Control Motor With Optical Sensor

Thread Starter

amillson

Joined Mar 14, 2021
11
Hi, I'm a beginner with electronics but am excited to be doing a hands on project. I'm trying to build a small water pump that will be controlled by an optical liquid level switch. I have the motor, a Rule/Xylem Inline iL200 that requires a DC 12V 2.8A power supply (https://www.xylem.com/en-tj/brands/rule/rule-products/slimline-pumps/). I have a couple of questions:
1. I've found an AC 120V input, DC 12V 3.0A output power supply, but can't find any power supplies with 2.8A output. Will the 3.0A output be compatible with the pump's 2.8A motor?
2. I'm looking at using a sensor switch such as the SMD Fluid Controls OS5 (https://www.fluidswitch.com/wp-content/uploads/sites/2/2020/05/Basic-Optical-Switch-OS5.pdf). The idea is for the water pump to turn on when the optical liquid level switch detects water, and then turn off when water is no longer detected.
I'm not sure if another component such as a solid state switch or mosfet is required. Any help would be greatly appreciated, thanks.
 

Yaakov

Joined Jan 27, 2019
3,489
Hi, I'm a beginner with electronics but am excited to be doing a hands on project. I'm trying to build a small water pump that will be controlled by an optical liquid level switch. I have the motor, a Rule/Xylem Inline iL200 that requires a DC 12V 2.8A power supply (https://www.xylem.com/en-tj/brands/rule/rule-products/slimline-pumps/). I have a couple of questions:
1. I've found an AC 120V input, DC 12V 3.0A output power supply, but can't find any power supplies with 2.8A output. Will the 3.0A output be compatible with the pump's 2.8A motor?
2. I'm looking at using a sensor switch such as the SMD Fluid Controls OS5 (https://www.fluidswitch.com/wp-content/uploads/sites/2/2020/05/Basic-Optical-Switch-OS5.pdf). The idea is for the water pump to turn on when the optical liquid level switch detects water, and then turn off when water is no longer detected.
I'm not sure if another component such as a solid state switch or mosfet is required. Any help would be greatly appreciated, thanks.
As long as the supply is at least 2.8A it will work. The motor will not draw more current that it needs. 3A is probably idea but you should make sure there is a fuse or breaker to protect the supply from a stall or other overcurrent event.

You will need a circuit to handle the motor. That sensor can't switch the motor directly. You will also need to ensure there is hysteresis in the control circuit to prevent fast cycling. That is, it can't turn off as soon as the sensor detects it's pumped down if it refills fast enough to cause the motor to rapidly restart when the sensor sees the liquid again.
 

BobTPH

Joined Jun 5, 2013
3,658
Actually, a 2.8A motor will require a supply larger than the 3A one you found. 2.8A is the running current, motors need much mor, about 2 to 3 times their running current to start.

A 5A supply might work, but not guaranteed.

Bob
 

Thread Starter

amillson

Joined Mar 14, 2021
11
Thanks very much for your response. Can you recommend a circuit for this application, or the type of circuit and the parameters required? I don't know where to begin. I'm looking for a miniature circuit that could be placed in the pump housing that I am designing for rapid prototyping.
 

Bernard

Joined Aug 7, 2008
5,788
A 5 A supply is a bare minimum but probably will work with a little help. My 12 V supply is rated for 4 A so it would shut down when trying to start a 2 A motor. Adding a 2 ohm resistor in series with motors 1 ohm resistance allowed motor to start. After starting R was shorted. This was covered in a semi recent post but my memory only goes back about a month.
 

Thread Starter

amillson

Joined Mar 14, 2021
11
As long as the supply is at least 2.8A it will work. The motor will not draw more current that it needs. 3A is probably idea but you should make sure there is a fuse or breaker to protect the supply from a stall or other overcurrent event.

You will need a circuit to handle the motor. That sensor can't switch the motor directly. You will also need to ensure there is hysteresis in the control circuit to prevent fast cycling. That is, it can't turn off as soon as the sensor detects it's pumped down if it refills fast enough to cause the motor to rapidly restart when the sensor sees the liquid again.
Hi Yaakov, thanks very much for your response. Can you recommend a circuit for this application, or the type of circuit and the parameters required? I don't know where to begin. I'm looking for a miniature circuit that could be placed in the pump housing that I am designing for rapid prototyping.
 

Yaakov

Joined Jan 27, 2019
3,489
Hi Yaakov, thanks very much for your response. Can you recommend a circuit for this application, or the type of circuit and the parameters required? I don't know where to begin. I'm looking for a miniature circuit that could be placed in the pump housing that I am designing for rapid prototyping.
I can't provide a circuit but I can tell you that power handling device(s) to deal with the pump current will not be miniature. Usually there are many offers of specific circuits. With some luck, a regular doodler of circuits will pop up with ideas.
 

sghioto

Joined Dec 31, 2017
2,394
Here's a version using two sensors to provide a HIGH and LOW trip point.
The capacitor C1 may or not be required. It's job is to allow the pump to run for a few additional seconds after the LOW level sensor has deactivated.
1615827915158.png
 

Thread Starter

amillson

Joined Mar 14, 2021
11
Here's a version using two sensors to provide a HIGH and LOW trip point.
The capacitor C1 may or not be required. It's job is to allow the pump to run for a few additional seconds after the LOW level sensor has deactivated.
View attachment 232790
Thank you very much sghioto! This application is a scavenger pump in a very confined space. So the control system is binary; water or no water. There isn't enough space to measure high or low levels. If you could modify the diagram it would be really appreciated. Thanks.
 

Thread Starter

amillson

Joined Mar 14, 2021
11
Since I don't know the start up current I assuming a 10 amp supply will be sufficient.
The specs sheet recommends a car or boat battery.
[/QUOTE
The plan is to plug it into a 120V 15A wall plug, using a transformer with 12V output, current TBD. Do you see any issues with that? Thanks.
 

MaxHeadRoom

Joined Jul 18, 2013
23,618
The site mentions 2.8 amps max, which I would not expect any difference for a pump dia of only 36mm.
You most likely can get away with just a full wave bridge with no other device, cap etc needed.
 

BobaMosfet

Joined Jul 1, 2009
1,848
Hi, I'm a beginner with electronics but am excited to be doing a hands on project. I'm trying to build a small water pump that will be controlled by an optical liquid level switch. I have the motor, a Rule/Xylem Inline iL200 that requires a DC 12V 2.8A power supply (https://www.xylem.com/en-tj/brands/rule/rule-products/slimline-pumps/). I have a couple of questions:
1. I've found an AC 120V input, DC 12V 3.0A output power supply, but can't find any power supplies with 2.8A output. Will the 3.0A output be compatible with the pump's 2.8A motor?
2. I'm looking at using a sensor switch such as the SMD Fluid Controls OS5 (https://www.fluidswitch.com/wp-content/uploads/sites/2/2020/05/Basic-Optical-Switch-OS5.pdf). The idea is for the water pump to turn on when the optical liquid level switch detects water, and then turn off when water is no longer detected.
I'm not sure if another component such as a solid state switch or mosfet is required. Any help would be greatly appreciated, thanks.
Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3
 

sghioto

Joined Dec 31, 2017
2,394
IF the motor only draws 2.8 amps max then a 5 amp supply should be fine.
Like this one from Amazon. Item # B07NR6FPN9
1615845122640.png
 
Last edited:
Top