voltage amplifier??

Discussion in 'The Projects Forum' started by rand, Feb 15, 2009.

  1. rand

    Thread Starter Member

    Jan 13, 2009
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    I would like to know where how I could make a circuit to increase the voltage of my AC signal from a function generator... the generator itself doesn't really have its own amplifier (too low)...

    i have a 2N3055 NPN Transistor
    http://www.radioshack.com/product/index.jsp?productId=2062614
    and another pnp one from radioshack

    i guess i need a common base amplifier.., but i have no idea how to calculate resistors or capacitors if u need them?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    How much voltage does the function generator currently output, and through what frequency range?

    What kind of current output are you expecting?
     
  3. rand

    Thread Starter Member

    Jan 13, 2009
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    well if u measure voltage of the generator just by putting the leads to the generator its only a .2v - but thats nothing right? i directly hook it up to an led and its 2.1V
    i thnk the voltage is 3vp-p and the range of frequency is from 0-5mhz

    frequency is probably > 1 mhz depending on setup but im using about 1.68mhz right now

    basically i want to increase the distance the coils can be in our setup so the led still lights up... so a higher voltage should allow that?

    function generator-> coil with capacitor
    another coil gets energy from magnetic field of other coil - to capacitor + led
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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  5. rand

    Thread Starter Member

    Jan 13, 2009
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    yea i might try it again with only the second section of it without using the op-amp because it kinda just messed up... increased amps didn't help the distance?
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    The opamp increased the voltage swing and the transistors increased the current. the increased voltage and current results in increased power to the coil you are driving. But the opamp has a max frequency of 100kHz, not 5MHz.

    The coil is an inductor. It uses less current and less power as the frequency is increased. But it can be tuned to the frequency you are using then it will be much more powerful if the generator's amplifier can provide it with plenty of power.
     
  7. rand

    Thread Starter Member

    Jan 13, 2009
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    yea making the coil tuned to the frequency is kinda the problem then - i dont have an inductance meter - i have a multimeter and capacitors and resistors.. so i have no idea how to calculate the inductance of the coils
     
  8. rand

    Thread Starter Member

    Jan 13, 2009
    14
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    o so if the max frequency is 100 khz - i just have to tune the coil to 100khz somehow
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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