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Topic: LCD messes up whenever my relay turns on (Read 6863 times) previous topic - next topic

1st_joker

I am having the same problem; can you give a little bit more information what you mean by "putting diodes on every connection going back to the arduino"? Thanks.

CarlW

Here is a link to an article about diodes...

http://www.electronic-factory.co.uk/diode-limiting-and-ciruits/

What I have done is used alligator clip jumper cables to "try" the diode on the offending device and see if it helps before doing a lot of soldering.
The long term solution is to solder a diode from the positive to the negative terminals of the offending device. To be honest I forget which way the diode goes! My memory tells me the diode band goes to the positive terminal. It will only work one way though, that is for sure!

I've only done this on DC devices (solenoids and relays) and it suppressed the noise that was interfering with the arduino and thus the display.

The other thing that helped was having a common ground for all the devices and the arduino.

Good Luck.

floresta

Quote
It will only work one way though, that is for sure!

It will work the other way ... for a very short period of time.

Don

Paul__B


I am having the same problem; can you give a little bit more information what you mean by "putting diodes on every connection going back to the arduino"? Thanks.


That's a bit of a worry in itself, as it does not clarify what the problem was, or provide a "fix" that is meaningful in any other case; it is simply a completely random move that happened to solve the problem at that moment by accident.

The actual problem will have been one of two things, either the power supply was insufficient to reliably actuate the relay, or some impulse was being caused by switching the mains circuit, that was conveyed to the Arduino and caused an interruption of its program.  It is certainly the case that there should always be a diode across the relay to absorb the inductive voltage impulse when it is turned off, the direction being such that the diode does not conduct when the relay is being energised by the transistor.

Sparkie

To all that have weird characters on LCD screen when you run 117 Volts from a relay using the Arduino!
This is what I found.  Put a 470 uf electric capacitor across the SIGNAL pin on the relay and ground. That fixed all the issues for me.
I driving the relay with a separate power supply, which didn't work which led me to believe It could be the signal pin and sure enough it was. Hope this works for everyone else having the same issue.
1/11/2018

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