Digital: fuel pressure gage; boost gage

[Don.F.Broadus at ucm.com]

The Scale no doubt uses a 3 wire load cell. The load cell consist of 2
resistors in a balanced bridge configuration. When a force
is placed on the load cell the resistance changes and unbalances the bridge
creating an offset voltage that is scaled to read
pounds. I tried to reverse engineer the scale I had but didn't have to much
luck. It was a LCD display type and hard to trace out.
If you find a transducer with 0-5 volts or 4-20 Ma a panel voltmeter with
the correct scaling resistors would be all you would need.
If the transducer you find is a 4 wire bridge then you will need an
instrumentation amp and a panel meter. The fact that you are wanting to
measure Gasoline pressure will make vendors very nervous. Autometer has an
isolated system that uses a rubber
diaphragm to isolate the gas liquid. A gauge on the other side of the
diaphragm is responding to air pressure. So I would see
how much the isolator is and  find a pressure transducer and a volt meter.
 
Don     

> -----Original Message-----
> From:	Clarence Wood [SMTP:clarencewood at centuryinter.net]
> Sent:	Saturday, February 06, 1999 5:01 PM
> To:	diy_efi at efi332.eng.ohio-state.edu
> Subject:	Digital: fuel pressure gage; boost gage
> 
>   I have been playing with an idea for some time and today my wife caught
> me looking, "looking in a suspicious way", at our digital scale.  Having
> seen me look at things in that manner before, she challenged me to prove
> to her that its dismantling could in some way, be justified.  Since I
> bought the scale at a yard sale for $1.00, I argued, it was mine to do
> with as I pleased.  Well, she batted her beautiful green eyes and
> scrunched up real close to me and, well, I need some help on this one.
>   Is it possible to use the pressure sensing device in a digital scale to
> build such things as an electronic fuel pressure gage, or an electronic
> boost gage, or a boost control?
>   
> 
> Clarence 
> IZCC #3426
>  1982 280ZX Turbo GL
>  1966 El Camino
>  1982 Yamaha Maxim XJ-1101J Motorcycle
>  1975 Honda CB750 SS (black engine)
>  1986 Snapper Comet lawn mower
> Clarence Wood
> Software&Such...
> clarencewood at centuryinter.net
> Savannah, TN.