12 Volt Power

Other Hardware General Electronics
1

I'm working on a project that uses a 12v solenoid as well as relays and lights running at 5v. I purchased a 12v power supply to use for my project and I'm running into some issues. If I plug the power supply in while I'm plugged into USB everything works as expected and when I plug the USB cable the Arduino functions correctly as well. My issue is when I try to run solely on the power supply the Arduino stops executing the program and the relays will click on and off every few seconds. If I plug the USB in at this point this behavior stops and it works as it should. I have verified the power supply is putting out 12v consistently.

I am running an Uno R3 with an Ethernet shield. The power supply is this one. http://www.amazon.com/gp/product/B005JRGOCM/ref=oh_details_o08_s00_i00?ie=UTF8&psc=1 Am I having an amp issue?

2

Could be your power supply ground is not connected to Arduino ground except when the USB cable is plugged in. Check the connection.

3

What happens if you place a 100-470uf capacitor form Vin to ground using only the 12VDC supply?

4

Connection looks good. I could see it being that if the issue if it didn't work fine when both are plugged in and I remove the USB.

Same result with the capacitor in place.

5

Could be too much load with relays and solenoids. Try replacing the solenoids with current limited LEDs and see if it runs.

6

I thought about that too but I'm using a relay to trigger the solenoid since it's 12v. Total I have 5 relays hooked up.

7

Do you have a reverse biased diode between Vin and ground. maybe voltage spikes from the relays are causing problems when you are feeding power to arduino that way. If we could see a diagram of your circuit it might help :wink:

8

Check your GNDs are connected and measure the 5V pin of the Arduino when it is acting funny. It could be that on-board regulator is getting pushed too hard and shutting down.

9

I think its about time you showed us a circuit diagram, it sounds like you have no power to the arduino at all when you disconnect the USB.
Have you checked that the board is being supplied when you have the USB unplugged.
Tom.

10

Here's my stab at a diagram. First time doing it some I'm not convinced I completely did it correctly. I'm using a 4-channel SanSmart Relay to control 110v Quad box and another stand alone relay to control the 12v solenoid.

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11

Stab is right. Man I hate fritzing! Give me a decent schematic anyday.
At least resize the wiring layout so its 1000 wide and not 4 screens wide.

12

Like I said...first time.

I checked the 5v pin with the USB plugged in and it holds right at 4.7v. When I remove the USB the voltage moves to 4.92v and all the weirdness starts.

13

Four 5V relays taking maybe 70mA each when turned on, that's 280mA, plus about 50mA for the Arduino components is 330mA, times 7V voltage drop in the regulator is well over 2W power dissipation - which is more than the Arduino 5V regulator is designed for. It's probably going into thermal shutdown. If you are using a 12V supply then it makes far more sense to use a 12V relay board than a 5V one.

14

Thanks dc42! That makes sense. I'll change my relays over to 12v ones.

15

Where is the solenoid getting its supply, looks like its the arduino board.
This would cause an overload of the arduino regulator plus spikes from the solenoid coil.
Tom.

16

Schematic are preferred. They are much more clear.

Even if you just draw it on a piece of paper, take a picture with your phone, and upload it.

17

I wanted to give a quick update. I switched out the 4 port relay board for a 12v version and everything is working and stable now. Thank you for all of the help!