Get Design Help for Custom Indicator & LED Bar with Pressure Sensor Readout

[vadslram]

I'm real lame at design but I enjoy trying so now I'm actually going to ask for help.
I've been trying to make a custom indicator for my truck to make it more tech cool. I want to take two values from pressure sensors and output it to a digital readout of one sensor and a cascading LED bar for the difference between the two sensors. All this in a package about 2"x2"x4" I want to use it as a filter health check.
It should be fairly simple but I'm just not getting it.

Anybody out there got some ideas?

 

[vadslram]

Oh yeah, I'd be willing to pay for plans, in cash or barter. (pII laptops, GPS receiver etc.)

 

[berkeman]

Sounds like you should look into using simple microntrollers for your projects. They'll give you lots of flexibility in processing your sensor data, and coming up with really cool displays. Start by looking at the Basic Stamp modules and the accessories that you can get with them:

http://www.parallax.com/

Also, if you are just starting out in electronics, I'd recommend that you get a copy of "The Art of Electronics" by Horowitz & Hill, and read it cover-to-cover. Have fun!

 

[jsaxton]

Winter break is coming up for me in a couple days. If you'd like to give me some more details, I could look into it (I'm not making any sort of commitment here).

AIM: jsaxton14

 

[vadslram]

I'll have to set up AIM..but for now.
I want to take feeds from two standard automotive 12vdc neg ground variable resistance pressure sensors (they are the largest failure possibility so they should be generic and replacable)
One will be set to the prefilter side, the other to the post filter side.
In the cab there is a 2" x 2.5" cubby on the dash. The prefilter input should read out to an LED display for 0 - 18lbs (standard gauge type stuff)
then next to the digital should be a cascading LED bar that will display the delta of sender 1 and 2. Probably 5 or 6 LEDs (~2 green 2 yellow 2 red). That will light on 2 lb differences.
So in theory if your reading 15 on the readout and 3 LEDs are lit then youve got 9 lbs out of the filter.
Reasoning for this gauge is Dodge diesel pickups are REAL sensitive to low fuel pressure to the injector pump, too long at low pressure and you need to replace a $1400 pump. Yes I had to do that and after labor and towing it cost $3k

 

[dlgoff]

I'll have to set up AIM..but for now.
I want to take feeds from two standard automotive 12vdc neg ground variable resistance pressure sensors (they are the largest failure possibility so they should be generic and replacable)
One will be set to the prefilter side, the other to the post filter side.
In the cab there is a 2" x 2.5" cubby on the dash. The prefilter input should read out to an LED display for 0 - 18lbs (standard gauge type stuff)
then next to the digital should be a cascading LED bar that will display the delta of sender 1 and 2. Probably 5 or 6 LEDs (~2 green 2 yellow 2 red). That will light on 2 lb differences.
So in theory if your reading 15 on the readout and 3 LEDs are lit then youve got 9 lbs out of the filter.
Reasoning for this gauge is Dodge diesel pickups are REAL sensitive to low fuel pressure to the injector pump, too long at low pressure and you need to replace a $1400 pump. Yes I had to do that and after labor and towing it cost $3k

You might want to take a look at http://www.omega.com/pressure/psc.html" .

Regards

 

[vadslram]

Yes I searched that site. Couldn't afford $629 ea for two transducers. They are a little more sensitive then I need and they still didn't have a differential readout that I could mod to fit in the cab.
(edit) I just found a $55 diferential unit there, not sure why I missed it a couple of weeks ago. Thnx.
Still not a readout though, that's going to have to be custom.
(edit2) all their differential units are gas pressure only, petro fluids will ruin them :(

 

[dlgoff]

...Still not a readout though, that's going to have to be custom.

You could purchase a cheep "ready built" display ready for a voltage input.

...all their differential units are gas pressure only, petro fluids will ruin them :(

There are such things (if I remember the correct term) as stubs. They screw in between the source and the transducer; they are designed to isolate.

Regards

edit: They're called https://www.physicsforums.com/showthread.php?p=863796&posted=1#post863796".

 

[vadslram]

The feedback I got through Omega is that the snubbers are just to even out pressure spikes not to isolate fluids. They would still allow the diesel to reach (and ruin) the differential units.

 

[dlgoff]

The feedback I got through Omega is that the snubbers are just to even out pressure spikes not to isolate fluids. They would still allow the diesel to reach (and ruin) the differential units.

Sorry for the wrong link in my previous post. The correct one is http://www.omega.com/ppt/pptsc.asp?ref=PS_SNUBBERS&Nav=prec02". The first two listed are for oils. They should work for diesel oils, I think.

Regards

 

[vadslram]

That's what I thought until greg sent me an email saying "The snubber has a porous metal disc " then he said I could use it but all warrantees would be void.

 

[dlgoff]

I say try it. But that's me.