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Need help with Op amp buffer

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hummusdude:
I'm trying to build a circuit that will buffer the output of an AD 9850 waveform generator module. The 9850 is very sensitive to even the slightest esd and frequently shuts off requiring a reboot of the waveform generator. I built the circuit in the attached schematic but it's not doing what I'd hoped. The rail splitter seems to work pretty well although the + and - values are not exactly even distance from virtual ground. R6 is 1M because I don't want to amplify the signal...just buffer it.

The datasheet for the LM741 says it will work without a negative ref voltage so I hooked it up with V- at 0V but the output would not go below 2V with 0V in. So I built the rail splitter hoping that a negative voltage for V- might do the trick. I imagine I'm getting some chuckles at this point. Obviously, I don't understand op amps well enough to figure this one out so hoping for some advice on how to buffer the AD 9850.

Zero999:
The rail splitter looks fine.

The schematic isn't clear. Where exactly do you have the input and output leads connected to the circuit?

It could be a grounding problem, the output of the rail splitter must be the point from where all voltages are measured from. The 0V of both the input and output should be connected to the output of the rail splitter.

By the way, the LM741 doesn't have sufficient slew rate or bandwidth to make full use of the AD9850.

mikerj:

--- Quote from: hummusdude on December 21, 2019, 05:31:56 am ---The datasheet for the LM741 says it will work without a negative ref voltage so I hooked it up with V- at 0V but the output would not go below 2V with 0V in.

--- End quote ---

The ancient 741 does not have rail-rail input common mode range or output swing, typically it can only get within about 2v of the rails.

avogadro:
It looks like you connected the diode pair to the GNDREF. Try removing that connection. I attached the schematic.

unitedatoms:
That's interesting splitter. Nice answer, @Avogadro

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