Hi Folks,
Currently looking to create a tank level display system using an ultrasonic sensor.
I cant use a float switch as the tank is 1.8m deep and float switches dont come in that size.

Was thinking of using a 4-20ma Ultrasound sensor and some sort of a panel mounted display.
That means I would have to scale the 4-20ma output into a 0-100 display. Does anyone know how to easily do this with electronic components rather than me using an arduino or other plc?

Or is there any other system out there you can think of that is easy to use and calculate tank level?
I cant use the household oil tank systems as they all mount on a 3 pin plug in your house. I have to wire in a panel mounted system.

Thanks for the help.
Cheers

 

If you think of it this way you have a striaght line graph with an offset in
the Y axis. Its slope is a gain, and offset is the value at x=0 of y.

So thats an opamp with G followed by an opamp subtractor to
remove the offset.

So in the loop you have a low valued R to convert V to I, amp it, then
subtract out the offset.

This is a quite easy problem with a UP, either programmed in Basic or C
language. An Atmel ATTINY or Cypress PSOC would be an easy implementation.

https://www.hackster.io/PSoC_Rocks/...ance-with-hcsr-04-and-cy8ckit-049-4200-db84e8

https://www.element14.com/community...ance-measurement-psoc-4-pioneer-kit-community

Or a couple of OpAmps, one for G, one for the offset problem. In fact
you might be able o do it all with one, a subtractor with gain.

http://www.dummies.com/education/sc...unique-inverting-op-amp-an-op-amp-subtractor/

Regards, Dana.

 

How about a sight glass? A red ping pong ball. And a magic marker.

 

You can buy 4-20mA to voltage converters or do you want to make you own?

 

Yes make your own. Look @ TI there is a cheap chips doing the job for you.

calculate is simple

formulae result % = (measured value - 4) * 100/16 ( scale 0-100%)

The first 4mA not used so value -4 leafs you a real value of 0-16mA
scale 0-100
16 should deliver 100%
real value * 100/16
test 12mA measured
12-4=8
8* 100/16 = 100/2 =50%

Picbuster