Question about the FM Transmitter Project

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joh
Newbie Pyro
Posts: 2
Joined: Sat Jul 12, 2014 8:23 pm

Question about the FM Transmitter Project

Postby joh » Sat Jul 12, 2014 8:34 pm

Hello,

I really like your FM transmitter Project and I´d like to build it by my selfe.
I only have one problem:
What do you mean with Toroid Core (AL=25)?
Is that the inner or the outside diameter?
Or is that a value for the inductance or something else?
is ist possible, that you send me a link with a core that would fit for the project?

Thank you verry much,
Joh

ThePyroElectro
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Re: Question about the FM Transmitter Project

Postby ThePyroElectro » Sun Jul 13, 2014 6:41 pm

joh wrote:Hello,

I really like your FM transmitter Project and I´d like to build it by my selfe.
I only have one problem:
What do you mean with Toroid Core (AL=25)?
Is that the inner or the outside diameter?
Or is that a value for the inductance or something else?
is ist possible, that you send me a link with a core that would fit for the project?

Thank you verry much,
Joh


Hi Joh,

I found a random toroid core that was small at a nearby electronics shop and that's how they rated them. AL=25 means:
AL = Value which relates Inductance per 100 or 1000 turns of wire


Since FM frequencies are 98-108 MHz'ish the RF inductor can't have too high of a value, so a low value toroid core was used.

These guys sell an array of toroids with iron powder - http://www.jpmsupply.com/servlet/the-Toroids/Categories

You might have to do some hunting to find the exact same toroid that I used. But in reality, all you need is a similar AL value toroid and a signal analyzer. That way you can measure the output frequency with the analyzer and then tweak the number of turns on your toroid until you get to the frequency you want.

joh
Newbie Pyro
Posts: 2
Joined: Sat Jul 12, 2014 8:23 pm

Re: Question about the FM Transmitter Project

Postby joh » Tue Jul 15, 2014 7:44 pm

ahh ok, I´ll buy some cores and ask some guys if i can have their analyzers :)

thank you verry much for your answer.

see you ;)

jamesjogi08
Newbie Pyro
Posts: 1
Joined: Thu Apr 16, 2015 8:00 pm

Re: Question about the FM Transmitter Project

Postby jamesjogi08 » Thu Apr 16, 2015 8:15 pm

is ist possible, that you send me a link with a core that would fit for the project?






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