Homebrew Function Generator

Discussion in 'The Completed Projects Collection' started by kyle7119, Oct 14, 2014.

  1. kyle7119

    Thread Starter Member

    Feb 11, 2011
    71
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    [​IMG]
    [​IMG]

    Frequency Counter

    The square wave is fed into a digital input on an ATMega328 microcontroller. The digital input is triggered every time the square wave rises above the logic high threshold. The microcontroller samples the pin at a high rate and counts the number of cycles per second. This number is sent to the display via the MAX7221 display driver.

    http://forum.allaboutcircuits.com/attachments/frequency-counter-png.74142/

    Power Supply

    The step down isolation transformer is fed through a bridge rectifier. The center tap is tied to ground to provide both a positive and negative supply. The rectified voltage is regulated to a ±12 V line and a +5V line (for the digital logic ICs).

    http://forum.allaboutcircuits.com/attachments/power-supply-png.74141/

    XR2206 and Amplifier

    The XR2206 is configured according to the recommended circuit on the datasheet. The output is selected via a 3x3 rotary switch. This toggles the output feed, the symmetry adjustment, and the amplitude fine adjust, allowing these variables to be configured independently for each waveform. The XR2206 output is fed through a buffer amplifier and then a potentiometer to control amplitude. After this, the wave is summed with a DC voltage to adjust the DC offset. The AD811 amplifier drives the final output stage.

    http://forum.allaboutcircuits.com/attachments/xr2206-png.74140/

    [​IMG]
     
    darrough likes this.
  2. Wendy

    Moderator

    Mar 24, 2008
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    If you want I could send you a bunch of decals from my label maker. Modern label makers leave the old ugly Dyno labellers in the dust, and look quite good. PM me if interested.

    Nice work, very professional looking.
     
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Looks good outside, will certainly look better with labels.

    Any inside pics?

    You have a sync output socket (good idea), but I can't find it on the schematic?
     
    DerStrom8 likes this.
  4. kyle7119

    Thread Starter Member

    Feb 11, 2011
    71
    17
    This was actually a school project and I ended up cannibalizing parts after the project was turned in. I just used protobard with socketed chips and some static free foam to insulate it from the case. Kinda a hack-job.

    I tried adding the sync but never got it working in time. The output was there as a place-holder just in case.
     
  5. kyle7119

    Thread Starter Member

    Feb 11, 2011
    71
    17
    Alright, I attached the code to the original post.
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    panic mode likes this.
  7. Wendy

    Moderator

    Mar 24, 2008
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    Price is always an object though. Like I said, my labeler is 20 years old. Every couple of years I change the batteries out, and that's it.
     
  8. MrChips

    Moderator

    Oct 2, 2009
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    Seven-segment LEDs will look better behind a bezel and colored filter.
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    I like the display though, it is very cool!

    I may rob the freq counter for some of my projects sometime.
     
  10. kyle7119

    Thread Starter Member

    Feb 11, 2011
    71
    17
    Yeah, price was the driving factor in this. I found these cases on Jameco for $8-10 each. Best deal on cases I could find. A drill and nibblers is all you need to make the panel.
     
  11. kyle7119

    Thread Starter Member

    Feb 11, 2011
    71
    17
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