digital for me ..... I will just need the rotary switch, 20 resistors, and some wire...

 

[jpp412]

You can just buy the digital pot - check out digikey.