oddabe83 Posted February 10, 2007 Report Share Posted February 10, 2007 Hi!I bought this solenoid from an electronics hobby shop. It consists of just coils of wire, with a metal rod in between, such that when current is passed thru the solenoid, magnetic field is created and the rod "sucks" inwards. The problem is, the solenoid is connected by a DC supply. As soon as it is connected, even though the rod did suck inwards, the whole circuit shorts itself. The solenoid's resistance is only 3.6ohms. As such, if I put a resistor in series with it, little voltage is passed thru it (it needs at least 6V), and it wun work. Can anyone kindly draw me a circuit that alleviate such situation? I need 6V to pass across the solenoid, and as little current as possible..Thanks in advance! Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 11, 2007 Report Share Posted February 11, 2007 Just calculate the required current by using Ohm's Law. I= 6V/3.6 ohms= 1.67A. Quote Link to comment Share on other sites More sharing options...
oddabe83 Posted February 11, 2007 Author Report Share Posted February 11, 2007 Do u mean if i provide the correct amperage, the circuit will not short itself? Is it true that solenoids in a DC circuit is actually a short circuit? Quote Link to comment Share on other sites More sharing options...
ante Posted February 11, 2007 Report Share Posted February 11, 2007 The solenoid must have no less than the calculated amperage to work as intended and it will grab this current when the correct voltage is available. No, that Quote Link to comment Share on other sites More sharing options...
oddabe83 Posted February 11, 2007 Author Report Share Posted February 11, 2007 Hi,I suspect it might short circuit as the coil is really just wires coiled up into a lump. Are inductors actually solenoids? Inductors actually shorts themselves if connected to a DC supply right?What would you suggest to prevent the high voltage? Will a diode help? Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 11, 2007 Report Share Posted February 11, 2007 Why do you say the solenoid shorts?Does it cause a 6V battery or a 6V power supply to get hot?Does it cause the battery or power supply's voltage to drop?Is the battery or power supply capable of feeding a 1.67A load? Quote Link to comment Share on other sites More sharing options...
ante Posted February 12, 2007 Report Share Posted February 12, 2007 You know 3.6 Ohms is not a short! A solenoid is an inductor.What sort of power source do you use? Quote Link to comment Share on other sites More sharing options...
Fowkc Posted February 13, 2007 Report Share Posted February 13, 2007 A solenoid is not really a "short circuit" in the normal sense of the word.If you drew out the wires in a solenoid or inductor, the behaviour would be of a normal piece of wire. The coiling up of the wires means that the coil creates a magnetic field inside it. This magnetic field in turn sets up a voltage across the solenoid which will oppose the applied voltage.The measurement of the resistance of a solenoid (as far as I know), is not a very good indicator of the current it will draw, as the behavior is dependant on that current.Think about a transformer winding: low resistance, but the behaviour when a voltage is applied is very different from a resistor of the same value. Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 13, 2007 Report Share Posted February 13, 2007 The magnetic field in a solenoid sets up a voltage across it that opposes the applied voltage, during the slow build up of the current. The solenoid is an inductor that builds up current slowly. When the current reaches the max then it is exactly the same as in a resistor with the same resistance as the solenoid. Quote Link to comment Share on other sites More sharing options...
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