You can not tell any of this from your experiments. You need the schematic and the exact compensation scheme. The 5534 has this problem but only at > 10's of kHz.
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Scott,
The chip is obsolete. I got a bunch for six peanuts. I now have four amplifiers that with a gain of 20 that are more than 26 dB quieter than my AP.
The maximum input level is .05 V RMS. To match my new to me HP 54542A scope I will have to add a second stage.
These work just fine and BTY power consumption per card is under 2 watts.
What I found interesting also is how cheap the other surface mounted components were. The PC card was the most expensive item followed by the batteries.
That's all fine, don't say supercapacitor's on the rails reduces noise of anything but YOUR circuit.
The issue may be that PSRR is only one way to address noise. The other is with a device with variable conductance/resistance fed from a matching resistor and a zero ohm power source.
But my issue was why did adding capacitance cause a change in the 1/F inflection point. I suspect I have a clue as to why.
(Is there anything we can agree on? Perhaps the sky is blue?)
I'm not sure we have gotten to the point of there being something to agree or disagree on i.e. "The other is with a device with variable conductance/resistance fed from a matching resistor and a zero ohm power source" makes no sense in this context.
Is this a result of calculation or of measurement? If you’ve measured the noise, how did you do it? And what instrument did you use to measure that low?
George
Mr Simon,
please pose that to (genuine) men only.
(fair chance that asking a woman what color the sky is, after endless debate, eventually leads to a response that it is not a simple question to answer. Been there, done that, never ever a 2nd time)
I use a 60 ohm resistor as a 1 nV/rtHz reference. 6 ohms as 316 PV.
With four amplifiers I can use autocorrelation and differential inputs.
But for something's low noise is just faster.
It really is a case of I can build it, so why not.
I noted Scott didn't agree the sky is blue...
On your gain of 20, to not effect 100pV or so noise how is this achieved? A 4.75 Ohm and .25 Ohm feedback network (just making up a case)? Now you have the issue with a poorly chosen battery that you actually have more gain to the rail than to the output. I wish you would show us exactly what you are doing rather than what you think you are doing.
BTW IMO the difference between a battery and super-capacitor in this context is almost semantic.
300/15 for each amp. So just a bit less resistor noise than rated noise.
The super cap can be connected closer to the load so less path resistance and noise.
10 cm of #18 is .002 Ohms these things are not your problem. Unless you really tried the resistance of the wire can not matter. The cap goes on the supply not the load so I assume you are putting 24 on each rail right at the parts?
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Off topic, but interesting photos - the-magnets-of-the-large-hadron-collider
A ton of interesting links at the bottom of the page too.
Dan.
A ton of interesting links at the bottom of the page too.
Dan.
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Wow we can't even agree on the resistance of wire or even the length required too hook up the D cell sized batteries.
BTY my test clip leads run about .12 ohms each.
Clip leads, just the way NIST would do it. That resistance number came from the standard AWG table, .0210 Ohms/meter for #18 copper. If you were serious on doing serious research into a problem you would make a deliberate attempt to eliminate the confounders. In this case it is trivial, use #2 battery cables you can get them at any auto parts store.
BTW my version of the Jung/et al super regulator has +-15V at an ESR of 10-5 Ohms DC to 1kHz (measured with a 4 point Kelvin connection).
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