freewheeling diode with relais

Hi,

So I am making a simple project wich involves using a relais and arduino and transistor to turn on a lamp/motor.
I have been told to use a "freewheeling diode" (I don't know how to pronounce it in english so correct me if im wrong!). But ive seen some people on youtube and other sites not use a transistor and freewheeling diode. And it still works so what is the purpose of the transistor and the freewheeling diode? My teachers told me to use one. I"ll add a sketch down below so it may become clear. (Image does not belong to me).

Thanks in advance.

vrijloopdiode.jpg

vrijloopdiode.jpg

“ And it still works so what is the purpose . . . “

But for how long ?

How much electrical noise interference is caused ?

Just Use One !


Watch this:

You could always search 'purpose of free wheeling diode' and see what turns up.

Flyback diode and why you need one

Thanks u guys!

Any inductive load has the potential (pun!) to damage your circuit through the voltage spike
that results if trying to turn off the current suddenly. The free-wheel diode allows the current
to divert, continue and die-down without generating more than the forward-bias voltage of
a diode.

The analogy is with a push-bike, when riding it and you suddenly stop pedalling - without the
free-wheel that could break your legs or something like that.

Think of inductors as giving current "momentum".

Hoi rico469, alsnog welkom.

rico459:
My teachers told me to use one.

If your teachers told you to use it, didn't you ask them why ?

I could be wrong (because i'm incompatible with the school system / teachers i had at that time so i'm autodidact), but aren't those teachers there to explain these things ?
Should i be that teacher telling this, i would expect you to ask why.
That way i'd know your interest was arisen, and my explanation would land at the right spot.

If you would not ask such question, i'd have to assume you already know about this stuff.

OTOH, maybe us hobbyists can do better in explaining than your teachers would.

MAS3:
If your teachers told you to use it, didn't you ask them why ?

They told me thath I should already know (for some reason)

rico459:
They told me thath I should already know (for some reason)

Then they are not very good teachers.
A real teacher would help you understand and not just fluff you off with a comment like that.

You may repeat what I said as it is true.