Go Down

Topic: Using VIN and GND pins to drive solenoids? (Read 143 times) previous topic - next topic

pburto

I have a 12V power supply, plugged into my Uno. The Uno operates a relay shield, which is used to drive 12V solenoid valves.  The same 12V power supply will operate the solenoid valves.  The power supply will provide sufficient current for everything.

I'd rather not tap into the wires of that power supply. Instead I'm hoping to use the VIN and GND pins, to drive the solenoid valves.  Are these two pins essentially the same thing as the external power jack?

My worry is that both pins may not be "directly" from the power supply since they go through the board.  I'm fairly confident the VIN pin (voltage in) is exactly that: Input voltage, before passing through any power regulation.  If so, (and please confirm) then I would think it's somewhat isolated from the Arduino by the internal 5V power regulation. 

But the GND pin may be different.  It okay if the GND pin, which I know is the Uno uses as its own ground, is also used for the ground wire powering my solenoids?

As a follow-up, would it be possible to power the Arduino directly through those pins, without using the external power jack?

terryking228

Hi,

Electrically that is true. For DC.

You may have problems with EMI (ElectroMagnetic Interference) from switching the solenoids, though.

You may need to use optically-isolated relay boards also.. Those relays on the shield are awfully close to the Arduino circuits.

See Arduino Power here: http://arduino-info.wikispaces.com/ArduinoPower
Then see the link here:
http://arduino-info.wikispaces.com/RelayIsolation

You should have a common ground point where everything comes together; probably the - connection of your 12V supply, also connected to local earth ground.
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

pburto

Thank you.  Actually the "shield" that I have is called a "shield module" by Sunfounder.  It doesn't plug in to the top of the Uno, instead it's a couple inches away with wires.

Unfortunately my question becomes moot, because I discovered two problems with products I bought:

1) My alleged 12V power supply -- ISN'T.  I measured 17.3 volts.  (So who knows if it's actually capable of the current it claims.)  That's under the absolute max for the Uno, but it's not recommended and this will be plugged in constantly with poor ventillation.

2) My alleged 12V solenoid valves -- AREN'T.  They will operate at 17.3 volts, but they won't work at 12V.  I suspect they are 24V valves.

Soo... Although I COULD make it work for a while with a single power supply at 17.3V, I won't.  I'll get a new 24V power supply and add an extra layer of power regulation, supplying the Arduino with 12V and the solenoids with 24.

MarkT

Solenoid valves only work with the right pressure applied.  The pressure does most of the work.  Have you a
allowed for this in testing them?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

pburto

Yep, I tested them while they were installed in the plumbing.

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy