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AM receiver

Discussion in 'Datasheets, Manuals and Component Identification' started by silver est, Apr 6, 2012.

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  1. silver est

    silver est

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    Apr 6, 2012
    I am trying to make a very simple amplified am radio receiver. I tried it and it didn't work.
    If you have any suggestions then please help me with this.
     

    Attached Files:

  2. timothy48342

    timothy48342

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    Nov 28, 2011
    What kind of transistor is that? (something doesn't seem right with the transistor and/or the battery.)
    Where did you get the schematic? Do you have a link? Or is this your design?

    -tim
     
  3. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    A battery is normally connected in the collector circuit, not the emitter and in any case the polarity is such that it turns the transistor off.

    The diode is not necessary, the emitter/base connection of the transistor will do this. You will need 0.7V to turn on the transistor and 1.4V to turn on the diode and transistor. It is difficult to get this voltage from the antenna. You could use a germanium diode (0.2V) and AC couple this to the transistor.
     
  4. War_Spigot

    War_Spigot

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    Feb 20, 2012
    I think the + of the battery should be connected to the collector and the pot&speaker connected to the emitter
     
  5. silver est

    silver est

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    Apr 6, 2012
    Thx duke
     
  6. silver est

    silver est

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    Apr 6, 2012
    And yes the transistor needs atleast 0.7 v to turn on, thats why the battery was here.
     
  7. silver est

    silver est

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    Apr 6, 2012
    Sorry I am not very good at this, what means couple( as a verb ). And where could i put the power source, battery which should grant that the transistor is always over 0.7 v and anything that comes from the antenna will be amplified.
     
  8. silver est

    silver est

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    Apr 6, 2012
    I made a new one from my own logic: [​IMG]
    And one from your suggestions:[​IMG]
    What is are the polarities of the npn transitor?
    -sorry im stupid at this
     
  9. silver est

    silver est

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    Apr 6, 2012
  10. silver est

    silver est

    20
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    Apr 6, 2012

    Attached Files:

  11. War_Spigot

    War_Spigot

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    Feb 20, 2012
    I think, if that website is correct, that first one is correct. However, I think the battery's voltage(the one connected to the speaker) will have to be more than 1.5V. Be aware that this will also invert it. I don't know if that has any affect on the sound output, but I don't think it would.
     
  12. davenn

    davenn Moderator

    13,669
    1,891
    Sep 5, 2009
    the second one looks better but I doubt that there's enough signal from the single transistor to drive a speaker. An earphone would be more suitable..

    Anyway there's a huge mass if circuits available on the net that are much better designs eg......

    http://www.extremecircuits.net/2010/06/simple-am-radio-receiver_13.html

    http://www.circuitstoday.com/am-receiver-circuit-using-mk484

    http://circuitdiagram.net/am-radio-receiver.html

    http://www.circuitdiagram.org/simple-am-receiver.html

    there's 4 samples for a start :)

    cheers
    Dave
     
  13. silver est

    silver est

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    Apr 6, 2012
    Content Deleted
     
    Last edited: Apr 8, 2012
  14. silver est

    silver est

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    Apr 6, 2012
    Content deleted
     
    Last edited: Apr 8, 2012
  15. silver est

    silver est

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    Apr 6, 2012
    Anyone has idea how to make it so that no ground is needed?
     
  16. silver est

    silver est

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    Apr 6, 2012
    I tried the number four schematic, it went hot after some time. I think the reason for that was I used one 2 battery pack, so they were all connected, I will put them seperately and see what happens. And I still don't undersstand why should the thirt schematic work.
     
  17. silver est

    silver est

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    Apr 6, 2012
    I dont think the second one would work because the transistor needs atleast 0.7v to be in active stage and I don't think radio waves will give it 0.7v.
     
  18. davenn

    davenn Moderator

    13,669
    1,891
    Sep 5, 2009
    the second one is the best of all !! :)

    do a google search on the MK484 IC and you will be suprised what it actually does

    The MK484 is a later version of the ZN414 that I played with 40 yrs ago in my teenage yrs

    Dave
     
    Last edited: Apr 7, 2012
  19. silver est

    silver est

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    Apr 6, 2012
    Sorry, we have a misunderstanding.
    The problem is that you are talking about the links you gave me and I :D
    am talking about the schematics I made. Really sorry for that.
    Hope you can help me with my own circuits.
    I will now delete all the posts I made with misunderstanding.
    -------------------------------------------------------
    How should the transistor with a needed bias voltage of 0.7v turn on with below 0.001v from radio waves? Thats why the battery was there in first one to make sure the transistor is in active stage. If the transistor is not in active stage IT WILL NOT FUNCTION. Sorry if I have misunderstood anything. I just need an explanation not which one is better.
    Thank you for the MK484 I will take a look at it soon.
     
    Last edited: Apr 8, 2012
  20. silver est

    silver est

    20
    0
    Apr 6, 2012
    I don't know how it's called but I want to make everything myself, or atleast with full understanding of how a thing works.
     
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