inductor

[histrionic2002]

i am making a very simple FM transmitter but it requires a "5 turn coil". How can i go about this? am i simply, gonna wind magnetic wires and connect it to the circuit?

 

[Nigel Goodwin]

i am making a very simple FM transmitter but it requires a "5 turn coil". How can i go about this? am i simply, gonna wind magnetic wires and connect it to the circuit?

Simply get some stiff wire (I usually use the earth conductor from UK mains house wiring cable) and wrap it around a pencil - space the turns slightly apart, then you can adjust the frequency by opening or closing the coil.

 

[stevez]

I'll add a few things:
1. Usually the author will describe the coil in terms of diameter, number of turns and length. All of these things are important but it's not always necessary to be so precise. The description will get you close and increasing or decreasing space between the turns provides some adjustment. On a larger coil one might add or delete some turns.

2. Wire size isn't that critical in many applications - large enough to hold the shape, small enough to allow the proper number of turns and not be too expensive.

3. If the author provides a value in microhenries or millihenries you can come up with your own value. Formulas and charts for many situations are manageable by a hobbyist.

4. In an RF circuit the inductor is often paired with a capacitor so that the circuit is resonant at a particular frequency. If you know the frequency and value of the capacitor you can back your way into the value for the inductor.

Have fun.