Capacitor discharge through a coil, need to find current

In summary, the conversation is about designing a circuit to discharge a capacitor through a coil of wire in order to create a large magnetic field. The circuit is an undriven RLC circuit with a charged capacitor, an inductor, and a resistor. The goal is to find an equation for the current through the coil as a function of time, taking into account the small inductance of the capacitor. A helpful resource for this is a thread on a forum and a program called LTSPICE IV.
  • #1
nrlightfoot
2
0
I'm designing a circuit to discharge a capacitor though a coil of wire to make a large magnetic field, which is basically an undriven RLC circuit which starts out with a charged capacitor in series with an inductor and a resistor (the coil having a certain resistance in addition to its inductance).

I'm trying to find an equation for the current through the coil (inductor) as a function of time after starting to discharge the capacitor. I need to find this so I can select proper components to give a sufficient magnetic field without burning out the coil.

I also know that the capacitor will have a small amount of inductance which needs to be factored in. Please let me know if there is anything else like that I would need include in the calculation.
 
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  • #3
Thanks Bob,

That thread was helpful, I think if I had that program you were using I could figure out what I need to know. What's the name of that program, and do you have that RLC circuit file you made that you could send me if I can get the program?

-Nick
 
  • #4
Hi nrlightfoot-
I was using free LTSPICE IV available on the web. Please look at my posts #26 thru 32 in the referenced thread:
https://www.physicsforums.com/showthread.php?t=327153
Here is a 16,000 amp, 2 ms wide half-wave current pulse using series diode in thumnail.
Bob S
 

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Related to Capacitor discharge through a coil, need to find current

1. How does a capacitor discharge through a coil?

When a capacitor is connected in series with a coil, it stores energy in the form of an electric field. When the circuit is closed, the capacitor discharges its stored energy through the coil, creating a changing magnetic field.

2. What factors affect the current in a capacitor discharge through a coil?

The current in a capacitor discharge through a coil is affected by the capacitance of the capacitor, the inductance of the coil, and the resistance of the circuit. It is also influenced by the voltage of the capacitor and the time constant of the circuit.

3. How do I calculate the current in a capacitor discharge through a coil?

The current in a capacitor discharge through a coil can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). You will also need to take into account the capacitance (C) and inductance (L) of the circuit to accurately calculate the current.

4. Can the current in a capacitor discharge through a coil be controlled?

Yes, the current in a capacitor discharge through a coil can be controlled by adjusting the values of the components in the circuit. For example, increasing the capacitance or inductance will result in a slower discharge and therefore a lower current, while decreasing these values will result in a faster discharge and a higher current.

5. What are some practical applications of capacitor discharge through a coil?

Capacitor discharge through a coil is commonly used in electronic circuits to create a high-voltage spark, such as in ignition systems for cars and gas-powered appliances. It is also used in the production of electromagnetic pulses for electronic warfare and medical devices, and in the creation of electromagnetic fields for induction heating and wireless charging.

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