XR2206 Function Generator

Thread Starter

MCU88

Joined Mar 12, 2015
358
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?

 

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GopherT

Joined Nov 23, 2012
8,009
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.
 

Thread Starter

MCU88

Joined Mar 12, 2015
358
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?
 

Thread Starter

MCU88

Joined Mar 12, 2015
358
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
 

GopherT

Joined Nov 23, 2012
8,009
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,...
 

R!f@@

Joined Apr 2, 2009
9,918
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.
 

Thread Starter

MCU88

Joined Mar 12, 2015
358
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.
 

GopherT

Joined Nov 23, 2012
8,009
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.











image.jpg
 

Thread Starter

MCU88

Joined Mar 12, 2015
358
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.
 

Søren

Joined Sep 2, 2006
472
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.
 
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