Simple Radio Circuit

Discussion in 'The Projects Forum' started by Art, Mar 3, 2010.

  1. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Simple Radio Circuit <- Yeah Right!!! That's what it's supposed to be!

    Hi Guys,
    Would anyone share a schematic for a AM or FM radio they have actually made from
    easily obtainable parts?

    I have tried Jaycar Short Circuits FM radio kit,
    Dick Smith Funway 2 Pocket transistor radio x 3
    Dick Smith Electronics 30 in 1 Electronics Kit (has a radio).

    None of these really worked, except the Jaycar FM radio made some squealing noise.
    I don't want to have to run a ground wire to a tap, and I have a 1 Watt amplifier ready
    to use with it.
    Cheers, Art.

    Also a question... Here is the Jaycar FM radio kit:
    http://www.jaycar.com.au/productView.asp?ID=kj8238

    I built it on a prototype board because I didn't want the amplifier chip in the circuit, and a radio is to be only part of a bigger project.
    Would it be an issue that one of the 2 coils are mounted about 5cm from the chip (instead of about 1cm on the supplied PCB)?

    Jaycar FM Radio kit:
    [​IMG]

    DSE 30in1 Kit AM Radio:
    [​IMG]

    The coil L1 on the FM radio is formed on the PCB. It's not actually a coil,
    but a snake like pattern. The dimensions match very closely what was printed
    on the supplied PCB.

    I think the AM radio kit works, but is just unsuitable, and I can't hear any stations in a city area.
    It clicks if I short a 1.5 volt cell near it.
    I would be pissed if I'd paid $29.95 this for my kids (don't actually have any though).
    And don't get me wrong, I had a working crystal radio when I was about ten, and loved my 200-in-1 kit.
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    What is it with people soldering the components onto the solder side of a board?? Pins are supposed to go through the other side and soldered onto the copper pads on the other, this will give the components some "strength" so they won't easily get torn off..... plus it would make a much neater looking circuit....;)... But I doubt that has anything to do with your circuit not working...:rolleyes: but it could be from all that extra stray capacitance you have in all those wires.... which would vary the frequency quite a bit especially for a radio receiver..... see how they have all the components close to the IC on their kit?? Short traces would help quite a bit....

    [​IMG]

    My .02
     
  3. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Don't look at this then:
    [​IMG]

    So you think that is the problem? Lucky I socketed the IC,
    I'll probably try again.
     
  4. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    I got the DSE AM radio kit working.
    I'd still like to make an FM radio PCB.
     
  5. bertus

    Administrator

    Apr 5, 2008
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  6. gizmoman0

    New Member

    Jan 21, 2010
    26
    1
    lol Art why the hell are you soldering like that? those are all through-hole components
     
  7. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Funny I get asked this every time.
    Mainly I like to see everything on one side,
    secondly, I like to place the device on a desk with a flat side.
    Also makes mounting in enclosures easy... no PCB spacers required.
     
  8. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Yay! I got it!! :)

    [​IMG]

    Made a few errors late at night and had to find them the next day, but works great in the end.
     
  9. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Congratulations.

    Is this AM/FM?

    If so what chip did you use?
     
  10. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
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    This is an FM radio based on the TDA7000 (Philips).
    The first picture in this thread is my first attempt at it (non working).
    I made an AM radio as well based on the MK484.

    Someone else has got the TDA7000 going on a veroboard before:
    http://www.amerc.ac.uk/documents.php?action=get&id=38
    It's not trivial. I think mine is at least as nice as that.
    I didn't have to wire any components over the IC.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    looks much "better" :rolleyes: than the first..... good to hear you got it going...

    B. Morse
     
  12. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Thanks. I was looking for AM /FM with digital tuning. I wonder if one exists??
     
  13. redlight000

    Member

    Feb 26, 2010
    66
    2
    Hi Art,

    I think your soldering with all those components is very good, Ive done through hole like you, but I must admit I dont like soldering at the best of times.. :eek:

    But very well done on that effort.. & you got your Radio going.

    keep it up..
    Im impressed.
    regards
    redlight.
     
  14. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Thanks :)

    It's become part of a talking clock radio which is microcontroller driven.

    Finally a project I will actually use :)
     
  15. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Last edited: Mar 14, 2010
  16. retched

    AAC Fanatic!

    Dec 5, 2009
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    Beautiful work. and well done. Are you going to implement the led matrix to the clock output? It would work well if you had to solve four lines of tetris before the alarm could be shut off. :) Or you would just end up with a broken clock on a bad morning. ;)
     
  17. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Lol... this one is a bit of a Frankenstein.
    At least I kept the Tetris hardware simple ;)
     
  18. retched

    AAC Fanatic!

    Dec 5, 2009
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    You do good work. Except for your odd-side soldering ;)

    kidding.. Good work.
     
  19. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    Shoot, you might as well go for surface mount, since you're doing it already. :D

    When I first started my radios when I was a teen lumber was my favorite substrate.
     
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