FM-Stereo-Radio ?

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hariskar

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Joined 2015
#1
diy FM-Stereo-Radio ?

I am not experienced with diy, but want to try this FM-Stereo-Radio
Here you can see a video of this.

The description in German is quite detailed and I know that the main difficulty is configuring L1, L2 and the trimmers. But I want to try it. I will keep you informed!
 
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#3
hariskar said:
I am not experienced with diy, but want to try this FM-Stereo-Radio
Here you can see a video of this.

The description in German is quite detailed and I know that the main difficulty is configuring L1, L2 and the trimmers. But I want to try it. I will keep you informed!
Click to expand...

Think about using a proper 9v DC supply, as the circuit will soon dissipate
the small amount of current that style of battery has - usually somewhere between
100-300ma. Voltage then drops, followed by the ability of the circuit to function.

Cheers / Chris
 
#4
I have build at least 5 of these :
http://www.diyaudio.com/forums/analogue-source/8089-fm-am-tuner-3.html#post2239643
https://www.elektormagazine.com/magazine/elektor-200902/18989
https://www.elektormagazine.com/magazine/elektor-200904/19020

Same chip set. Coil is very easy to wind.
If you have to drive londspeakers thn you just change the output chip.
See the application circuits in the TDA dataheets.

TDA 7021 T SMD: FM Radio-Circuit, SO-16 bei reichelt elektronik
TDA 7040 T SMD: Stereo Decoder, SO-8 bei reichelt elektronik
Drehkos

Great sound.


Patrick
 
#5
Chris Daly said:
Think about using a proper 9v DC supply, as the circuit will soon dissipate
the small amount of current that style of battery has - usually somewhere between
100-300ma. Voltage then drops, followed by the ability of the circuit to function.

Cheers / Chris
Click to expand...

Yes, I was thinking that too. If the rest succeeds I will do this.
EUVL, if this point to point circuit fails, I will try these PCBs.

Thank you for replies!
 
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#6
I wish to add that :

1) There is no need to use a capcitor diode to tune, just a normal variable capacitor will do.
I even used a trimmer capacitor myself.

2) There is also no need to use a uP to indicate signal strength.
Just follow the circuit in the TDA7021 datasheet. Much simpler.

3) If you use the TDA7050 or LM386 to power speakers, you can use a single 4.8V to 6V supply (batteries or rechargeables).
For headphones also lots of choices, e.g AD8532, LM4910,......


Patrick
 
#7
It does not matter whether you wire P2P or use PCB.
Take time to study the dataheets and note the differences to your reference circuit.
You will see why the Elektor / Datasheet circuit is simpler.

And use proper mica or polyproplyene caps, not ceramics.
Makes hugh difference to sound quality.


Patrick
 
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#8
EUVL said:
It does not matter whether you wire P2P or use PCB.
Take time to study the dataheets and note the differences to your reference circuit.
You will see why the Elektor / Datasheet circuit is simpler.

And use proper mica or polyproplyene caps, not ceramics.
Makes hugh difference to sound quality.


Patrick
Click to expand...

I would suppose that the components of PCB would be preconfigured and almost ready to use in contrast to the p2p circuit (I am referring especially to the inductor L1).

Any good caps suggestion? There are hundreds of choices for each impedance..

Thank you
 
#9
That depends what you want to do.

If you want quick results then the quicket is to buy a FM stereo module from ebay.
Plenty of choice for a few Euros.

If you want to enjoy DIY then you might want to either P2P or etch your own PCB.
It is the (full) experience that counts, not the effort.

For leaded caps I use Wima MKP2 & FKP2.
Silver mica's were from Reichelt, but also available from Mouser, etc.
If you want to use SMD then Panasonic ECHU (PPS).

Inductor L1 you need to wind yourelf.
See Elektor article.


Patrick
 
#11
hariskar said:
I would suppose that the components of PCB would be preconfigured and almost ready to use in contrast to the p2p circuit (I am referring especially to the inductor L1).

Any good caps suggestion? There are hundreds of choices for each impedance..

Thank you
Click to expand...
One that compensates for small changes in the tuner's operating temperature. Otherwise the tuner frequency drifts off as the tuner warms up.

I had a commercial tuner in a car amp that was not properly temperature compensated. I paid a repair specialist to fix the tuner.
I think he simply replaced the tuning cap, or some such, with exactly the same. The warm up behaviour ended up exactly the same. Even a readjustment after 20minutes still needed a further adjustment to get rid of the mistuning distortion.



Mixing a proportion of N150 with an NP0 may give adequate temperature compensation. The difficult bit is getting the proportions about right.

The best car FM tuner I ever had in a car was a Blaupunkt Frankfurt dedicated tuner (it only did FM, no AM), not the later Frankfurter integrated tuner amp, which was far inferior.
 
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#14
There is no need to go to the JLH circuit unless you really want to understand HF circuits and build discrete.
http://www.diyaudio.com/forums/analogue-source/134795-john-linsley-hood-fm-tuner-article-s.html
And the Linsley Hood circuit also uses ICs which are no longer available (easily).

If you really want to build discrete, then this is as discrete as one can get :
UKW-Projekt
UKW-Mischteil_mit_EF95_von_Jochen_Becher
UKW-Dekoder

But for a beginner, the TDA7021 is a good starter.
Simple enough to build even P2P, but great sound.


Patrick
 
#19
Hi again,
I don't but have not tried to located any.
Ryder seems to have followed the sanyo data sheet mostly and the LA1235 sheet suggests a second source from Toko Q228Cel-1077B. Here are some exploration paths…
1) sumida is still in business, but dealing with Japanese firms in english is not easy.
2) search resellers of obsolete parts for the Toko or sumida part including ebay.
3) LA1235 was used in several tuners, steal one from another tuner. tuners from 1985+, it is a good part so the tuners will be fairly good ones.
4) try to replace with two individual coils instead of this rare 2-element in 1 case. I've seen it done in some tuners that use the LA1235. In fact I would look at all the tuner schematics that use the LA1235 for alternate options.
5) read this blog Modern take on Ryder’s FM Receiver | Blog1

cheers
paba
 
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