Signal Converter

Discussion in 'Homework Help' started by BXL, Nov 19, 2013.

  1. BXL

    Thread Starter New Member

    Nov 19, 2013
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    I have to do a signal converter circuit for coursework.
    This circuit should transform an sine wave input in a square wave, sawtooth wave and in triangular wave with same frequency, amplitude and Dc offset from the input

    The sine wave input could has amplitude varing from o to 2, and it could have a +/- 5 DC offset.

    To build this circuit I can use just Opamps, Transistors(Mosfet), and diodes.

    In thought passing my input wave in a half-wave rectifier circuit and then pass it output in low-pass filter to get it offset. it works fine, for a 2V amplitude wave, but it fails for other amplitudes.

    To transform the wave i use a high-pass filter to get the sine ana make it pass for a comparator, then i use a sommator and a inverter.It works ok for an 2V amplitude input.
    To the triangular output I'm doing something similar( after the input I pass it throught a OpAmp integrator.

    I haven`t tried the sawtoooth yet.
    Hope someone can help me
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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  3. BXL

    Thread Starter New Member

    Nov 19, 2013
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    I checked this circuit, but it doesn't work for me.
    I uses BJT transistor. As I said I can just use MOSFETs
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    Most (not all) circuits that use BJT can be converted to an equivalent FET-based circuit fairly easily, and vice-versa.
     
  5. BXL

    Thread Starter New Member

    Nov 19, 2013
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    I`ll see it later. Anyone know hoe can I fix the amplitude trouble I get when I change the input amplitude?
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Use a precision rectifier to get the offset value. That puts the diode inside the feedback loop which eliminates the forward drop from the diode in the output value.
     
  7. BXL

    Thread Starter New Member

    Nov 19, 2013
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    Anyone know how can I make the output wave has the same amplitude than the input sine wave?
     
    Last edited: Nov 20, 2013
  8. BXL

    Thread Starter New Member

    Nov 19, 2013
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    I already made the square and the tringular.Anyone know how can I get a sawtooth wave from a sine or aquare wave? I can just use Mosfet and OpAmps, capacitors, basically analogic components.
     
    Last edited: Nov 22, 2013
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    You could use an opamp to make a constant-current source, use that to charge a cap, detect when the cap voltage reaches the sine (or square) peak amplitude, then discharge the cap rapidly.
     
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