How to build a function generator

In summary, you would need a 555 timer, a potentiometer, and an opamp to create a square wave generator.
  • #1
V0ODO0CH1LD
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I have to deliver a project for my analog electronics course and I wanted to build a synthesizer (the simplest version possible since I am a total beginner at this). It would basically be a function generator with a knob used to control the frequency (with maybe banana plugs for sound output). How would I go about building this function generator from basic components like capacitors, resistors and diodes?

I read that a triangular wave can be generated by repeatedly charging and discharging a capacitor from a constant current source. How would the simplest version of this work? I have to actually build the project and I don't even know where to start.
 
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  • #3
I guess the starting point is to build a function generator that generates only triangular waves. Can you point out any resources of tutorials on that?? Something that explains the function of each component on the circuit and all that!

Thanks!
 
  • #4
  • #5
note: disregard the resistor and cap values, you'll have to choose those to suit your needs.
 
  • #6
get the data sheet for the MAX038, maxim doesn't sell the chip anymore but if you look around you should be able to find it.
 
  • #7
Hint: The integral of a square wave is a triangle wave and the integral of a triangle wave is very close to a sine wave. Biggest problem - amplitude varies with frequency so you would need automatic gain control.
 
  • #8
The simplest way to do this is using a 555 timer. The timer signal itself is a sawtooth which is the typical waveform used most often in analog music synthesizers. If you need sine your can filter it.
 
  • #9
Okay! Thanks for all the replies! After doing some research I've decided to construct the simple square wave generator shown in this link:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/square.html#c2

I wanted to know what are the components I should buy if I wanted to build it so that it ranges over the audible frequency (20Hz - 20kHz). Could I just put a potentiometer where R is in that figure? What are the actual values of the components I should buy?
 
  • #10
That will work but keep in mind it will probably be easier to make a 555-based square wave generator work than if you do it with an opamp.

That said, most standard Rs and Cs will work fine in audio frequencies. You can use a potentiometer for R but it is best to use the pot for only part of the R.

As for the values, you calculate what you need from the circuit description you linked to. All you have to do is pick Lambda and the period you want then everything else can be calculated. Be sure the common-mode range of the op amp you use is good enough to handle whatever value of lambda you choose.

Have fun!
 

Related to How to build a function generator

1. What is a function generator and what is it used for?

A function generator is an electronic device that is used to generate a variety of electrical waveforms. It is commonly used in electronic testing and circuit analysis to simulate different signal waveforms such as sine, square, triangle, and sawtooth waves.

2. What are the components needed to build a function generator?

The basic components needed to build a function generator include a voltage-controlled oscillator (VCO), a waveform shaping circuit, a frequency control circuit, and an output buffer amplifier. Additional components may include a power supply, control knobs, and a display screen.

3. How do I choose the frequency range for my function generator?

The frequency range of a function generator is determined by the VCO and frequency control circuit. To choose the desired frequency range, you can adjust the values of the resistors and capacitors used in these circuits. Alternatively, you can use a function generator kit that comes with pre-calibrated frequency ranges.

4. Can I add extra features to my function generator?

Yes, you can add extra features to your function generator such as amplitude modulation, frequency sweep, and frequency offset. These features can be achieved by adding additional circuitry and components to the basic function generator design.

5. What are the safety precautions to keep in mind while building a function generator?

It is important to follow standard safety precautions while building a function generator. This includes using appropriate tools and equipment, wearing protective gear, and ensuring proper grounding to prevent electric shocks. It is also recommended to have a basic understanding of electronic circuits and to double-check all connections before powering on the device.

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