Something I noticed after making my first Joule Thief today in relation to the radio

Discussion in 'Wireless & RF Design' started by Rolland B. Heiss, May 6, 2015.

  1. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    After finally making a working Joule Thief today I set the unit on the dresser by my bed to test as a night light and the radio happened to be on. I didn't give it a second thought but when I touched the connection leads from the Joule Thief to the 1.5 volt battery it made static on the radio. So I got curious about this and tried a simple Morse code by touching quick for dot and a bit longer for dash and here I was sending code to my radio in the form of static. Why does this work and how? Is it the 2N3904 which is sending the signal?
     
  2. Ramussons

    Active Member

    May 3, 2013
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    The Joule Thief uses the 2N3904 as a High Frequency oscillator whose harmonics are picked up by the radio nearby.
     
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  3. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    Thanks for the explanation Ramussons!
     
  4. Art

    Distinguished Member

    Sep 10, 2007
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    You could oscillate the switching device a the correct frequency for the station,
    amplitude modulate it with your voice using another transistor,
    and BAM! Radio Rolland :)
     
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  5. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    I'm really starting to have some serious fun with everything I'm learning and everything people such as yourself are teaching me Art! :)
     
  6. Ramussons

    Active Member

    May 3, 2013
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    Radio Rolland on the following Frequencies :rolleyes:

    F, 2F, 3F, 4F, ......... :D
     
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  7. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    I'll definitely look into this in depth as time permits Ramussons! One interesting thing I discovered today after having to re-solder and re-solder a certain LED with a very short lead that finally broke off after breaking off a couple of times before which I had pulled from a garden light as old as Adam and Eve no doubt it caused me to rip another LED from a newer component to use instead. At any rate, once I got the better LED affixed I went to set the unit next to my bed as the radio which plugs into my wall outlet was playing. I usually have the radio going 24/7 for some reason. But I noticed that when I put the fixed Joule Thief near the radio it worked like a volume knob and the sound diminished. So I placed the Thief right up against the radio (seems to only work this way with AM broadcasts) and it made the station go completely silent. Therefore I am intrigued in many ways this evening as to potential applications for a circuit I merely meant to use as off grid lighting or for power outages. Somehow it cancels out the strong signal from my plugged in radio and I'm trying to figure out why.
     
  8. Art

    Distinguished Member

    Sep 10, 2007
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    The signal from the station isn't as strong where it comes in the antenna. The same thing wouldn't happen as you moved the whole setup closer to the radio station.
    If this is all interesting, you might benefit from your lowest level amateur radio course, which in my country can be done in a week.
     
  9. Art

    Distinguished Member

    Sep 10, 2007
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    I'm suprised (and glad) AM radio is still a thing :D

    You could think of AM radio... Your voice or music vibrating the strength of a frequency.
    The frequency your radio is tuned to.
    So any interference on that frequency is not desired.

    FM radio.. You could think of the frequency your radio is tuned to only a centre frequency... Your voice or music vibrating the tuning dial (if you are operating the transmitter) where the tuning dial is always spring loaded to return to the centre frequency.
     
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