FM Radio

[EDY]

Hi Mike (and everyone else)
First of all I have to say that site rocks   You

[mixos]

The IC3 = LM386 is a low voltage audio power amplifier. It's voltage gain can be adjusted between 20 and 200 with the external parts. So you can remove it and drive the speaker with your own audio amplifier.

[AVRFreakMan]

Hello EDY,
you are correct. IC3 and its complementary componets are a just a sound amplifier and can be ommited. You can put the sound signal (taken from potensiometer's P1 wiper) directly into your's soundcard AUDIO input so that you can have totally digital control over your radio receiver.
(You realise ofcourse that tuning isn't exactly 'digital' but looks like it )  )

The DOS software I have, is very old technology and has several bugs. If you want to look for something else, search for any freeware Parallel Port access tool on Google. You should find something...

Kyriakos

[EDY]

Weel it says it can be connected to the PC on the schematics but that isn't my goal. Just want to build a simple fm reciver.
Theres one thing bugging me.
In my car's radio you can chose between low and high pass (not sure is this exactly the term) but I havent seen it on any schematics.
I'll look the car radio later and tell you the frequencies it has.
P.S. it has AM parto so don't think I'm talking about that

[AVRFreakMan]

Ok, you may use it as a simple analog radio receiver  

About the other matter, the "low-high pass", I can only guess for what you are talking about. I think you mean "tone control" which suppress or raise the low-high frequencies of the acoustic bandwidth.
Well this receiver doesn't have any of these 'whistles' because of it's simplicity. It is a mono (not stereo) FM receiver.

[EDY]

Actualy you havent guessed. Most probably becouse I made a stupid explaination of what I ment . I found the answer in one of philiphs FM radio chips
But tanx anyway

[Wilson]

Hi,
I build the FM Radio on a proto-board and I used a BB204B variable capacitor instead of BB329, but it didn't work. Anyone could tell me what modifications do I need to do in order to use the BB204B.
Thanks for any comment!
Wilson

[mayo]

Hi:
Any has asembled this FM Radio with BB105 diode, I use this but dont work. Are shematic and components correct?
(I hear noise but dont any radio).
Thanks.

[AVRFreakMan]

If it cannot tune to any station, experiment with the coil. Stretch it, add more rounds...

[mayo]

Dear AVRFreakMan:

Is correct, I cant tune any station. I will esperiment with coils.
What coil define tunning frecuency? L1 o L2?

If the radio is out of the comercial frecuency, How I can know if the radio is working and if the problem is only the coil?
Anybody know the value of the coils (uHy - mHy) ?

Thanks.

[AVRFreakMan]

L2 is the tuning coil.
Just make it: take a thin wire(0,6mm) and make 5 turns of 4mm internal diameter.

If it doesn't work try to stretch/squeeze it and if it doesn't work add/remove turns and repeat.(adding turns reduces frequency).

If no success, check the PCB and components for errors, or use a capacitor trimmer instead of the varicap, or search the internet and the datasheets of TDA7000 for other similar circuits.

Kyriakos

[ahmedhussain]

Hey,

Please tell me the equivalent in MicroHenry [uH] of "5 Coils linked with internal diameter 4mm from cupreous isolated wire 0,6mm" of inductor used in thsi project.

Also, please tell me that can we use the above inductor in equivalent Henry or we must have to make the inductor by ourselves.

Also, please tell me the lenght in cm of the inductors used in this project.

Thank you very much

Ahmed

ahmedhussain85@yahoo.com

[audioguru]

Hi Ahmed,
Welcome to our forum.
The IC hasn't been made for years. Where did you get one?
The coil is simple to make, if you buy one then you won't be able to adjust it. Just make it and adjust it like explained above.

[ahmedhussain]

Sir i think u dint actually get my point. There are 2 types of inductors.

1.  That u make urself by using a wire of a certain lenght n thickness and making
ciols of it.

2. That u can get if u know the inductance of an inductor like 10uH, 0.1uH, etc. It looks just like a resistor. It does not have any coils.

The function of both is the same. I tried both while i was making FM transmitter. But only 2nd one worked. So, I just wanted to know if it is necessary to use a handmade inductor or we can use the one that looks like a resistor ( I dont know what to call it )

Thanks