Hartley oscillator simple project help

Discussion in 'The Projects Forum' started by leonheard, Jul 5, 2014.

  1. leonheard

    Thread Starter Member

    Jan 8, 2013
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    0
    Hello!

    I need help for my next project... I want to build an hartley oscillator with a resonant frecuency of 9khz
    My power supply has 5.2 volts, my LC tank circuit is tuned to resonate at 9 khz ( no problem there I made the taped air coil about 14.15uH and 22uF capacitor) BUT what would be the values for
    R1,R2,R3,R4
    C1 = capacitor emisor
    C2 = capacitor output
    C3 = capacitor base


    Here is the link of that hartley oscillator….
    http://www.electronics-tutorials.ws/oscillator/osc6.gif


    I have basic knowledge in electronics
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,809
    1,105
    Where is the tap in relation to the coil ends? Half way between, or ....? Is your 22uF cap non-polarised (since the voltage across it is alternating)?
    You could try R1=10k, R2=4k7, R3=2k2, R4=1k, C1=1u, C2=100nF, C3=100nF. However, I couldn't get a simulation of the circuit you posted to work with the coil tap grounded directly. It needed to be grounded via a >1uF cap instead.
     
  3. leonheard

    Thread Starter Member

    Jan 8, 2013
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    0
    Where is the tap in relation to the coil ends? Half way between, or ....?


    its in the middle.

    Is your 22uF cap non-polarised (since the voltage across it is alternating)?

    it is actually an electrolyte :/ i guess i will need to buy a non polarised one...


    However, I couldn't get a simulation of the circuit you posted to work with the coil tap grounded directly. It needed to be grounded via a >1uF cap instead.


    Thanks! I didnt know that, how did you know that a >1uF cap needed to be used? :D


    I couldn't get a simulation of the circuit you posted to work

    Could you tell me the name of the simulation u use?
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,809
    1,105
    Trial and error. That's the beauty of simulation :).
    I use LTspice (as do many on this site), a free download from Linear Technology.
     
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  5. leonheard

    Thread Starter Member

    Jan 8, 2013
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    Trial and error. That's the beauty of simulation



    I thought you used maths, formulas etc lol xD

    I use LTspice (as do many on this site)

    wow! i have that software, i used only 1 time since i didnt know how to use it :p but now i will learn and use it more often.

    Thanks for the help!
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,809
    1,105
    Recommended. Well worth the effort. It takes a while to get familiar with it, but there are good examples supplied, comprehensive Help, and a Yahoo LTspice user group for further help and free additional model libraries to download.
     
  7. RichardO

    Well-Known Member

    May 4, 2013
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    385
    14 uH is an awfully small amount of inductance. I would increase the inductance of your coil and reduce the size of the cap.

    I would shoot for a maximum capacitor size of about 1 uF. This allows using a high quality polyester film capacitor. A 1 uH cap would need about 300 uH of inductance to resonate at 9 KHz.
     
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