Are there potentiometers that can be adjusted through electronic input?
I am thinking about a project in which I would like to vary the power to an AC device but through touch membrane buttons rather then turning a knob or sliding a slider. I have thought about using a servo with Gear/Belt to do so, but was wondering if such total electronic version that exists for this.
Yes, they are called "digital potentiometers". Example
Be sure to read the data sheet carefully, as there are voltage and current limitations that must be observed.
I don't know any that could "vary the power to an AC device", and most people would not use a mechanical potentiometer for such a purpose.
Controlling an AC device would normally be done with a triac/SCR/thyristor, not a digital pot (which couldn't handle much power at all).
I am thinking of a way to control the motor for the air pump that creates bubbles in my hot-tub. Not the water jets, just the bubbler. It comes with a 110ac motor and your only option is on or off. I added an AC variable resistor and turning the knob works fine. However I am envisioning a control panel with buttons and readouts to control the hot tub functions. So you could for instance set the bubbles say from 0-10 and that value would display on an LED numeric display and the AC current to the bubbler would adjust based upon that value.
What you are probably using now is a light dimmer, those normally do have a pot but the actual power limiting is done through phase cutting.
Arduinos can do AC phase cutting as well with the help of some external hardware.
Noone mentioned it yet? 110 V + water = death! You should be very very careful what you are doing. Ideally find someone skilled to verify your circuit before truly using it.
I take safety lightly compared to other members but this is really dangerous.
I added an AC variable resistor
Please post a link to the product page or data sheet for this item.
I added an AC variable resistor
The only thing I know that fits that description is a [iurl=20 Amp Variac Transformer | Variable AC Power Supply | TDGC2 2D | Circuit Specialists Tier A%2FB%2FC%3A Bing%3A Shopping - US&msclkid=c69b3219f72b114a4e59520ddd8ef0dd]VARIAC[/iurl]
Ok, So the item I am using is actually just a dimmer (attached a pic).
I am concerned with safety, and realize it might just be better to trash my idea.
The motor of the 'bubbler' connects to the hot tub via a plastic tube with a flapper valve, so although it prevents water from backflowing, it is very possible for some water to make it back to the blower. but it would still need to collect in order tor reach the height of the motor.
That being said, the last thing I want to have happen is to come home to my family cooked like soup. So I am having second thoughts about my idea.
Use a stepper motor and a rubber belt to turn the pot.
My thought and just my thought is before doing anything I would look long at hard at the nameplate data on the actual pump. With an actual part number you can see if the motor can use varispeed and if yes, which method to use. What you linked to just looks to be a phase fired triac which is popular for smaller motors while a VFD (Variable Frequency Drive) is popular with larger motors. Unless the tub manufacturer suggest the modification I personally wouldn't bother doing it. However, your tub and your call.
Even if deemed practical you will need an interface to your uC (micro-controller) be it Arduino or other. Something like a horizontal or vertical scroll bar. Then an output to your motor speed control.
Ron
Note that not all AC motor types can have their speed controlled - if in any doubt don't
try to do this, some induction motors can stall and overheat if not fed their nominal
supply voltage.
mauiman808:
Are there potentiometers that can be adjusted through electronic input?
Definitely there is. It all depends on definition of electronic input too. Like you mentioned ----- it's possible to just physically couple a stepper motor or some other rotating device to an actual classical analog potentiometer dial. And the electronic input would be to make the stepper motor rotate to the correct spot (ie. turns the dial).
There are some devices that a manufacturer (or somebody) coined as 'digital potentiometer' ------ but the term is somewhat misleading. And at the moment appears to be no 'wiperless' digital devices that actually provides the same features as the classical wiper potentiometers. The devices that people call 'digital potentiometers' also have 1 or more of the pins being in the range of 5 volt ----- or something like that ----- while actual 'potentiometers' don't have such requirement.
Also - depending on what application it is ....... it may be a good idea to have regular potentiometer ------ where at least the dial stays in a particular position, and doesn't reset itself when we walk away, or the system gets unpowered and repowered.
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