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Simple AM Radio Receiver

Discussion in 'Electronic Projects' started by transistor495, Jun 14, 2009.

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  1. blueroomelectronics

    blueroomelectronics Well-Known Member

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    What radio are you referring to?
     
  2. nike6

    nike6 Banned

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    the one in the picture attachment, on the first thread page, two photo's.
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Are you trying for the 'most stupid post of the year award'?.

    And for someone who claims to be from Ireland, why keep quoting prices in dollars?.
     
  4. dave

    Dave New Member

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  5. nike6

    nike6 Banned

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    most of the visitors are from the US?

    It is a standard currency. I buy many parts using US currency, for instance Hong Kong.

    I don't understand what you are trying to say about the radio.
    I found it very useful as a light source for making Macro photo's,
    or to observe my ants in the evening.

    initially i also wrote the price in Euro's, €4.49

    the crap of the year award goes to:

    -key fob LED lamp, contacts quickly oxydizing, and replacement batteries costing more than a new lamp

    -solar cell LED lamp, falsely claiming that it is rechargeable, but does not charge at all (guess a fake lithium cell, not an accumulator).
    cost: 17 Euro's.

    there are numerous crap products, indeed, but this radio is not so bad.
    I was also thinking of a SONY radio for about 20 Euro's, pretty much retro style.
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It's a VERY worldwide forum here, I wouldn't say most visitors are from the USA.

    Have you no pride in your own currency, or do you still not consider the Euro 'your' currency?.

    Sorry, but it's absolutely rubbish - you only need to look at it, or even just look at the price :D
     
  7. nike6

    nike6 Banned

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    Ok i was thinking I do people a favour so they do not have to mess with our Euro.

    I do not know the word "pride".

    also you may not know the purpose for which i intend to use the radio - particulary, to test metal detector circuits.
    It may serve this purpose very well.

    also it turned out to be a great helping for macro photo, previously, I had great difficulties with that.
    the camera software is focussing on the bright spot, as intended.

    yes having ants in the house may not be everyone's cup of tea.

    but as for Radio, i do not really listen to stations. maybe i also want to buy that SONY radio.
     

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  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    So how does that alter the fact that it's a crap radio?.

    It may work perfectly well for your somewhat obscure requirements, but that doesn't make it a 'good' radio - only that your requiremnts are very undemanding.
     
  9. Hero999

    Hero999 Banned

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    I see no radio, the picture in your last post is just a load of ants feasting on syrup.

    What's your point?
     
  10. mvs sarma

    mvs sarma Well-Known Member

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    if you don't listen, what it matters, you can go with the present one, so that the ants can also co exist with in the radio, perhaps using it as a storage for their conserved food
    Perhaps a SONY ICFSW-7600GR with digital scale and all newer facilities like SSB, with a possibility to mod for DRM reception in Short and Medium waves, (http://www.electro-tech-online.com/custompdfs/2009/06/Sony_ICF_SW7600GR.pdf ) may not be liked by the Ants--
     
  11. nike6

    nike6 Banned

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    Ehm
    http://www.electro-tech-online.com/threads/simple-am-radio-receiver.94129/#post754206

    ╔╦╦╦═╦╗╔═╦═╦══╦═╗
    ║║║║╩╣╚╣═╣║║║║║╩╣
    ╚══╩═╩═╩═╩═╩╩╩╩═╝

    yes it is crap - that old 1980s ASCII.
    it may server some purposes pretty well.

    and the ants yes, they came to me, not the other way round.
    they now also feel free to explore everywhere, and end up inside drinking glasses.

    *** EDIT

    here the PCB of that SONY AM/FM tuner.
    cheaply made but at least two TOKO's, and one 455 KHz filter.
    after reading the thread, I now feel comfortable to take it apart,
    and to extract the tuning capacitor.

    anyone knows more about the pin connections?
    there are also various small trimmers inside these var.-cap's
     

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    Last edited: Jun 20, 2009
  12. transistor495

    transistor495 Member Forum Supporter

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    Ants does exist in every radio receivers regardless of SONY or GRUNDIG whatever it is, see MW ant in the circuit. Other types ants include:

    LW ant
    SW ant
    FM ant
    CW,SSB high grade ants..
     
  13. transistor495

    transistor495 Member Forum Supporter

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    Updates!

    Nike I missed you..:(

    Here's more details about the antenna, tuning cap and RF Choke for complete beginners for a total success ;)

    Avoid trimmers if not using a meter dial.

    Using a large loop antenna increases the sensitivity much more!
    AM Loop Antennas

    I've made one same like this using PVC joint frame..visitors asked me whether I've constructed a transformer lol :D

    [​IMG]

    Construct it and go back to 1960's. Enjoy and Good luck!
     

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  14. kindaboy2010

    kindaboy2010 New Member

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    Hi transistor495 thx 4 great effort and i hope the circuit work :D

    I have question 4 u can u tell me what is the benefit of 4148 above the transistor BF494 and where exactly the ED in this circuit.
    (SORRY if i ask stupid QUES. iam a beginner :eek:)
     
  15. transistor495

    transistor495 Member Forum Supporter

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    kindaboy,

    It's a kinda circuit where the transistor BF494 works on both RF and AF mode at the same time. So is called a 'reflex receiver'. We take benefit by avoiding 1-2 transistor pre amplifier stages where the aim was to make it simplified yet keeping a good level of sensitivity/selectivity and audio quality.

    The radio frequency waves caught by the antenna amplified by the transistor and appears at collector, from there 4148 along with 472p cap demodulate it and an audio appears at base of the transistor which is again goes for further amplification along with RF waves. This process repeats and we get amplified RF and AF at collector, which is inputted to the inductor L which acts like an RF Choke. So it blocks high frequency radio waves and only allows passage of audio frequencies through it. 472p at the output of L bypasses any unblocked RF. So we get a clean audio output at C and it is given to the power amplifier for driving a Loud Speaker.

    RFC is a tricky part in reflex circuits :)
     
  16. kindaboy2010

    kindaboy2010 New Member

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    transistor495

    thx soo0oo much 4 ur help

    PLZ can u give me just last 2 hints
    1) what is 180E ????
    2)I want to be communication system designer so any references u
    Preferred can help me in my path :p

    And thx a gain 4 ur help
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    180 ohm - I think the 180E maybe Dutch?, as it's used in the Dutch magazine Elektor.
     
  18. mvs sarma

    mvs sarma Well-Known Member

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    we generally use R or E to indicate ohms
    if they are fractions 3R3 or 0R1 are also used
     
  19. kindaboy2010

    kindaboy2010 New Member

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    THX alot 4 help
     
  20. transistor495

    transistor495 Member Forum Supporter

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    'Secrets of RF circuits design' is a good tutorial on this stuff.
     
  21. transistor495

    transistor495 Member Forum Supporter

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    Some pics

    The original prototype of this circuit is built neatly on an ultra small package, unfortunately I doesn't own it now. However for taking pictures, yesterday I attempted a 1/2hour taken dirty assembly with all components ready in hand.

    Only valuable component on the pcb is the audio amplifier IC, which I'll pull out later for other purposes and kick the pcb out.

    It works great anyway..:confused: ;)
     

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