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Relaxation oscillator Noob need education

Discussion in 'General Electronics Discussion' started by Swedishguy, Jan 26, 2013.

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  1. Swedishguy

    Swedishguy

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    Jan 25, 2013
    Don´t laught please :) need some help about my project what i basically want is a solenoid "electromagnet" That switch its magnetic flux in a Oscillation fashion. Much like a speaker my solenoid is about 1.5 ohm. And to get the oscillation i research about relaxation oscillator and transistor oscillator but i went for the Rel for the of easy build. But i am very noob and i cant get it to work. The pic below show schematic and how i assemble it

    Probably i am so noob that my theory is not valid. I want to have the output voltage the same as i take in in order to get stronger or softer magnetic field but i only get 0.04 mv at the output i have an pot to regulate the freq the voltage do increase or decrease in the output some but do not oscillate i think.. i thing i destroyed the ic or i connected it wrong. or it is the wrong circuit all together? hope i have explained my self clear sorry otherwise!

    [​IMG]
    [​IMG]
     
  2. duke37

    duke37

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    Jan 9, 2011
    It looks as if you have a 1uF capacitor and a 20k resistor for the timing. Have you determined the frequency this will give you?

    If you connect the output to a load of 1.5ohm you will ask the op-amp to give out current many times what it is capable of. This may have killed it.
     
  3. Swedishguy

    Swedishguy

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    Jan 25, 2013
    Hello duke yea i have probably killed the IC my calculation with falstad simulation a 1uf cap and a 10k pot willbe around 45hz.. Yea i have seen i some circuit they usa a transistor at the end. But i have seen some use speakers to so i just tested..

    so what is best way to go about this?

    the cap in the pic is a 10uf just tested if the cap was dead
     
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Please explain what you want the solenoid to do. Restated, what are you building?

    Chris
     
  5. Swedishguy

    Swedishguy

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    Jan 25, 2013
    What i want simply a magnet to oscillation at a given freq and when i want to bump up the voltage the electromagnet becomes stronger pushing and pulling the magnet like an reverse speaker..

    [​IMG]

    sorry if i explaining bad i am trying my best

    best regards
     
    Last edited: Jan 26, 2013
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    I get what you want to do but I still don't know why. Is this an alternate energy project? I ask because we have a special section for that.

    Chris
     
  7. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    The solenoid needs a significant amount of current (hundreds of milliamps, or maybe amps) to produce significant magnetic flux density. If you want to drive it with a sinewave, you really need an audio amplifier, the type that's used to drive a loudspeaker. Then you feed your control sinewave into the Aux input of the amplifier and adjust the volume to get the amount of magnetic field variation you want.

    If possible, monitor the output of the amplifier with an oscilloscope to make sure it doesn't go into clipping, and keep an eye on the temperature of the amplifier's heatsink.
     
  8. Swedishguy

    Swedishguy

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    Jan 25, 2013
    it is not a energy project its not that big of an deal it is just an experiment im doing dont want to make signification magnetic flux, It work fine when i put 7 or 10 volts trough. the magnet goes forward and when i revers the poles the magnet goes back. now i just need it to do it faster.

    but i thank you all for trying i will continue to learn :)
     
  9. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Whether you drive the coil with a sine or square wave the magnet will appear to be motionless at 50 - 60Hz.

    Chris

    Edit: On second thought the term "stationary" is more apropos.
     
    Last edited: Jan 27, 2013
  10. Swedishguy

    Swedishguy

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    Jan 25, 2013
    explain why? a speaker is not motionless att 50 hz
     
    Last edited: Jan 27, 2013
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The motion will be too fast for your eye to track.

    Depending on the mass of the magnet, lighting, and the force applied to it may appear to have a ghostly transparent outline.

    edit: and that presumes it isn't stuck to the soft iron core.
     
  12. Swedishguy

    Swedishguy

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    Jan 25, 2013
    A speaker is not motionless at 50hz you see it move it ?
     
  13. Swedishguy

    Swedishguy

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    Jan 25, 2013
    Ethier case then i am wrong about the hz then it need to be slower.. that what i want to experiment with from 0 and up. And i have riged it so it don´t stuck to the iron core.
     
  14. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Your sketch indicates a pendulum of sorts so I'm assuming that you want to see the magnet swing back and forth. 50 - 60Hz is to fast for this. At these frequencies the visual effect will appear as a blurry magnet.

    Chris
     
  15. Swedishguy

    Swedishguy

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    Jan 25, 2013
    As i sayd Chris :) but i would like the circuit to do this to establish to experiment this
    to get the right Hz the higher the hz the shorter it oscillation and the lower it oscillate longer


     
  16. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    There's another issue that you have to deal with and it's not a minor one. The magnetic force required to push the magnet away from the coil (center equilibrium) will have to be much greater than to pull it toward the coil. You won't be able to suspend the magnet on a string either. Do you know why?

    Chris
     
  17. Swedishguy

    Swedishguy

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    Jan 25, 2013
    Well that would be a problem if it was on a string it is not, The mechanical is working the way i like i get my push and pull in my rig. The only thing i need. and would like answers to is to get my circuit to work.. so i can get my Hz the way i like. In my rig if i put volt between 3-12 dc it pushes the magnet forward then when i turn of the voltage the magnet will go back to its original position because the magnet attract to the iron core. but there is at distance from the magnet and the iron core so when i turn back the voltage the magnet goes forward.

    so my original question is the circuit.
    thanks
     
  18. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    We get quite a few topics like this. When I say "like this" I'm referring to topics where the OP is withholding information. We are not novices here. We know it when we see it.

    Second guess... reciprocal engine also called a magnetic piston engine or solenoid engine?

    Chris
     
  19. Swedishguy

    Swedishguy

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    Jan 25, 2013
    Im sorry that you think i am withholding information. That is not my intention i am trying to explain the best to my knowledge. And i don´t think you are novices that´s why i am here to begin with to get the word from people that are experience in electronic

    and i am a novice and i can´t even begin to say what it can be called. but yea you could call it a solenoid engine but more a electromagnet engine ? solenoid with a iron core is defined like a electromagnet right?
     
  20. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    FYI, these types of motors are a favorite of model maker machinists. You can watch Youtube for hours and never run out of beautiful examples. Even Tublcain made one. None of them reverse polarity the way you're attempting to do it because it's not practical. The timing is accomplished by a set of points.

    Chris
     
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