10v

Projects General Guidance
1

Hi all

for my next project i want to control the temperature of a boiler remotely to do this i need to be able to supply the boiler with voltage ranging from 0v-10v which will range the boiler from 0c-100c.

what would be the easiest way for me to do this?

2

Please provide some details on the boiler. Is it a DC device? What current does it draw?

I would say use a transistor, but we need more details to determine which one

3

Are you completely sure that the easiest solution is what you're after? You can't use just a transistor as they're quite unstable wrt temperature (ambient). And water boils at 100 degrees. Boom?

And what TimMJN sez...

4

I have a feeling the Op wants to generate a 0-10v signal for the boiler control.

5

yes id need it to be stable and consistent voltage that can be adjusted remotely to suite.

there are many safety devices both mechanical and electrical to stop the "boom"

my main aim is to use a gsm shield and the cloud to remotely view temperatures and pressures within a temporary boiler trailer. if cant achieve stable voltages to control the temp its not too much of a bother i just thought it would be a nice addition.

6

Good.

Therefore:-

  • I'd go with either one of those Arduino's that features an inbuilt digital to analogue converter (DAC), or use an external serial DAC (8/10 bits?).
  • Smooth output with a small RC network before feeding an op amp to boost output to the full 10V.
  • RC smooth again.
  • If you really want to heat at 1 degree above 0 (10 mV resolution), I'd recommend dual +/- 15V supplies to the op amp. Use an off the shelf DC-DC converter + additional LRC filters for better smoothing. Perhaps add some indicator LEDs/resistors to load up the outputs as some converters have very poor regulation at small % loadings.
  • If accuracy is important, I'd set op amp gain with the appropriate 1% resistor combination, then add a smallish 20 turn trimmer pot. That will allow you to set range exactly for 10V using your Fluke.
  • Signal will be rock solid and pretty much temperature invariant.
  • Excluding the power supply, the circuity should fit onto a custom shield made with EDA software like KiCad.
  • Even on Uno real estate.
  • Order PCBs from some fab in China.
  • Stay warm

Does that cover it?

PS. Allow for a small 2 line serial LCD as an info/diagnostics panel.

PPS. Look up 2 stage PID temperature control as a future upgrade.

7

really appreciate the advice thanks COSSOFT ill look into all this.

plan is to have 4 lcd displays within the panel to display temps of various circuits,runa dn fault LED's for easy viewing.

and hopefully all viewable by myself on the cloud so i can see what each heating trailer is doing.