Hello all.
I have two linear actuators that, when in motion, are causing my LCD screen to freak out. They are 12VDC actuators being controlled through a relay module, powered separately from my Arduino.
Power for the actuator is completely isolated from my Arduino/LCD. The issues never show up when the relays are switching. It is just while the actuator arms are extending or retracting. It takes roughly 30 seconds for the arm to fully extend, and a few seconds in, a spare character or two will start popping up here and there, with occasional full-blown freakouts.
I just placed a 0.1μF and 1000μF capacitor across pins 1 and 2 of the LCD screen (also tried 10μF first before switching up to the 1000). This is not resolving the issue. I considered adding capacitors to the data pins, but wasn't sure if that would delay actual signals to the LCD, in addition to warding off spurious signals.
Any tips? Or is there some sort of function that allows me to "freeze" my screen while the actuators are in motion (not ideal, since I have a loading bar that indicates the progress of the actuator).
Edit: Wrong forum. Whoops. Any way to delete posts?
There is no sure fire solution but you are best next to try and reduce the interference generated by the linear actuator by decoupling the power supply to it using the pi circuit which is the last on this site :- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html
Also try a ceramic on the actuator as close to the coil as you can. You could also try using a separate power supply.
I just placed a 0.1μF and 1000μF
Was the smaller one a ceramic? It is the only type that will work.
Just got done reading through that a little while ago :). Yep, putting small capacitors near the actuator now. Easiest first solution. When you say "near", do you mean as close as possible? I have about 4 inches of wire from my capacitor to my actuator coil.
I also ordered some copper tape to wrap around my lcd wires. Someone else mentioned that had worked for them.
Smaller capacitor is ceramic, yes.
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Do you have any wires that go to the controller running beside wires that have the motor current flowing?
Thanks.. Tom.. 
That Pi circuit has an inductor in it. The bigger the inductor the better is the protection but make sure it can handle the current. A distance of 4" is a bit too far, can you get inside and attach it on the motor's coils?
Hey Mike, given that the power to my relays and actuators is totally separate, including separate grounding, will this work towards solving my apparent issue of EMI?
And to follow up, should I be more concerned about the proximity of my actuator leads to my LCD screen/LCD cable, or is the interference more likely to come from the actuator itself?
will this work towards solving my apparent issue of EMI?
Yes.
should I be more concerned about the proximity of my actuator leads to my LCD screen/LCD cable, or is the interference more likely to come from the actuator itself?
Both. It starts in the actuator but can be propagated down the lines and then re-radiated.
Hey Mike. I made that circuit you have on your site. Between that, adding copper tape to my LCD signal wires and to my actuator power wires, wearing a foil hat, and building an altar to the old gods for mercy, I was able to almost completely eliminate any interference. Thanks for your help.
Hi,
Can you post a picture of your project please?
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom..
Strictly speaking, your Arduino should be in an earthed metal box (with no holes which makes it difficult to get the wires out). All wires to the actuators should be twisted pairs (preferably shielded) and both circuits should be earthed to real earth at a star point (on the box) with the heaviest wire that you can use.
I think that shielding the wires with copper tape and earthing the tape was a good idea. Your inputs to the Arduino need to be screened, short and have low pass filters on them (a subject in itself).
I hope that this helps
Dead_Ard
TomGeorge:
Can you post a picture of your project please?
Gladly!
The top and bottom "deadbolts" (notice the door is open) are the two actuators. The other is attached to a gear racl. The arduino itself is a few inches below the panel in the wall, fairly close to the bottom actuator. This whole thing is for an escape room we are building.
TomGeorge:
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Well... It's a bit embarrassing to be honest. One, I've been told that my method for reversing the direction of the actuators, while consistent for my needs, is wrong. Secondly, it is such a complicated and involved circuit that, unless I have more problems in the future, is not worth the time to draw it up. Also, we are hoping to launch this weekend, so now that it works, other problems beckon.
Secondly, it is such a complicated and involved circuit that, unless I have more problems in the future, is not worth the time to draw it up.
Please note that if you don't draw it up now you will never be able to in the future, you will forget.
Hi,
It is just while the actuator arms are extending or retracting. It takes roughly 30 seconds for the arm to fully extend, and a few seconds in, a spare character or two will start popping up here and there, with occasional full-blown freakouts.
AND
One, I've been told that my method for reversing the direction of the actuators, while consistent for my needs, is wrong. Secondly, it is such a complicated and involved circuit that, unless I have more problems in the future, is not worth the time to draw it up.
It seems you NEED to draw a circuit diagram, as the two could be related.
If you don't draw a circuit diagram NOW, in the future, you or anybody who has to trouble shoot your project will be at a great disadvantage.
Can we have a picture of the wiring side of your project please?
Wiring layout can have a big effect on how a circuit performs.
Thanks.. Tom...
