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# How much power to control 3 x12V Solenoids? Answered

Hello! :)

Newbie here (and to using Arduino). Sorry in advance for the dumb question:

If I'm using an Arduino uno to control three 12V push-pull solenoids, how much external power do I need? I tried using  3-12V power supply to control 1 solenoid only, but it didn't work.

FYI, in the circuit I'm also using:
- TIP120 transistor
- 1N4004 Diode
- 1K resistor
(don't have a motor shield to replace all of the above..)

Not sure where I'm going wrong. Could anyone help me please? Thanks!

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## 10 Replies

Yonatan24 (author)2015-09-04

I do not know anything about arduinos but what I do know is that if you put them is parallel you need 12V and if you put them in series you need more than one each time you need to add that voltage again...

1=12

2=24

3=36

And so on... But this is correct only when that arebin series

mpilchfamily (author)2015-04-26

You need 12V going to each. Now how much current you'll need will depend on the specs of the solenoids. Showing use the circuit your using will go a long way to getting you the assistance you need.

Joanne55 (author)2015-04-26

Thanks. I actually realised after posting that what I want to do would require the solenoids not to work simultaneously (and i did a 2d long array to plot timings for each). So I used 2 x 9V batteries and it works perfectly!

steveastrouk (author)2015-04-27

Your next question is going to be "why do my 9V batteries not run for very long"

Joanne55 (author)2015-04-27

Haha no I'm aware they don't, but that's just what I had and I needed to test stuff [flow of sand, see image] asap. I'll get a multivoltage power supply tomorrow as a substitute..

However my plan isn't working yet and it seems I need larger solenoids (mine are 12V 1A 10mm stroke 600g). I tested one with a button, and the solenoid pulled when I pressed it, allowing the sand to pass through, but when i unpressed the button it wasn't able to push the sand and cover the opening on my wooden piece..too much pressure, weak spring.

steveastrouk (author)2015-04-27

Use two solenoids, one to open, one to close.

Joanne55 (author)2015-05-06

Just saw your reply, oops! Yep, thought about that, good idea. But i ended up finding cheap solenoids with a 5.5 kg force, and adding a spring at the back for the 'push', worked perfectly. Installation completed:

Joanne55 (author)2015-04-26

circuit:

rickharris (author)2015-04-26

OR you could operate one of the solenoids from a 12 volt source, say a car battery and measure the current flow required to hold it in.

Ideally you should measure the peak current that will flow in the first few milli seconds of connection. but if you only have a multi meter this may be hard to do.

REMEMBER when it is turned off the solenoid will generate a considerable amount of reverse voltage as the magnetic field collapses often several 100 volts! You will need to snub this with a diode..

Joanne55 (author)2015-04-26

Thank you for your reply, sorted out! (Check reply to mpilchfamily)