# Solenoid + Transformer + Current buildup interval

• Sefrez
In summary, the conversation was about the speaker creating solenoids with a core of metal and attempting to induce current through the outer winding by driving DC current through the inner coil. They then made calculations to determine the expected results and discussed the time it takes for the driven current to reach maximum and the induced voltage. The conversation ends with a suggestion for using a hacksaw blade to interrupt the current.
Sefrez
I decided to make a couple solenoids. Not too many loops on them though as I need higher gauge wire. After getting that I put one in the other and in that a core of metal that had some iron in it. I tried inducing a bit of current in the outer winding by driving DC current through the inner coil - I also tried having the reverse done. Now I know you need AC current, but I thought that I would at least get a pulse of an electric potential difference when first sending current through. While I did, it was extremely small.

I then made some calculations and it seemed to show what I was getting was to be expected. I need a much greater coil density - especially the coil to be induced (I am wanting to up the voltage.)

But my question lies with the time at which it takes for the driven current to reach maximum, and thus the B field. When calculating I got about 31.93 ms. I know I did not have a lot of precision with obtained measurements, but could this be a plausible time interval? I know that it wouldn't make sense to say that it is instantaneous for many reasons, though one being that that would mean the magnetic field is created instantaneously and thus infinite induced emf on the outer coil - that's not so.

Thanks.

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Hi Sefrez. I'd regard that as a feasible time. With only a few dozen turns the inductance will be low. Instead of looking for the induced pulse when you connect the battery, look for it when you disconnect the battery. dI/dt is likely to be much greater and hence the induced voltage greater. You can interrupt the current sharply by breaking apart a connection. To make many rapid connect/disconnect actions, run one of the wires along the teeth of a hacksaw blade incorporated into your current's path.

## What is a solenoid?

A solenoid is a cylindrical coil of wire that produces a magnetic field when an electric current is passed through it. It is commonly used in electromagnets, relays, and other electromagnetic devices.

## What is a transformer?

A transformer is a device that uses electromagnetic induction to transfer electrical energy from one circuit to another. It consists of two or more coils of wire wrapped around a magnetic core and is commonly used to step up or step down the voltage of an alternating current.

## How does a solenoid and transformer work together?

In a solenoid, the magnetic field created by the current in the coil can be used to induce a current in another nearby coil. This is the basic principle of electromagnetic induction, which is also used in transformers to transfer electrical energy from one circuit to another.

## What is the current buildup interval in a solenoid and transformer system?

The current buildup interval refers to the time it takes for the current to reach its maximum level in a solenoid and transformer system. This interval is influenced by factors such as the number of windings in the coils, the strength of the magnetic field, and the characteristics of the circuit.

## How can the current buildup interval be controlled in a solenoid and transformer system?

The current buildup interval can be controlled by adjusting the number of windings in the coils, changing the strength of the magnetic field, or altering the characteristics of the circuit. It can also be controlled by using different types of materials for the magnetic core or by changing the frequency of the current.

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