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We have a project to make a function generator that outputs a square, triangle, and sine wave. We have already made one, but there are several problem with it.

  • The square output only has the positive side (Vmin = 0 V; Vmax = 11.8 V). Maybe an offset circuit can fix it? enter image description here

  • The amplitude of the triangle and sine waves can be varied, but this doesn’t work with the square wave. We’re thinking that an amplifier circuit can solve this problem.

Here's our schematic:

enter image description here (Copied from ElecCircuit)

UPDATE: The square wave output is now fixed. We just now need to put the three waves through an amplifier circuit, so it can amplify its amplitude and vary it with a potentiometer as well. Any recommendations for an amplifier circuit?

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    \$\begingroup\$ We're going to need a lot more information on your circuit to be able to tell why it's not working. \$\endgroup\$
    – Hearth
    Commented Jan 28 at 0:23
  • \$\begingroup\$ "The square wave output is now fixed." Have you fixed the problem of "The amplitude of triangle and sine wave can be varied but it doesn’t work with the square"? \$\endgroup\$
    – Math Keeps Me Busy
    Commented Jan 28 at 6:35
  • \$\begingroup\$ for that, we're thinking we can just make an output wave pass through an amplifier circuit since we also need to have a higher amplitude for the sine and triangle waves. Then with that circuit also, we can have control the amplitude for it. \$\endgroup\$
    – Beans Carlo
    Commented Jan 28 at 6:41

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Pass it through a capacitor in series (in effect, pass it through a high-pass filter). That will remove the DC component. On the far side of the capacitor, the mean voltage will be 0 V.

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  • \$\begingroup\$ hi, sorry for asking. I added our schematic diagram as well as the result of our square wave. Does your answer still solve our problem? \$\endgroup\$
    – Beans Carlo
    Commented Jan 28 at 1:30
  • \$\begingroup\$ It solves one of your problems. Since you don't have a negative power supply you can't generate negative voltages directly. But AC coupling the SQUARE output to a resistor to ground will center the square wave around zero. Make that resistor a potentiometer and taking your output from the wiper gives you volume control, solving your other problem. The output impedance is poor (depends on pot location) but if you're feeding a high impedance load it can work. Choose C and R large enough to pass lowest frequency of interest. \$\endgroup\$
    – td127
    Commented Jan 28 at 1:58
  • \$\begingroup\$ thanks for the answer, it solved our problem. Now, we need to amplify our outputs( sine, triangle, square wave). We are thinking of putting our outputs through an amplifier circuit so that the amplitude can be much higher and so that we can vary it also. Do you happen to know an amplifier circuit that we can use? \$\endgroup\$
    – Beans Carlo
    Commented Jan 28 at 6:02
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    \$\begingroup\$ That's a separate question. You should accept this answer and post a new one. \$\endgroup\$
    – td127
    Commented Feb 2 at 18:36

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