Automatic characterization via power supply: got interesting results!

[T3sl4co1l]

Ah, you're moving into the general case of numerical analysis -- that is, to sample finite points of a (hopefully!) well-behaved function, and how to do it in a reasonable way, and also a stable way, while achieving some purpose (usually differentiation or integration).

You want good confidence that you aren't missing points, without taking a wasteful number of points in the process.   Too few points, or too naive a method, and you will find unlucky combinations spiraling out of control -- see Newton's method of root finding for a fairly simple case.

In this case, you're not so much after differentiation or integration, as just plotting the function at all.  But doing that is governed by the same arguments, so study of these subjects should be quite fruitful indeed.

Tim

[HendriXML]

My gut feel is that FETs will never satisfy you. They are all nanoFarads slow.
Try the BJTs, they are faster.

Haven't experimented on the time related stuff yet. I've got some interesting questions that need answers!

Will drive a Mosfet with the little circuit that I attached with the following testcases.
R1 -> 0 ohm
R1 -> 150 ohm; C1 not populated
R1 -> 150 ohm; C1 with up climbing capacity from 1nF to ?

I wish to know the lowest C1 which still makes a significant difference driving the Mosfet. Maybe my other circuit can react faster this way and compensate a bit for the gate capacitance.
Also it is nice to know if using 2 channels of the power supply in this way does any good. I'll be scoping the current via R2. The relay is the channel on/off relay of the power supply.

Most (scope settings as well) of it should be automated via SCPI, making testing a bit more fun.

[HendriXML]

In this case, you're not so much after differentiation or integration, as just plotting the function at all.  But doing that is governed by the same arguments, so study of these subjects should be quite fruitful indeed.

In my case only low hanging fruits! I'll leave the others hanging for those with excellent math skills!

[HendriXML]

Here're the results of the testcases

The yellow trace is the voltage across the mosfet.
The red trace is the voltage from the signal generator
The blue trace is the voltage at the gate

I had to use the signal generator to drive the gate because when the power supply channel switches on it seems that is first charges a big capacitor.
Then I tried another relay, but that showed bouncing.
So I used a signal generator, the scope and the signal generator are both at earths ground, so I had to use that as a ref at GND. Leaving no other choice to measure Vsd instead of the output voltage. But it should give about the same results (but inversed).

[HendriXML]

If I had to choose a capacitor I would probably take the 10nF one. It improves the response time, but also does not change the driving signal from the signal generator to much. The signal generator has a 50 ohms output, I've got to compare that to the op amp's one. But I think just trying out will be better.
During testing before these results I probably zapped the mosfet's gate. It was shown as very high oscillation, like it couldn't hold on to a certain resistance. But with a bit more Vsg it went up again, repeating this process.
Seeing this I know the mosfet in my other circuit got broke as well while making modifications, hence the strange noise.
https://www.eevblog.com/forum/projects/only-1x-gain-op-amp-regulated-power-supply-very-low-noise/msg2198082/#msg2198082

 I use an esd safe soldering station, mat, cutters, wrist band. But also have a wollen sweater  to keep warm at winter temperatures at our attic.

[n3mmr]

PSE? Explain, please!

Can we see your scripts, please?

[HendriXML]

I made a (Windows only) tool which can execute scripts written in a xml-based programming language of my own design.

Because it’s not documented I don’t think it is the best of choice. I myself find it however very useful for a lot of tasks. Follow my profile weblink to a GitHub location where a bunch of scripts can be found which do some advanced BOM reporting.

The scripts for controlling the power supply are far less complicated.

I think it’s worth asking what environment other people use.

[HendriXML]

I made a screenshot of part of the script to give an idea.

The class TSiglentSPD3303X is defined in another library which I also included an example of.

I included also the WaitForStabilizedVoltage function, because it sounds exiting, but only waits for the voltage to stop rising/dropping (Because of the endcap).