Jump to content
Electronics-Lab.com Community

FM Receiver Circuit


Recommended Posts

Hi Guys

i am zeshan & i just joined "Electronics Lab Community". First of all i would like to thanks to the person who is managing this web site and other for helping each other... i just got a project from my college to build up some thing... i was planning to build a fm tranmitter (i have fm transmitter circuit diagram) but my lecture said you also need to build a receiver (need a fm receiver circuit diagram) as well.. but  unfortunetly i cann't find any fm receiver circuit diagram.. can you guys tell me where i can get fm receiver circuit diagram.

thanks & regard

zeshan

Link to comment
Share on other sites

Oh no! Now the super-regen is here.
On another electronics forum there is a guy who tried many super-regen FM "radio" circuits to find one that works.
1) They are extremely distorted because they don't have an FM detector. They use their AM detector instead and you tune to the side of a station for "slope detection" of the FM.
2) They get cut-off by local stations.
3) They transmit interference to other radios and TVs.
4) It is very hard to adjust their positive feedback.
5) Like similar simple FM transmitters their RF frequency drifts all over the place. :'( :'( :'(

Link to comment
Share on other sites

I think ECET0purdue got the best offer so far and audioguru I agree using slope detection with an am detector is not a good choise.
The TBA120 in the schematic from the link ECET0purdue sent will do the job just fine it's a well know IC for doing this.
This is a narrow band fm reception as the author say, the CFM455 isn't marked with the suffix (A-I) which tell the 3 and 6dB +/- bandwidth of the filter so you have to choose the right one for the bandwidth you wish.
Check http://oh3tr.ele.tut.fi/~oh4mvh/project/muRata_Filters.pdf
If you haven't built any receiver before please take some time to read on the subject.

Link to comment
Share on other sites

zeshanuk didn't say on which frequency the transmitter was designed for.
I would go for a more simple solution like the one in this link:
http://www.mikroelektronika.co.yu/english/product/books/rrbook/chapter4/chapter4c.htm
going to table of contents from this page will give you more to think about :)
There is another link I've found where you can improve your knowledge on the subject and much more: http://hem.passagen.se/communication/ifcan.html

I don't think the shortwave narrow-band radio will work up on the VHF wideband FM broadcast band, to match his simple FM transmitter. Sad


Why not?
Doesn't it depend on the deviation of the transmitter he is going to use?
For speech I think it is just fine.

Link to comment
Share on other sites





Its IF frequency is much too low for the FM broadcast band. It has only a single RF tuned circuit so its image pickup would cause horrible interference from adjacent stations.

BTW, I have two of those "Philips FM scanning radio in an IC" that I got for free, and they are sold cheaply in The Dollar Store. They are lousy! :'(
Link to comment
Share on other sites

Ok audioguru :)
Yes I know that the image rejection is poor cause of the 455kc and single tuned rf amp but it depends where you live, you probably live in a area where the FM band is quite crowded, besides zeshanuk didn't mention the transmitter frequency.
This receiver will work, the only thing you will have to do is to tune it to a segment that is not not to crowded. I think that the only thing zeshanuk wanted to to do is a receiver to listen to his transmission.
Whether it is for speech or music is another question  ;D
There is a big number of receivers that can be used out there, this was only a suggestion to zeshanuk.
Audioguru let zeshanuk know if you got any better alternative.
So what's so bad with those TDA7088T, do you think PHILIPS make an IC that is so bad that you can't listen to a tiny little home made fm TX??  ;D
I think there is no receiver in the world that is the perfect one, all depends on the demands you have, right?

Link to comment
Share on other sites


So what's so bad with those TDA7088T, do you think PHILIPS make an IC that is so bad that you can't listen to a tiny little home made fm TX??

It fades on even strong local stations and doesn't pickup weak ones. It scanned right past my powerful FM transmitter so will also miss his weak one. It is very noisy and distorted.
Also, I don't think a nubee would be able to solder the tiny multi-pin surface mount IC. :(

There might be a simple broadcast-FM radio project on the web that uses the proper 10.7MHz IF frequency.
Harry is a Ham Radio Operator so he makes short-wave radio projects with 455KHz IFs.

Yeah, my FM band is completely full. I had to test my transmitter on the same frequency as a foreign-language station on the other side of my city.
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...