Simple question please!

Discussion in 'General Electronics Chat' started by TE5LA, Aug 21, 2014.

  1. TE5LA

    Thread Starter New Member

    Aug 21, 2014
    sorry but I am a noob to electronics but here goes.

    I have a 12v DC adapter outputting 2amp which and I need to hook it up to a solenoid which is super strong. I tried with a 12v DC 2a solenoid (20N force) and its really really weak. I then tried with a 12v DC 300mA solenoid (6N force) and its super strong however it soon got hot and went bust (over current I assume). Can someone unlock this mystery for me and tell me what the best solenoid I should get for the adapter (I am stuck with the 12v 2a adapter).

    12v 2a adapter

    12v 2a solenoid (WEAK when working with above adapter, possibly defect?)

    12v 300mA solenoid (burned out)
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    It says that the one that burned out is 800mA; not 300mA.

    It is possible that this solenoid is not rated for continuous duty. 12V * 0.8A = 9.6W. That would get quite hot...
  3. antonv


    Nov 27, 2012
    Hi, first of all, the correct way to talk about a power supply's output current is something like "it can put out up to 2A". It won't force 2A out. Things have to obey Ohm's Law. It will put out as much current as your load wants; if your solenoid is a 800mA solenoid the power supply will only put out 800mA.

    If it's a 2A power supply an the load has a low enough resistance that it is going to want more than 2A then your power supply will fail one way or the other to keep producing 12V.

    If your supply puts out 12V then the little solenoid should not have gone bust unless something was already wrong with the solenoid.

    The power supply vendor claims it's regulated but I wonder if it is. Unregulated supplies only put out their rated voltage at full current (2A in your case), any load smaller than that will have to put up with a higher voltage and therefore higher current and so higher power than it was designed for.

    Can you measure the voltage across the solenoid once it's connected to the supply?
    anhnha likes this.
  4. MrChips


    Oct 2, 2009
    Metalmann and #12 like this.