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Topic: Problem with LCD and Motor (Read 10 times) previous topic - next topic

dc42

#40
Oct 11, 2012, 11:06 am Last Edit: Oct 11, 2012, 11:10 am by dc42 Reason: 1
Assuming the solenoid is powered from DC, connect a diode (1N400x or similar, x = 1 to 7) in parallel with the solenoid, wired so that when the solenoid is engaged it does not conduct (otherwise it would short out the power supply).

Also, don't run the solenoid wires close to the LCD or its wiring, and do run the solenoid wires close to each other so that the area enclosed by the 12V supply - relay contacts - solenoid circuit is kept to a minimum.

Also, make sure that the +5v and ground wires from the LCD go directly to the Arduino, not to some common connection that then has a shared wire connecting it to the Arduino.
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daytrader152

Thanks a lot, mate! Placing the diode across the solenoid did the trick! It's much more stable now. I think I just need to place the diode even closer to the solenoid to completely get rid off the problem. Right now the diode is about 30cm away from the solenoid.

I have another similar circuit with a LCD and 256 relays (to control 256 electronic solenoids). This setup also experiences the same rubbish character problem on the LCD, so I will need to place the diode across all the solenoids as shown in the attachment. Is there an easier way to place the diodes? It's quite a bit of work to cut the wires and solder the diodes on all 256 solenoids. Thanks again!

dc42

From the photo, it looks as if those solenoids are held together by 4 screws with hex or Torx heads. It might be worth disassembling one, to see whether there is room to fit a diode inside (although that will probably invalidate the warranty). If space is limited, then depending on the current taken by the solenoid, you may be able to use a smaller diode. You can also get 1N400x diodes in SMD packages.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

amitkrj

I am also having similar issue. My LCD connected to the UNO displays strange characters after turning on/off the 5V relay for a 10-15 times. The relay controls a 220v AC solenoid and another relay controls a Contactor (220V AC). Both relay has diode contected (IN4007).
I tryed putting cap 100uF around display but LCD still displays strange characters.
Does anyone have any suggestion for me. Thanks

liudr

You tried a 1n4004 diode yet?

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