Hey... How much current can I draw off of the "radio" port in the fuse block? I'm not really sure how much I need... Enough to powerup to 10 LED's, and a LM3915... Or, are there any other good +5v to +12v SWITCHED sources in the dash anywhere?

Tim, what did you hook your TPS LED thingy up to? And where did you stuff the circuit board? The documentation I've found an the LM3915 say to keep the LED's <= 6" from the chip if at all possible, and from what I see, that's going to be hard to do...

Thanks,
-Tesla

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91 T/A 305 tpi SD
STB, Airfoil, Hooker cat-back, pseudo-cold air to K&N, Accel coil, !cat, !smog pump.
The Wankel Rotary Engine - The replacement for displacement.

 

The orange accessory wire (battery power) at the radio is on a 20 ampere fuse, and the yellow ignition power wire at the radio is on a 10 ampere fuse - either plenty for that application. There are some +5 volt references driven from the ECM, but I would not use those to power any digital circuitry. I put the controller box next to the ECM & used the ignition power source to the ECM to power the module. You are right - the LEDs are much further than 6" from the bargraph display driver. Use a large capacitor (2500 uf) at the module, and use 18 ga wire to run power to the module. I connected the TPS input to the TPS input to the ECM (+ is dark blue pin F13, - is black pin B5). The O2 bargraph is connected to the O2 input to the ECM (+ is purple pin E14, - is tan pin E15).

Tim

 

The capacitor.... Where should it go? <a href="http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM3915.pdf">http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM3915.pdf</A> (page 2) leads me to believe it would go...er..from the + side of the LED's to ground? My design is basically what's on that .pdf, only pin 4 is not grounded directly on mine...but to a pot, so I can adjust the bottom level.. Also, I haven't tried the capacitor before...it just worked fine when i had the LED's right next to the chip..

Also, is there any way to fix how the LED's get dimmer when more are lit (page 8 of the pdf)? Perhaps the cap will help a little...

I think I'm going to mount the board up where my head unit is, and put the LED's on top of the little plastic thing that my fog light is mounted on.. I think I can keep the wires VERY short that way....

Ah! I was about to run a wire from the tps sensor itself thru the firewall! Off the ECM will be much easier!

Thanks!
-Tesla

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91 T/A 305 tpi SD
STB, Airfoil, Hooker cat-back, pseudo-cold air to K&N, Accel coil, !cat, !smog pump.
The Wankel Rotary Engine - The replacement for displacement.

 

The LEDs should not get dimmer as the bargraph reading increases. I did a complete design for a TPS and O2 bargraph that I'll post.

Tim

 

Tesla, I E-mailed the schematic to you.

Tim

 

Tim, could you e-mail me the schematic to me also?


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup.

 

wouldn't you know, I already had soldered it by the time I checked my mail.. Hmm..I need to work on my soldering skills!

Anyway, mine looks something like:


(please excuse the drawing... It's *REAL* hard to draw a schematic in a paint program)

The main difference between mine and yours seems to lie in pins 6,7, and 8.. I don't need any of that A/C cutoff stuff, and I had just used <a href="http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM3915.pdf">http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM3915.pdf</A> as a reference (page 2)...

It works... It's mounted up in the car... But, it's got issues... Mainly, I have *REAL* bad fadeout.. my 1-5 led's are green, and 6-10 are red... by the time the second or so red LED is lit, you can barely see the green... if it's daylight, you can't see them at all!

Also, I'm getting some flicker... My ECM is way up in the door panel.. There this like 1.5"x2" hole in the metal plate that the cable goes thru, but that's too small to get the ECM out of. I ended up just running a wire from the tps itself back thru the firewall..

The flicker is proportional to engine speed.. Right now, I'm blaming it on the fact that at one point, my wire is in parallel with a plug wire! But, do yours flicker? Sould I perhaps just build a filter for it?

Thanks for all your help! This is just way too cool!

-Tesla

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91 T/A 305 tpi SD
STB, Airfoil, Hooker cat-back, pseudo-cold air to K&N, Accel coil, !cat, !smog pump.
The Wankel Rotary Engine - The replacement for displacement.

 

No flicker or fade - maybe you could try the high brighness (low current draw) LEDs or LED bargraps available from Digikey - they may help solve the oscillation problem caused by the ground shift at the comparator ladder network as the currend draw increases when the LEDs illuminate.

John, I'll send it to you on Monday....

Tim