Hello,
I currently have a manual potentiometer that I want to replace by a digital potentiometer controlled from an arduino but I know much about potentiometers and I was wondering if this potentiometer could replace the actual one which is this one.
Thank you for your time.
We need to know what circuit it is in.
The manual one is 2W.
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I don't have many informations about the circuit, I'm trying to replace the dimmer from this power supply
My gut felling says use the existing manual pot in the circuit.
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Yes but I can't control it with the arduino?
That's correct.
That's just my gut talking since you have no other information on the circuit.
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Hi,
This is what the dimmer says s how to connect it.
Connection Instructions:
Red wire is positive and the black wire is negative, both are output connect to the LED; brown wire is positive and the blue wire is negative, both are input connect to the power supply.
I would not even trust the unit at all, when the seller knows nothing about AC or DC.
The dimmer pot, could be at any potential, even at mains potential.
Can you tell us your electronics, programming, arduino, hardware experience?
Thanks.. Tom.. 
Without knowing anything about the circuit the risk of electrocution means the only
answer we can give is 'no'.
Without opening it up and taking good photos there's nothing more to say really.
The AD5220 datasheet ( do you know what that is ?) states maximum current between pot terminals is +/- 20 mA. Vdd is 5V (7 max). The manual pot is 2 W. ( I = P/V = 2/5V = 0.400A. (400 mA)
This means the manual pot is rated for 400 mA while the digital pot is rated for 20 mA.
Conclusion: The digital pot CANNOT be used to replace the msnual pot. Thst manual pot is expensive. Such an exoensive pot would not have been chosen by the equipment manufacturer iwere it not for the fact that it can tollerate 400 mA.
Your post cannot be answered based on the information (or LACK THEREOF:ie. schematic of circuit) you presented, but based on what you did present, the answer is NO.
If this dimmer switch is on the wall in a house in the usual way then I go along with all the replies above.
However, if you were willing to think laterally and move it (or have a bigger pattress) you could rotate the existing pot with a servo or stepper motor using the Arduino. Always a bit risky and given that you seem a bit new at this game it might not be something you should undertake (now there's a word not to be used in this reply) as you are dealing with mains electricity.
But I mention it only as a bit of lateral thinking and not because it answers your original query.
Just suggestin'
@R_Bacon,
Look at power supply linked in Reply#2
I just purchased (cheap) on ebay some AD5220 digital pots. I have no need for them right now, but would just like to 'see' what happens when I apply terminal voltages outside the 'voltage supply' range.
So far, all I see in online sites is 'terminal voltages limited to supply voltage range'. Some sources say things like 'most digital potentiometers have terminal voltages limited to supply voltage range' (or something along those lines). But...... they never explain why.
Anyone out there got some decent details from manufacturers about the reason for the voltage limitation?
I assumed that the resistance was due to internal switching, such that the resistance between wiper and a terminal end would be independent of terminal voltage (unless of course some large enough voltages were applied to cause internal breakdown).
Anyway, if the internal switching does depend on those terminal voltages, then they should consider putting out Gen 2 digital potentiometers to bring us out of the dark ages. Anyway, would be nice if there's some explanations online about the reason for the voltage limitation. Otherwise, if no reasons exist, I can definitely see (and report on) what happens when my AD5220 devices arrive.
Anyone out there got some decent details from manufacturers about the reason for the voltage limitation?
Because they aren't designed that way. It's more expensive to make a digipot where the wiper terminals can be outside the supply limits of the digital logic.
The exact physical details don't really matter, just know that it is a physical difference in the circuit design.
Also, there are "Gen 2" chips that can have high voltage on the wipers. I've got an AD5290 that can take +/- 15V supply voltage and handle that voltage on all the supply terminals.
Problem for you is it cost 5 USD and only comes in a very hobbyist-unfriendly MSOP-10 package that is half the size of my pinky fingernail. It's nothing like the cheap Microchip digipots you can get 2 for a dollar in DIP packages.
Hey thanks jiggy! I'll order a couple of those AD5290 you mentioned to try out as well. Much appreciated.
[update] - just ordered a couple a moment ago (AD5290).
Thank you for all your answers, I will try to respond to some of them:
Many of you want more informations, I will ask the seller for the data sheet (but I doubt he is going to provide it), I can also open the plastic box which contains the dimmer and take up some measurements if it is useful.
TomGeorge:
Hi,
This is what the dimmer says s how to connect it.I would not even trust the unit at all, when the seller knows nothing about AC or DC.
The dimmer pot, could be at any potential, even at mains potential.
Can you tell us your electronics, programming, arduino, hardware experience?
Thanks.. Tom..
I'm good at programming and now I'm trying to interact with the real world, I have basic electronics knowledge.
Ralph_S_Bacon:
If this dimmer switch is on the wall in a house in the usual way then I go along with all the replies above.However, if you were willing to think laterally and move it (or have a bigger pattress) you could rotate the existing pot with a servo or stepper motor using the Arduino. Always a bit risky and given that you seem a bit new at this game it might not be something you should undertake (now there's a word not to be used in this reply) as you are dealing with mains electricity.
But I mention it only as a bit of lateral thinking and not because it answers your original query.
Just suggestin'
Yes, I thought about it as my backup plan but it's a bit tedious compared to a simple potentiometer.
The black " dimmer box" could be mounted on a sheet of G10 and the dimmer shaft coupled to a stepper motor with a shaft coupler.