FM Transmitter & Receiver

[Suds]

Hi

I was wondering if anyone has a simple FM transmitter and a seperate (also simple) receiver circuit schematic. I just need to make my room speakers wireless so max range would not be more than 10m.

Thanks in advance

 

[bananasiong]

There are so many FM transmitter schematics in this forum. For the receiver, you can just use a radio. Or you can use TDA7000 FM radio circuit. Or you can search for super regenerative receiver.

 

[Hero999]

We have 100s of FM transmitter threads, for future reference, it's always a good idea to search the forum before asking.



Just use a cheap FM radio for the reciever, it will work out more expensive for you to build your own.

 

[audioguru]

A simple FM transmitter's frequency drifts all over the place. Its sound quality is horrible. It is a child's toy.

A cheap radio is about as bad or is worse.

 

[chemelec]

There are so many FM transmitter schematics in this forum. For the receiver, you can just use a radio. Or you can use TDA7000 FM radio circuit. Or you can search for super regenerative receiver.

Here is a Reasonably Good, VERY CHEAP FM Reciever.
(Especially for only 99 CENTS)

https://www.goldmine-elec-products.com/prodinfo.asp?number=G15657

 

[audioguru]

Here is a Reasonably Good, VERY CHEAP FM Reciever.
(Especially for only 99 CENTS)

It is crap!
I got two complete scanning FM "radios" with built-in flashlights and earphones for free by signing a contract to receive a newspaper for a few weeks.
The two cheap AA cells they came with actually worked.
The "radio" has terrible sensitivity and its sound drifts in and out with strong local stations. It has built-in muting that mutes most stations.
It sounds bad but the earphones sound great on a CD player.

It uses a Chinese copy of a Philips lousy FM "radio" IC.

 

[mvs sarma]

Hi

I was wondering if anyone has a simple FM transmitter and a seperate (also simple) receiver circuit schematic. I just need to make my room speakers wireless so max range would not be more than 10m.

Thanks in advance

by the type of request, it is clear that Suds needs a stereo transmitter. the best appears to be either using BH1417 (eg., Micromitter) or BA1404 (see the application notes)

Rx can be any stereo receiver. you are likely to get good quality for few bucks. it coud be incorporated into the particular speaker having the amplifier while the other spkr gets the amplified audio thro a cable interconnected. the radio can possibly be powered by the internal PSU of the streo speaker sysytem (Amplispeakers)

 

[Hero999]

audioguru's transmitter isn't that bad and a better idea is to buy a cheap radio and rebuild it to a quality design with some extra components.

 

[audioguru]

A real FM radio has many tuned circuits or crystal filters and an IF frequency of 10.7MHz with lots of gain. The el cheapo FM radio in a single IC uses a 70kHz analog filter made with an opamp for its IF amplifier.

The real radio tunes its input before its RF amp to avoid overload and to increase selectivity. The el cheapo one doesn't tune its input, its input sensitivity is reduced to reduce overload.

The real radio has automatic gain control on its RF amplifier to avoid overload. The el cheapo one doesn't.

It would be very difficult to turn the el cheapo into a real radio.

 

[mvs sarma]

audioguru's transmitter isn't that bad and a better idea is to buy a cheap radio and rebuild it to a quality design with some extra components.

Hi Hero999,

No second thought in the perfectness in MOd4 design- Really Audiguru has optimized it. you can find on this and other forums, i do suggest only this design across other posts searching for FM TX.

I only suggested that , as SUDs wanted remore audio signal for his room speakers, i felt that anyone now a days need a stereo signal for the room speakers.

in sucha context, i suggested BH1417 based TX.

 

[Gayan Soyza]

For FM receivers I normally use CXA series (SONY).

 

[audioguru]

I think my cheap Sony Walkman FM stereo portable radio uses the CXA series IC. It is pretty old, about 15 years and its sensitivity is not very good. It overloads with strong local stations so it has a local-distant antenna attenuator switch.