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Trip Computer Plan

XJ 6 Series III

Trip Computer modifications for Lumped cars

Without Computer Control,

.......A work in progress.......

This is the intellectual property of Mark Chiampi,

And as such, it remains his property.

He has permitted it's publication to this site, for the personal use of Jag-Lovers membership. It is NOT to be reproduced, in whole or in part, without his consent, in writing. The membership of, is permitted to use this material for construction of the unit, ONLY, for their personal, and private use. It is not to be reproduced in any form, electronic, or otherwise, for the financial gain of any third party, business, or other endeavor.

It is NOT permissable, to copy, print, or otherwise distribute, except as noted above.

The Plan, is to make fuel mileage function operational (editor) .

Mark Champi, writes:

Ok, you asked for it:

This is what I've got.

The schematic shown is a working test circuit that will drive the Jaguar trip computer. To make the unit really "work" the trip computer needs to have the frequency change (basically in regards to speed), and the duration must change based on how hard the engine is pulling (what kind of load). Obviously, you use more gas going up hill than down hill at the same speed.

So, another lister, allowed a fuel-metering device to create the pulses for the timing circuit. It was installed, and made a fully operational, working prototype.

The working prototype was accurate to within 5% and the only problem experienced was the 5 volt regulator kept burning out. The solution is to try isolating the regulator with a filtering capacitor on the +12V in, or to use diode(s) if needed.

The Fuel metering device used was a fuel transducer that is placed into the fuel line at the carburetor. It looks like a little paddle-wheel that spins around and outputs electronic pulses. It takes 12V in and outputs a frequency. The unit used was a Floscan P/N 264-905-08 and it cost $95.00.

Now is the GUESS part, on my part- I expect the wire coming from the Floscan transducer was connected to pin 2 (trigger) on IC555 in place of R2. Without tinkering with one-I can't say for sure.

For the technogeeks out there-the pin outs for the IC555 are as follows:

Pin 1 Ground
Pin 2 Trigger
Pin 3 Output
Pin 4 Reset
Pin 5 Var. threshold reference (Not Used)
Pin 6 Threshold
Pin 7 Discharge
Pin 8 +5v to +14v

I hope this is enough information to get a brave soul to finish out this project. I have had a lot of requests to get this info. out, and I would love to get around to finishing it up on my own car - But, I don't have enough hours in the day!!

Please let me know if you get this working…. and if you aren't brave…. keep waiting and eventually I'll finish it! Keep Lumping!!

Mark Chiampi 4/20/00

In addition to Marks sketch, I have included a plan for use of a PC Board, with layout etc.

Charlie .

Update 5/18/00

Inspired by Marks work, I have made a test circuit box,

following his schematic. Photos of work in progress, below




Total parts cost so far: under $5.00

2 ea 10K ohm potentiometers, Radio Shack# 271-1721

1 ea 0.47 mfd electrolytic capacitor (radial lead)

1 ea 0.01 mfd metalized film capacitor Radio Shack# 272-1051

1 ea 8 pin low profile socket Radio Shack# 276-1995a (pkg of 2)

1 ea experimenters PC board

one project box, and hookup wire,(which I had).

Next step Locate the Floscan P/N 264-905-08, and voltage regulator.






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