I would post this in DIY, but considering it has something to do with FM, i thought i'd post it here.



so i want to build an FM transmitter, which you can plug a 3.5mm into it, and it will transmit it. so you can pick up the signal with FM radios.

does anyone have any schematics?

its for my elective, electronics (basics).

right now we can solder, and that's about it.

last time, we made a "siren" though it wasnt really loud.. 8ohm small speaker connected to a 9v battery.. (TINY)

i'm looking for a non-expensive (<$~10) one.

thanks

why don't you buy one at a hobby shop or radio shack.. they come with instructions, but i dont' know about scematics because they are soo simple.

there around 10 bux.

or there has to be thousands of schematics out there and even some in our text file section.

let us know.

http://www.aaroncake.net/circuits/fmtrans.htm

i hope i didn't sound brash.. but it would just be quicker to get a kit than to try and bang your head against the wall, especially if you have no reference point or experience.

you can mod the kit while learning more quickly.

i doubt your school wants you to re-invent the wheel at this point.

this here is obviously more than you need for this project, unless you want to try being very specific.

h ttp://www-personal.engin.umich.edu/~jglettle/class/eecs330/330report.pdf (http: //www-pers onal.engin .umich.edu /~jglettle /class/eec s330/330re port.pdf)

or you can just calculate the frequency you want to broadcast on and cut an antenna 1/4 (or smaller) to the wavelengh.

http://k4far.home.att.net/calc.html



the link by discordia is good.. i guess one would want to 'by pass' the battery if you were using this as some sort of rfid.

by saying an antenna is not necessary.. although true in this radio, would totaly depend on what you were using the radio for and how far a transmission you wanted.

also be carefull with your specs on using 12v with the componants you use-- since you can easily destroy them, since most alkaline batteries have more than 10% of the volage when new, than what they advertise themselves to be.



[This message has been edited by Halvy101 (edited 02-09-2007).]

umm..

well see our year was the first to have the elective electronics.. so basically the school went ahead and brought alot of resistors, LEDS, and stuff..

so we want to see what we can use, and what we have to buy..