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  #1  
Old 05-11-2009, 07:21 PM
dj_wizard dj_wizard is offline
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Default Op Amp used as a function generator

Hey guys i need ur help i have this square and tri function gen.
i did this circuit and it worked i only need to know the application of the resistance in it .. and also i changed the op amps to the lm741
can anyone help plz ?
thnx in advance

here is the circuit
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Old 05-11-2009, 07:28 PM
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Bill_Marsden Bill_Marsden is offline
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Check this thread out, see what you think...

http://forum.allaboutcircuits.com/sh...ad.php?t=12405
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Old 05-11-2009, 07:33 PM
dj_wizard dj_wizard is offline
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but i didn t use the pulse generator 555 ... now i know the 2nd op amp works as an integrator to the 1st o/p which is a square function .. but how does the first one works ?
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Old 05-11-2009, 07:41 PM
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Hello,

Take a look at this page of the eBook:
http://www.allaboutcircuits.com/vol_3/chpt_8/12.html
It is about positive feedback used with an opamp.

Greetings,
Bertus
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Old 05-11-2009, 07:47 PM
dj_wizard dj_wizard is offline
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thnx mate it was very helpful .. thnx both of u
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Old 05-11-2009, 11:13 PM
Audioguru Audioguru is offline
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The performance of a lousy old 741 opamp is bad above only 9kHz. Many better opamps cost the same, are single, dual and quad and perform well up to 100kHz.
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Old 05-12-2009, 01:48 AM
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Quote:
Originally Posted by Audioguru View Post
The performance of a lousy old 741 opamp is bad above only 9kHz. Many better opamps cost the same, are single, dual and quad and perform well up to 100kHz.
Perhaps you could prepare an update of National Semiconductor's Op Amp Circuits Collection (including the function generator of this topic, on page 9) using the modern chips. Then all the folk looking for circuits would no longer be offending you by using older style chips.
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Old 05-12-2009, 02:41 AM
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The lousy old 741 opamp should have been buried 20 years ago.
The very old LM107 opamp in the original circuit performs poorly above only 5kHz and was buried years ago.
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Old 05-12-2009, 02:57 AM
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Quote:
Originally Posted by Audioguru View Post
The lousy old 741 opamp should have been buried 20 years ago.
The very old LM107 opamp in the original circuit performs poorly above only 5kHz and was buried years ago.
So how about writing that upgrade? You could reduce the number of people learning on old chips! You could personally bury the old chips (metaphorically speaking).

Or you could post a circuit here with a more modern chip.

Or I suppose you could just keep whining.
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Old 05-12-2009, 05:33 AM
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Hello,

Here is almost the same schematic from the datasheet of the TLC272, a cmos opamp.



Greetings,
Bertus
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File Type: png Functiongenerator_tlc272.png (23.1 KB, 146 views)
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