So i was asked to design a function generator that eventually produces a sine wave at the output of the circuit and this is what i have come up with so far. A Schmitt trigger and then an integrator and the triangular wave to sine wave converter. But at the moment, i have done a lot of research to understand whats going on completely, and i sort of understand.I'm just very unsure what to do next?

i want to produce a square wave and a triangular wave that give me 5v as well as symmetrical. I should also be able to vary the frequency from 0.5kHz to 10 Khz i also must use an LM741 op amp and 1N4148 diode

i tried calculating R1 and R2 but i did not get the output i wanted so they are probably incorrect.

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and this is what i got. Also i know i should use diode to reduce the voltage but im not sure where i should place them

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  • \$\begingroup\$ This smells like a homework question. Care to elaborate how did you "come up so far" with this circuit? \$\endgroup\$ Apr 7, 2019 at 17:04
  • \$\begingroup\$ its mostly a lab question, but i came up with this while reading through the textbook and research.. \$\endgroup\$
    – HaidyE
    Apr 7, 2019 at 17:10
  • \$\begingroup\$ You are on the right track. You have forgotten to put a resistor between V4 and D1. \$\endgroup\$
    – EinarA
    Apr 8, 2019 at 2:18

1 Answer 1


Many function generators are designed with specs similar to yours:

  • variable frequency

  • amplitude of output independent of frequency

  • square, triangle, sine selectable.

An often-used block diagram starts with a triangle-wave oscillator. If an op-amp is used for this oscillator, it could be a Schmitt type integrator. Output is frequency-independent amplitude that satisfies the triangle output requirement. Frequency can be varied by feeding the integrator with variable current source.

Square wave output is easily derived from the triangle wave with a comparator chip. Again, comparator output amplitude is independent of frequency. While an op-amp makes an inferior comparator, it is possible.

Sine output is derived from the triangle wave, with a network of diodes/resistors to approximate a linear piece-wise sinusoidal wave. This method also yields a constant amplitude independent of frequency. An op-amp could be used as a summing amplifier that adds together currents from the diode-resistor network.

A modern approach used an arbitrary waveform generator (all digital) to generate just about any wave shape you desire. A digital-to-analog converter is the last stage of this process: again, it supplies output whose amplitude is independent of frequency.
A square wave clock source increments through multiple steps of one cycle. A small counter generates addresses to a RAM or ROM where numerical (signed binary?) discrete waveform samples are selected - these feed an analog-to-digital converter. However, these stages are digital and don't meet your op-amp requirement.


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