Beginner with Arduino here, but trying to wrap my head around what I need to make my task work. I am trying to control an HVAC system that currently runs using a manual potentiometer (to adjust temperature).
I have measured the voltage across the terminals of the existing potentiometer at 2.35V
The datasheet for the existing potentiometer says it has a 0-1 kOhm range
It is a remote setpoint for a Siemens RWC62 temperature control module.
What I am trying to do is switch this setpoint from a manual rotating knob to an Arduino-controlled digipot. I feel like AD8402ARZ1 or AD5254BRUZ1 could've been good options but I don't have the soldering skills to attach them to a circuitboard, so I think those are out. Most 10 kOhm digipots seem to have 128 wiper points, so that means the 0-1kOhm adjustment range would only have a few steps, so that doesn't work. I've also seen many that seem to have VCC at 3V+, so does that mean they wouldn't even work with my 2.3V input voltage?
Appreciate any advice on what digipot I should get so I can start racking my brain about how to actually make this happen.
It looks relatively simple: the RWC62 has 2 terminals, to which the potentiometer is connected; according to the RWC62 manual, depending on what the readout across those terminals is, the RWC62 will set the temperature. When turned counterclockwise to 0, voltage across the terminals drops to 0; when turned to max, it rises to 2.3V. That seems to be the extent of what's happening in this particular setup.
10K would have steps that are too wide, though, I think, if there are 128 wiper points? But even if I find one - say the Adafruit DS3502, it says 2.5V-5.5V input voltage. Does this mean this will not work for my application since I'm measuring 2.3V at the most?
Across the green circles, also across the wires labelled "1" and "2".
The actual potentiometer in question is a Siemens BSG21.1. The Siemens datasheet for that does not mention anything other than it being a 0-1,000 Ohm potentiometer.
I did turn it, yes - counterclockwise to 0 would give 0V, and clockwise to max would give 2.3V. I'll be honest - I'm a little bit vague on the difference between a potentiometer and a variable resistor - I feel like all potentiometers are variable resistors and I think the third leg of a potentiometer can possibly be wired to one of the other legs, making it a 2-terminal connection... but I am clearly out of my league on this one.
I was suggested to look into digital potentiometers to replicate this functionality on Arduino, so that's why I've gone down this route of searching
Correct, just be sure the digipot is capable of outputting the needed current, might need a voltage follower op amp constant current driver down stream.
I see. Wouldn't it just take input voltage of 2.3V, reduce it depending on the setting of the wiper, and output whatever was left - and the RWC62 would read that and set temp accordingly? I feel like that's how it currently works.
