Working FM Transmitter Circuit

Do your own homework.

Do your own homework. CR4 is not a homework cheat site; however, if you have questions about understanding concepts or how a portion of a problem is derived, these types of questions will be accepted.

You are becoming a pain in the butt.

Learn how to use a search engine.

What frequency are we talking about, standard commercial radio band perhaps?

Was it the circuits that were wrong or did you construct them wrong?

Have you tried fault finding them?

Buy one! They will work. Don't expect them to receive AM helps too.

http://www.analog.com/media/en/technical-documentation/application-notes/AN-543S.dsp

Since this is Analog Devices, there's a pretty good chance their stuff works.

Here's another one you can try.

Good luck with your quest!

You can't simply build a RF circuit from a circuit diagram.

In fact you can't even build a audio hi preamp just from a circuit diagram as I found out about 40 years ago.

If you are a newbie hobbyist, stick to audio, simple logic and low frequency stuff.

Start with something very simple, once you can understand that and make it work, progress to slightly more complicated stuff.

E.G a simple series regulated power supply using discrete components is a good and useful exercise.... you'll learn far more than if you just wire up a 78L05 , mind even that can go wrong with out the decoupling capacitors

Del

Or for $50 you can buy this and be W - A - A - A - Y ahead of rolling your own.

http://www.amazon.com/KEDSUM%C2%AE-Range-Stereo-Broadcast-Transmitter/dp/B00D826PU6/ref=sr_1_15?ie=UTF8&qid=1425578162&sr=8-15&keywords=fm+transmitter

WARNING: These cheap inexpensive units are not plug-and-play. You will probably need to fiddle with them to get good performance.

I have one of these I run at 50 mW so I can 'carry' my music around the house or yard with just a simple FM Walkman or little boombox. They work pretty well provided you're careful with how you route the power cable relative to the audio cable because it will pick up hum very readily. I also added a split ferrite core (two wraps) to the power supply cable to kill the interference that the little switching power supply couples into the transmitter.

I found some unused spectrum down around 88.3 MHz and made sure I was in the low power setting. If I tune my car radio to my 'pirate' radio station, I lose the signal once I am about two or three houses away, so I don't believe I will incur the wrath of the FCC. (What's that clacking noise I hear on the pavement . . . . . ?)

I just got so tired of COMMERCIAL radio with its 8 to 10 minute blocks of commercials. I much preferred the old format where they played a couple of songs, then a commercial, then a couple more songs and so on. Weekends are especially bad on the radio.

Cheers !

You can't simply build a RF circuit from a circuit diagram.

I was thinking he was trying to build one of those short range FM spy bug transmitter circuits that you can pick up on your radio. Those are straight forward to build.

I mean you can't actually physically lay it out like the circuit diagram.

With RF, layout and construction is critical...

But I'm sure you know that, I just suspect the OP doesn't

Del

u should not be ask this type of questions because it is the site to clarify your doubts in concept not to ask the circuit diagram you should search in the search enginr

Thank you brave sir robin for providing ckt. I keep on trying on this.