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Topic: Ne5534 OPAMP amplifier (Read 3091 times) previous topic - next topic

MarkT

You need a rail-to-rail opamp, and use the right configuration to amplify the signal without loading it, the
circuit you described has a variable input impedance dependent on the input potentiometer so its not
going to useful for measurement.  With 200 ohm burden you should keep the loading impedance well above
that, so 20k or more is good, or else you'll have to compensate for the loading in your calculations - which
requires that impedance to be constant/known, not a potentiometer...

You existing circuit assumes the opamp can operate down to 1/3rd of 5V, 1.7V or so, and the NE5534A
just cannot do that - it can barely get down to 3V, which is why its minimum supply range is 6V.  In practice
this chip is used with +/-15V or +/-9V supply in low-noise audio amps and effects units, its not a low-voltage
device, its a low noise device.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

polymorph

Yes but he is not using +-5V, just a single ended 5V so that corresponds to +-2.5V. So he is trying to operate it out of spec.
Yes, someone mentioned adding a -5V supply, I was pointing out that even with that, it isn't the best idea.

Quote
That bit I posted was from the Ti data sheet.
OK. I specified On Semi and said others may vary.
Steve Greenfield AE7HD
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