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ajbufort
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Hello All,
I am trying to run an electromagnet from my new power supply (TekPower HY3010E - 0-30V @ 0-10A). My electromagnet is a very simple air-core solenoid - 3-layers wound with 8 turns per layer from a 20-ft-long #12-gauge wire. The coil form is not big at all - a simple cardboard section of a toilet paper roll, and as my turns are few, a fair length of the wire trails the end of the winding uncoiled. I was running this off a 6V alkaline lantern battery, and now I want to adapt it to being powered by the power supply in a variable fashion.
Obviously, this is not the ideal electromagnet, but I am engaged in doing this as a learning exercise. I am after the flexibility/durability of power supplies as opposed to batteries, and I want to make sure I understand things correctly from the safety and workability perspectives, thinking on the right scale for such equipment. I anticipated that hooking up the coil as wound to the supply would trigger its short-protection mechanisms, and it has - the setup simply does not work. I know I need RESISTANCE, as my total resistance as calculated is .0318 ohms given the gauge of wire and its length. So here's my question:
What kind of resistance is best to add to my circuit such that I have maximum variability of operation (in terms of strength) of the electromagnet, either by varying the supply or by adjusting the resistor itself? How many ohms, rated at how many watts?
My initial attempts to work this out on my own are as follows:
(current state of affairs)
R is fixed at .0318 ohms.
I = V / R, so if I tried to apply even .32V to my circuit, I would go over 10A, already exceeding the limit of the supply.
Looking at it the other way around, if I applied 10A to my circuit, all I would get is a measley .32V. The supply likely has very high sensitivity to dead shorts, thus I can't even fine-adjust into this from 0. Fair assumption or not?
(where I want to be)
R = V / I, so if I want to be able to adjust my electromagnet to the max of my power supply's capabilities, I need an R = 30V / 10A= 3 ohms resistance in the circuit? And since P = I * V, I need it rated at 300W? (3 Ohm, 300 Watt resistor from Milwaukee Resistor, Part # 061813603.00E)? This all assumes a fixed-resistance solution, of course. I have not done any figuring regarding the fixed-supply-setting, variable resistor approach.
So am I on the right track here, or am I missing something?
Thanks,
-Anthony
I am trying to run an electromagnet from my new power supply (TekPower HY3010E - 0-30V @ 0-10A). My electromagnet is a very simple air-core solenoid - 3-layers wound with 8 turns per layer from a 20-ft-long #12-gauge wire. The coil form is not big at all - a simple cardboard section of a toilet paper roll, and as my turns are few, a fair length of the wire trails the end of the winding uncoiled. I was running this off a 6V alkaline lantern battery, and now I want to adapt it to being powered by the power supply in a variable fashion.
Obviously, this is not the ideal electromagnet, but I am engaged in doing this as a learning exercise. I am after the flexibility/durability of power supplies as opposed to batteries, and I want to make sure I understand things correctly from the safety and workability perspectives, thinking on the right scale for such equipment. I anticipated that hooking up the coil as wound to the supply would trigger its short-protection mechanisms, and it has - the setup simply does not work. I know I need RESISTANCE, as my total resistance as calculated is .0318 ohms given the gauge of wire and its length. So here's my question:
What kind of resistance is best to add to my circuit such that I have maximum variability of operation (in terms of strength) of the electromagnet, either by varying the supply or by adjusting the resistor itself? How many ohms, rated at how many watts?
My initial attempts to work this out on my own are as follows:
(current state of affairs)
R is fixed at .0318 ohms.
I = V / R, so if I tried to apply even .32V to my circuit, I would go over 10A, already exceeding the limit of the supply.
Looking at it the other way around, if I applied 10A to my circuit, all I would get is a measley .32V. The supply likely has very high sensitivity to dead shorts, thus I can't even fine-adjust into this from 0. Fair assumption or not?
(where I want to be)
R = V / I, so if I want to be able to adjust my electromagnet to the max of my power supply's capabilities, I need an R = 30V / 10A= 3 ohms resistance in the circuit? And since P = I * V, I need it rated at 300W? (3 Ohm, 300 Watt resistor from Milwaukee Resistor, Part # 061813603.00E)? This all assumes a fixed-resistance solution, of course. I have not done any figuring regarding the fixed-supply-setting, variable resistor approach.
So am I on the right track here, or am I missing something?
Thanks,
-Anthony