Hello...

Has anyone here done a function generator project using the XR2206 chip? I did one a while back and I found it to be a toy.

Has anyone got a better alternative to provide sine, square and triangle with the addition of variable duty cycle? Something using OPAMPs perhaps?

 

Would love to have a quality function generator.

 

Hello...

Has anyone here done a function generator project using the XR2206 chip? I did one a while back and I found it to be a toy.

Has anyone got a better alternative to provide sine, square and triangle with the addition of variable duty cycle? Something using OPAMPs perhaps?

Maybe you could actually tell us what you want and/or need that the xr2206 doesn't provide.

 

Would love to have a quality function generator.

You'll be getting one. The XR2206 is not the solution though. The output is not true AC and cannot directly drive loads. It has no square wave. It has no variable duty cycle. The distortion is high. Very disappointed.

Ground up OPAMP design? Schema suggestions anyone?

 

Maybe you could actually tell us what you want and/or need that the xr2206 doesn't provide.

• Variable Frequency 0.1Hz to 1MHz
• Sine, Square and Triangle waves
• Variable Duty Cycle
• Variable Amplitude
• Ramp Function
• True AC or Pulsating DC Output (feature with toggle switch)
• Digital Display For Frequency

 

You'll be getting one. The XR2206 is not the solution though. The output is not true AC and cannot directly drive loads. It has no triangle wave. It has no variable duty cycle. The distortion is high. Very disappointed.

Ground up OPAMP design? Schema suggestions anyone?

I've never seen a function generator drive a load.

Also, the xr2206 can output a triangle wave to sawtooth wave, the designer of the power supply you showed just didn't bother to give you those functions on the control panel. It can also do FSK modulation. Distortion can be controlled with two pins - not perfectly, but,...

 

I got no ideas and I am still looking for something that can be easily built and provide pure clean sine wave in the audio range
And may be square wave to test circuit as such.
Variable sine wave function.
Able to drive low Z loads
Variable amplitude as such.

All the things needed to test circuits from Audio to Digital.

 

I've never seen a function generator drive a load.

Also, the xr2206 can output a triangle wave to sawtooth wave, the designer of the power supply you showed just didn't bother to give you those functions on the control panel. It can also do FSK modulation. Distortion can be controlled with two pins - not perfectly, but,...

Square wave sorry. See post #5 too.

 

Hello,

Have a look at some of the links from this page of the EDUCYPEDIA for oscillator circuits:
http://educypedia.karadimov.info/electronics/circuitsoscillator.htm

Bertus

 

Square wave sorry. See post #5 too.

Here is the perfect chip. It meets everything you asked for and It can also do 0.01 Hz instead of 0.1 Hz that you asked for.
Sine, square and triangle (that can be distorted to various ramp signals). 1 to 99% duty cycle.

 

Here is the perfect chip. It meets everything you asked for and It can also do 0.01 Hz instead of 0.1 Hz that you asked for.
Sine, square and triangle (that can be distorted to various ramp signals). 1 to 99% duty cycle.

The square wave output uses a separate pin. It is a dog of a chip.

 

Hello,

Have a look at some of the links from this page of the EDUCYPEDIA for oscillator circuits:
http://educypedia.karadimov.info/electronics/circuitsoscillator.htm

Bertus

The ICL8038 looks good. Very cheap too.

 

The ICL8038 looks good. Very cheap too.

Unfortunately, the 8038 only goes to about 100 KHz for the sine and triangle. A MAX038 is a closer fit to what the TS wants. See the thread by Adam555:
http://forum.allaboutcircuits.com/threads/max038-function-generator-design.102905/
Warning... quite long.

 

If you can get it, the MAX038 (upgrade of ICL8038) goes to 20MHz or 30MHz and was/is pretty expensive IIRC.
Both are seriously obsolete, but may be found at hobby electronics shops on-/offline (perhaps eBay?).

For new designs, use Direct Digital Synthesis (DDS) instead, whether the old-skool-way or with one of the dedicated chips that's become available. You're not stuck with sine, triangle and square with DDS - any waveform you can imagine (in the bits available in a particular design) can be made.

Whichever way you shake your electrons around, you should plan on incorporating both 50 Ohm and 600 Ohm output impedance buffers, if you want to be able to calculate anything from your measurements.

 

I suspect that the reason analog waveform generators like the MAX038 and the Exxar chips are going extinct is because the same functionality can be had my digital means. Once it is digital, it is easy to set the frequency precisely and you don't have to pass signals through potentiometers.

The Analog Devices AD9850 is one such chip.

www.analog.com/en/products/rf-microwave/direct-digital.../ad9850.html

 

Hello Dick,

Your link does not work.
I assume you where linking here:
http://www.analog.com/en/products/rf-microwave/direct-digital-synthesis-modulators/ad9850.html

Bertus

 

Thank you, Bertus.