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Linear Actuator noise reduction

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3224TM

New Member
Hello. Extreme newbie here asking for some help.

I'm controlling a 12v linear actuator using a 2 channel relay. From what I've been reading, I should be using a bypass capacitor somewhere in the circuit to help with noise reduction? The problem is, I don't know where to place the capacitor. My actuator has 5 wires: Positive, Negative, Potentiometer signal, Potentiometer Reference 1 & Potentiometer Reference 2. Any information would be great, and thanks in advance.
 

MikeMl

Well-Known Member
Most Helpful Member
There could be issues with the relays causing an inductive spike when they are turned off, not just motor commutation noise. The position changes relatively slowly, so the Pot signal can be aggressively low-pass filtered.

How is the 3.3V/5V derived?

Where is the common ground between the 12V supply and the logic supply?

We need to see the entire circuit to comment.

ps. I am using an Arduino to contol my drive-through swing gate using a 12V linear actuator. I have been down this road...
 

3224TM

New Member
There could be issues with the relays causing an inductive spike when they are turned off, not just motor commutation noise. The position changes relatively slowly, so the Pot signal can be aggressively low-pass filtered.

How is the 3.3V/5V derived?

Where is the common ground between the 12V supply and the logic supply?

We need to see the entire circuit to comment.

ps. I am using an Arduino to contol my drive-through swing gate using a 12V linear actuator. I have been down this road...
Thank you for your reply. I don't know how to draw a proper schematic, but I do have a picture of the circuit. I did my best to properly place the connections over the pictures in their proper spot. Thanks once again for your assistance. I'm learning. Circuit.JPG
 

MikeMl

Well-Known Member
Most Helpful Member
The relays are de-glitched on the relay board. I like that your -12V lines are all returned to the - lead of the power supply (single point ground, motor current not flowing anywhere in the Arduino PCB); that makes ground-loops less likely.

Try it.

If you get noise in the AD input from the positition pot, put a 10uF capacitor, + to the AD input, - to Uno local GND. A 0.01uF disk ceramic capacitor between the red-black motor leads (close to the motor as possible) might help...
 

Pommie

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Is the noise you're trying to reduce audible noise or electrical noise?

Mike.
 

MikeMl

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... What does AD mean?
Analog to Digital converter. I assumed you were reading the pot wiper (analog) voltage into the Arduino to see how far the actuator pushrod is extended?
 

3224TM

New Member
Analog to Digital converter. I assumed you were reading the pot wiper (analog) voltage into the Arduino to see how far the actuator pushrod is extended?
Thank you. Yes, that's what I'm doing. Reading the wiper data into the Arduino analog pin A0.
 

MikeMl

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Most Helpful Member
Thank you. Yes, that's what I'm doing. Reading the wiper data into the Arduino analog pin A0.
So is the noise you are trying to reduce evident in the AD readings? If not, how does the noise manifest?
 

3224TM

New Member
So is the noise you are trying to reduce evident in the AD readings? If not, how does the noise manifest?
The readings from the actuator (wiper) are fluctuating a bunch. The range of the actuator is (fully retracted = 112, fully extended = 912). If I tell the actuator to move to let's say halfway (512), it goes to that location (within my dead band forgiveness) and stops but, the readings coming into the arduino fluctuate about 50 points (values?). Id like to tighten that up a bit. Part two is, while the thing is running, it will lock up the arduino and everything will stop after a few seconds. It's completely intermittent. Sometimes I can get about a minute before it stops, other times, only a few seconds. If I remove the actuator from the circuit, the thing will run flawlessly.
 

3224TM

New Member
The relays are de-glitched on the relay board. I like that your -12V lines are all returned to the - lead of the power supply (single point ground, motor current not flowing anywhere in the Arduino PCB); that makes ground-loops less likely.

Try it.

If you get noise in the AD input from the positition pot, put a 10uF capacitor, + to the AD input, - to Uno local GND. A 0.01uF disk ceramic capacitor between the red-black motor leads (close to the motor as possible) might help...
Once again I need to say "thank you" for all your help! Additionally, since i'm very new to this sort of thing, I made 2 illustrations of where I think I understand where you are telling me where to place the capacitors. If you could take a look and let me know if I'm understanding correctly? Thanks once again. Circuit-2.JPG Circuit-3.JPG
 

MikeMl

Well-Known Member
Most Helpful Member
10uF across the AD input; not the motor. The largest capacitor I would put across the motor is ~10nF (0.01uF).

Put a DC voltmeter across your 12V supply and measure the voltage while the motor is running. Does the voltage drop as the first motor starts up? While it is running?
 

3224TM

New Member
10uF across the AD input; not the motor. The largest capacitor I would put across the motor is ~10nF (0.01uF).

Put a DC voltmeter across your 12V supply and measure the voltage while the motor is running. Does the voltage drop as the first motor starts up? While it is running?

Ok thank you, looks like I got it backwards. :-(
 
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