Questions about Electronic Sound of Chirping Canary circuit?

Discussion in 'General Electronics Chat' started by samy555, Dec 14, 2015.

  1. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
    Hi

    From: http://www.zen22142.zen.co.uk/Circuits/Music/canary.htm

    [​IMG]


    Q1) How do I know that my audio transformer is 1K : 8R? Is it by simply measure the DC resistance?


    Q2) If I wanted to use a ferrite core, how much should the number of turns for the primary and secondary coils, and will this core be simply a rod or one removed from a computer power supply?


    Q3) How the above circuit operates? I know that the transformer is for impedance matching between the transistor high impedance and the low one of the 8 ohm speaker. Also I know that the transistor operates as an oscillator and I understand that the 47K resistor biasing the base of the transistor to start oscillating. Finally I know that the R1+C1 have a close relation to the tone frequency,,,, But what I don't know is the function of the two small caps 10n and 22n and why they have a very small capacitance related to the other two 100u caps.

    Thank you very much
     
    RRITESH KAKKAR likes this.
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,010
    3,785
    You should buy this transformer, not make it. They are commonly available

    See answer to Q1 above

    What did the guy at zen.co.uk say? He posted the circuit, so he should be your first source of information.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
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    Its a modified Hartley oscillator, the inclusion of R1 C1 ensure the oscillator shuts off fast, and C1 discharges through Q1, producing the chirping sound.
     
  4. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
    NO No No

    Oh dear, I do not want to buy this transformer even if the price was one cent
    I'm here to discuss scientific issues and is not going to receive tips out of context
    When you do not have an answer to the question: it is better to not answer
    I know and read what the author said about his circuit
    thank you
     
  5. hp1729

    Well-Known Member

    Nov 23, 2015
    1,948
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    Please do let us know how satisfactorily this circuit works.
     
  6. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
    75
    1k:8 ohm transformers are usually advertised as such. It's a selling point for use in audio outputs.
     
  7. DickCappels

    Moderator

    Aug 21, 2008
    2,651
    632
    Your questions about the design of the transformers are open questions -there are many other variables than the number of turns, though the number of turns is a key parameter. You might learn a lot by visiting the websites of some of the transformer core manufacturers such as Magnetics, Inc., Fair-Rite, TDK, Ferroxocube, Metglas Inc., NLMK (pdf file), ATI Grain-Oriented Electrical Steel, plus there are many more that you can find easily.

    Maybe the two design resources below will be of some help.

    Audio Transformer Design Manual

    How To Wind Your Own Audio Transformers
     
    samy555 likes this.
  8. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
    The transformer turns ratio is the answer.

    N = Np/Ns = turns ratio

    N- the turns ratio
    Ns - is the number of turns on the transformer’s secondary winding
    Np - is the number of turns on the transformer’s primary winding

    So the relationship to the resistance can be calculated as:

    Zp/Zs = (Np/Ns)^2

    So for your case
    1kΩ/8Ω = 125 ---> N = √125 = 11

    No, you cannot use it. The ferrite cores without air gap want work here, also the losses in the core will be quit big for such a low frequency. Because the ferrite cores are optimize for high frequency circuit.
    e02.jpg

    C1 - gives only this "chirp" sound.
    10nF and 22nF set the "high" frequency tone.
    http://mmcircuit.com/understand-rcc-smps/
     
    Last edited: Dec 15, 2015
    RRITESH KAKKAR, samy555 and absf like this.
  9. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
  10. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
    2,831
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    hello Jony130,
    what is this chart for?
     
  11. samy555

    Thread Starter Active Member

    May 24, 2010
    116
    3
    To create a Sound of Chirping Canary
    it works as a house ringer
     
    RRITESH KAKKAR likes this.
  12. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
    2,831
    89
    I don't understand the chart code?
     
  13. hp1729

    Well-Known Member

    Nov 23, 2015
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    Does it sound much like a canary?
     
  14. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,530
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    It's not bad, especially considering the parts count. There is an audio file on the website.

    ak
     
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