water guage working on water pressure

[simonfraser]

so you have a water tank and want a matching round VDO like display to show what's in the tank
yes henderson do a working product, but i dont like the gauges, call me fussy

the VDO type displays work on 0 - 180 ohms, its basically a resistance meter, zero = empty 180 = full
this is fine if you can get to the top of your tank and fit a sender, i can't, well not without major surgery

so i rigged up one of these, it needs a 5 V input: (any USB outlet will supply that)

file:///C:/Users/simon/Google%20Drive/Zwollywood/Manuals%20&%20Instructions/Water%20pressure%20guage%20analouge.pdf

this one suited my purposes:

785-HSCSANN001PGAA5
Board Mount Pressure Sensors SIP,Single Ax Barbed Gage, 5V

the barbed end of the pressure sensor is quite small, 3.7mm external, plenty of silicone tubing for sale on ebay
you just have to sort an adaptor to your 14mm water pipe, various bits of tubing and sikkaflex did the job

get the analouge version and it sends out a voltage linear proportional to the pressure in the water supply
i happened to have a tank of a suitable height for one of the sensors, but i guess you could extend the supply downwards a bit furter to create a higher head of water if needed, the display wont quite match the tank then of course

so now you have a varying voltage:

https://www.ebay.com/itm/262975817155?ViewItem=&item=262975817155

this converts the voltage to resistance, which will drive your VDO or similar display


standing back for some one to show me a simpler way

 

[vas]

I've done the same in a slightly more convoluted way and got NMEA2000 output passed on to the bus, so now my Garmins can show fresh water tank as well as diesel tank level.
I bought the same sensor but in a kit by a company I've used their domotic stuff before for my house, so it was a complete kit accepting non stabilised 12V supply (perfect for NMEA2000 bus voltage) and outputs 0-5V.
Bought a teensy, a 2euro chip that does the N2K can bus conversion and a few bits and bobs, presto!
Keep in mind even this way, I had discrepancy between USB power and N2K supply, so sensor is too sensitive to ground and level of power. Don't know how it will perform with your setup.

Summing up, approach is fine, result is okayish without some form of computing doing the exact conversions (mind the converter you're thinking of is more expensive than the arduino and you can use that for a dozen other things...)
No time to search now, but I've posted I think here in the PBO on a couple of NMEA2000 threads, or else in mobo.

cheers

V.