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Simple SW receiver on 3V?

Discussion in 'Radio and Wireless' started by aurelZ, Jun 21, 2019.

  1. aurelZ

    aurelZ

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    0
    Jun 10, 2019
    Hi folks!
    I was looking into circuit of Shortwave receiver which
    work stable and solid on 3 V...mean 2x1.5V battery.
    I saw many circuits on net and on youtube but most
    of them use 9V battery ,which from my point have small time
    of duration.
    thanks in advance!
     
  2. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    You could just add boost converter like the TL496 to a 9v circuit.
     
  3. Audioguru

    Audioguru

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    Sep 24, 2016
    Short Wave radios were used a long time ago so their circuits are old.
    An old audio amplifier circuit that uses a 3V supply and an 8 ohms speaker will produce only 0.05W of power. As loud as an earphone. When the battery voltage drops to 2V as it is used then there will be no sounds.

    If a radio is designed to use a 3V battery today then it will use a modern class-D bridged circuit in a PAM8403 audio amplifier IC. When its battery drops to 2.5V then its output power will be 0.5W in each of its two 4 ohms speakers.
     
  4. aurelZ

    aurelZ

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    0
    Jun 10, 2019
    -You could just add boost converter like the TL496 to a 9v circuit.
    Hi
    so you think that i can use DC-DC upverter..
    but that would just complicate things.
    Also i mean use fat 1,5V battery not tiny AA or AAA
    so receiver should work long time with low current consumption.
     
  5. BobK

    BobK

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    Jan 5, 2010
    There is no reason a 3V would last longer than a similar sized 9V if outputting the same power. In fact, it might be the opposite unless a class D amp is used.

    Bob
     
  6. Audioguru

    Audioguru

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    Sep 24, 2016
    Batteries have part numbers. A tiny 186 button cell is 1.5V. The 1.5V cells in a 9V battery are AAA. Then the larger 1.5V cells are AAA, AA, C and D.
    You select the chemistry (alkaline?) then their datasheet tells how many mAh they have for their capacity.

    If you want a receiver battery to last for a long time then the current used by the radio must be low or the battery must be large.
    To use low current then the receiver loudness must be low (earphones).
     
  7. aurelZ

    aurelZ

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    0
    Jun 10, 2019
    Ok
    leave aside batteries....
    So is here anyone who can recommend me which type
    of SW receiver to build?
    Regens ...all types are not very much stable
    Maybe Direct conversion are better with and much stable.
    there are too many designs published?
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    1,822
    Nov 17, 2011
    You may have a look at the SI473x chips which operate down to 2 V.
    You will need an additional controller chip (microcontroller).

    I also stumbled across this chip. No separate controller required.
     
  9. TCSC47

    TCSC47

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    Mar 7, 2016
    I presume you are thinking 9V means you will use a PP9 which have a reputation for not lasting. However a modern alkaline PP9 can last quite well, particularly if your radio uses headphones instead of a power amp and speaker. Alternatively you can buy rechargeable PP9 style batteries but they can be pricey particularity if you need to buy a charger as well. Thirdly you could use 6 x AA or AAA in a battery holder if you are not bothered by the bulk. Then you could use any of the 9V designs.

    However, I came across this simple looking receiver which looks nice. It all depends on the performance you want.

    [​IMG]


    http://www.circuitstoday.com/single-transistor-radio

    This design is for the medium wave. No details are given on how to construct the tuning coil apart from it being 0.35 mH and being centre tapped. A bit of research on line will tell you how to wind one for the short wave frequencies.
     
  10. aurelZ

    aurelZ

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    Jun 10, 2019
    Thanks TCSC
    This design is really primitive but should work with not god
    selectivity .
     
  11. BobK

    BobK

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    1,636
    Jan 5, 2010
    That is basically a crystal set with a 1 transistor amp.

    Bob
     
  12. Audioguru

    Audioguru

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    Sep 24, 2016
    The simple circuit is missing sensitivity, selectivity and automatic gain control that every simple super heterodyne AM radio circuit has.
     
  13. TCSC47

    TCSC47

    31
    9
    Mar 7, 2016
    I don't know if this is your first radio build, but being simple it is more likely to be successful. If you want a more sophisticated design, then 9V supply gives the designer more latitude in their design, so I would ask if it really has to be 3V?
     
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