Help needed with my project (electromagnetism)

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GiannisM
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Joined: Fri Feb 12, 2021 10:05 am
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Help needed with my project (electromagnetism)

Post by GiannisM »

I am a teacher and I am trying to create an electric door bell .
This is a project that I am going to share it with my class next week, but I unfortunately I amnot able to make it work so far.
I have make an electromagnet that normally should attract the metal and in this way the circuit will be disconnected. The electromagnet works, but when it is connected with a battery but when it is connected to the circuit nothing happens.
So, I decided to change battery in the circuit. Firtsly, I used a 4,5 Volt battery and now I am using a 9 volt battery.
Now, the electromagnet doesn't work, but I noticed that sparks has been produced in a specific part of the circuit. What does this mean?
Could you please help me to find what I am doing wrong?
Thank you very much!
rmarz
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Re: Help needed with my project (electromagnetism)

Post by rmarz »

GiannisM - A doorbell should be fairly simple. I don't have a diagram of what your circuit looks like, but here are the basics. The current to the electromagnet will pass thru the mechanical arm that has a normally 'closed' contact built in. As the electromagnet moves toward an iron object, the contacts will open and current will be interrupted and the electromagnet will return to it's starting position (assuming it has a spring action that will accomplish that). That will cause the contacts to close again and re-energize the electromagnet and this cycle will continue at a rapid rate until current is turned off. Basically it is operating like a buzzer. Obviously the moving electromagnet will strike a bell of sorts.

Some things to check. Is there a short circuit between the power source and the object the electromagnet is striking? After the electromagnet moves, do the contacts open properly to stop current flow? You mentioned seeing sparks in other parts of the circuit. If there is a possible short circuit, try insulating the part of the electromagnet that is striking the iron object with a piece of tape to see if that corrects the problem. A photo oh your setup would help.

You suggested that the electromagnet works, but when you put it into the circuit it stops. I don't quite understand that. Good luck, if you can provide us with any other information, perhaps we can be more helpful.

Rick Marz
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