Hi,
The problem comes from the open collector output: the high level is created passively, with the 10K pull-up.
The current in this resistor is insufficient to overcome the capacitive parasitics and the stored charge of the transistor. You have to use a resistor as low as practical, and add a totem-pole buffer to remove the effects of loading.
But in my opinion, it is rather silly to use a full-blown function generator just to generate square waves.
If you want clean, frequency-variable square waves, you can use a schmitt trigger oscillator (CD40106) followed by a flip-flop to get a symetrical waveform (CD4013) and an output buffer made 8 bus drivers paralleled (74C244). This is just an example, there are many others options that are simpler, cleaner and cheaper than the 2206.
LV
The problem comes from the open collector output: the high level is created passively, with the 10K pull-up.
The current in this resistor is insufficient to overcome the capacitive parasitics and the stored charge of the transistor. You have to use a resistor as low as practical, and add a totem-pole buffer to remove the effects of loading.
But in my opinion, it is rather silly to use a full-blown function generator just to generate square waves.
If you want clean, frequency-variable square waves, you can use a schmitt trigger oscillator (CD40106) followed by a flip-flop to get a symetrical waveform (CD4013) and an output buffer made 8 bus drivers paralleled (74C244). This is just an example, there are many others options that are simpler, cleaner and cheaper than the 2206.
LV
Make an oscillator like this one:
http://www.interq.or.jp/japan/se-inoue/e_ckt13.htm
eventually followed by a 4013 in divide by 2 mode if you need a perfect symetry, followed by some kind of buffer (you can use the five remaining 40106 or a supplementary IC).
Alternatively, you can use a ready made oscillator like the 4046 or 4047; with the latter you have the advantage of having the flip-flop already included.
Try to find information by yourself, it's so elementary and there are huge amounts of info on the web.
http://www.interq.or.jp/japan/se-inoue/e_ckt13.htm
eventually followed by a 4013 in divide by 2 mode if you need a perfect symetry, followed by some kind of buffer (you can use the five remaining 40106 or a supplementary IC).
Alternatively, you can use a ready made oscillator like the 4046 or 4047; with the latter you have the advantage of having the flip-flop already included.
Try to find information by yourself, it's so elementary and there are huge amounts of info on the web.
old thread but i am back to this cause now i need it again ...
fixed the square wave issue adopting the output scheme of this circuit http://electronics-diy.com/electronic_schematic.php?id=818
then the problems are
1) i get spikes on both up or low sine ( will post pics tomorrow)
2)also it is impossible to adjust the lower wave form correctly , the lower part of the sine is out of center
any ideas ?
fixed the square wave issue adopting the output scheme of this circuit http://electronics-diy.com/electronic_schematic.php?id=818
then the problems are
1) i get spikes on both up or low sine ( will post pics tomorrow)
2)also it is impossible to adjust the lower wave form correctly , the lower part of the sine is out of center
any ideas ?
Hi Sakis
That glitch is inherent in in all simple 2206 sinewaves.
Elektor Function Generator generator from ~1980 had the same issues, even as a complete and well built instrument.
The problem is with switch and lead capacitance at pin 13 and the solution they used in a revised circuit, was to fit a very closely wired BS170 mosfet switching device. I hope you will know how to wire that up, because I can't recall all the details of what voltage was used.
EDIT: This might help: http://www.granta.g4axx.com/pdfs/Generator.pdf
Good luck and
That glitch is inherent in in all simple 2206 sinewaves.
Elektor Function Generator generator from ~1980 had the same issues, even as a complete and well built instrument.
The problem is with switch and lead capacitance at pin 13 and the solution they used in a revised circuit, was to fit a very closely wired BS170 mosfet switching device. I hope you will know how to wire that up, because I can't recall all the details of what voltage was used.
EDIT: This might help: http://www.granta.g4axx.com/pdfs/Generator.pdf
Good luck and
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Here you go, seeing that this is for visual aspects of audio, a video of an XR2206 generator should be just right. We expect you to at least match this one...
DIY XR2206 Function generator - YouTube
DIY XR2206 Function generator - YouTube
This might be a very wrong answer.. someone else will have to confirm, or if you have the parts it wouldn't be hard to try.
A schmitt trigger on the output might give you 'sharper' output. A high-speed opamp in a buffer config will give a low impedance output.
I would recommend the 555 timer-based oscillator that bobodioulasso posted. Simple and effective.
Hengy
A schmitt trigger on the output might give you 'sharper' output. A high-speed opamp in a buffer config will give a low impedance output.
I would recommend the 555 timer-based oscillator that bobodioulasso posted. Simple and effective.
Hengy
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