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PB103 Sine VCO

That's the sine wave VCO for the Paper-Bits. To adjust the wave shaper have a look at the manual at the bottom of the page.


Schematic



Paper-PCB

Parts

  • Resistors:
  • 1x 470 Ohm
  • 2x 1 kOhm
  • 6x 10 kOhm
  • 6x 47 kOhm
  • 3x 100 kOhm
  • 1x 9,1 kOhm
  • 1x 4,7 kOhm
  • Capacitors:
  • 2x 100 nF (foil)
  • 1x 10 nF (foil)
  • Diodes:
  • 1x 1N4148
  • Op-Amps :
  • LM 358
  • LM 324
  • Mechanical:
  • 1x 14 pin IC socket
  • 1x 8 pin IC socket
  • 1x Pin-Strip 1×15
  • 1x Right Angle Pin-Strip / Female-Socket Header 1×5
  • 1x Right Angle Pin-Strip 0,1 /Male 1×5
  • 3x jumpers
  • Potentiometers:
  • 2x 100k Trim Potentiometer
  • 1x 10k Trim Potentiometer
  • 1x 100k

Manual

Step 1 Connecting to power:
Once you've finished soldering all the parts into the PCB board plug it to power while touching the 2 chips. If any of the chips is getting hot unplug immediately and check the board for any mistakes (might be that the chip is inserted in the other way around).

Step 2 Checking the Oscillator:
Connect the saw-tooth, square output of the oscillator to the speakers by using a crocodile clip and check if its working.

Step 3 Using Oscilloscope:
Connect Probe 1 from the Oscilloscope to the saw-tooth pin (you should see already some square waves on you're oscilloscope). Next connect Probe 2 to connector Nr.4. Now you should see 2 different waves its time to shape the second wave into a beautiful sinus wave.

Step 4 Wave Shaping:
Connect the speakers to pin connector 4. (using that crocodile clip). Now start trimming the Potentiometer that is marked as 1 while checking the Oscilloscope and comparing the second wave with the first. Stop when you see or hear a perfect rounded sinus wave. Ok now we have our sinus wave but as you might notice the signal is too week, it's time to amplify it.

Step 5 Amplification:
Take the CV output to the speaker (watch out so that the jumpers are in the right position). DO the same in case of the Oscilloscope Probe. If you don't hear or see anything it means that the signal might have been lost, but no worries that's what we will do next.

Before you start trimming the other two trim potentiometers, it is important to know that you want to get you're wave as much amplified as possible without getting to a saturation level on you're op-amp. When that happens the sound will get distorted and you will see on you're Oscilloscope that you're wave is reaching a critical level. Another thing to know is that you're wave has a Pick to Pick range that is limited by the Op-Amps capacities and changing depending on the frequency. You want to get the best out of it (the highest voltage without reaching to over saturation) and that's when you have to check you're wave in all frequencies. In the lower ones for instance the waves amplitude is higher and thats the best situation for tuning you're wave and that is because here the wave will tend to get out of range (oversaturated) much more easier.

Now you can start trimming the 2 Trim Potentiometers. Poti marked as 2 controls the level of the wave. Poti marked as 3 controls the amplification of the wave. You will trim them simultaneously in the lowest audible frequency until you're wave will reach a similar pick to pick range as the saw-tooth wave. Once you're Sinus Wave is amplified you are ready to go, plug and play.


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