Programmable DC Electronic Load

[Easy peasy]

1 k seems a bit high for a source resistor ....

--- Updated Sep 12, 2021 ---

a lot of 100pF caps everywhere ..... possibly a bit small for the 20V psu smoothing ...

 

[KlausST]

Hi,

It's about half a year from thread start.
I guess if the OP showed the schematic earlier .. it could run for months now.

Klaus

 

[HighTechPower]

Hi. As references I used previous design of a YouTuber Skullmanhobbyelectronics and some application notes in drawing schematics. I'm waiting for someone to post his evaluations. As I said I'm leaving business activities but it would only be a long break so that I can learn math A to Z. Any help in finding a PhD math expert at concessional rates would be highly appreciated. It would make my approach multidimensional. My experiences says be expert first, then expert generalist, and then be expert again. I never stopped learning & practicing. I'm at age 49. There are many engineers who may never used math in designs but my approach is different being physicist by education. You can also view my previous closed accounts posts as ElectroPhysics here as a fun.
Regards

 

[D.A.(Tony)Stewart]

1 k seems a bit high for a source resistor ....

--- Updated Sep 12, 2021 ---

a lot of 100pF caps everywhere ..... possibly a bit small for the 20V psu smoothing ...

Looking at the layout for large e-caps, the schematic simply does not have the final value selected and all the same values for passives. Mu did a decent job in designing this board and seems to be aware of the standard practice of spreading C values in order to spread the lowest ESR bandwidth possible while using the low parasitic inductance of a square geometry. (based on log( l/w) ratio)

--- Updated Sep 22, 2021 ---

If you want to learn from other autodidactic experts in math/physics applied to electronics then scan all the answers of @jonk.

I only took 4 years of physics in the early '70's in EE, enough to understand some fundamental behaviours but never smart enough to use it at a research level. My expertise was from learning it the hard way and then being able to convert higher order nonlinear behaviours into 1st or 2nd order linear characteristics, which is not the rigorous math approach of physics, just the application of it.

From the simplest part the PN diode there are about 6 levels of behaviours, but if you observe the thermodynamic properties of NTC and PTC you can be successful in using level 1 math. Vf=Vth+If+Rs for any diode. Then for lower currents, Level 2 approximations.

I also learned from 10 yrs with custom LEDs at source in my early retirement that all Diodes have a thermodynamic property related to chip size and case size for thermal and electrical bulk electrode-semiconductor interface resistance. It is my Rule of Thumb to say Rs= k / 2Pmax +/-50% typ. for a give package Pmax rating at Tj=85'C that the diode incremental resistance then dominates above ~ 10% of the rated power for most component designs.

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-334-power-electronics-spring-2007/lecture-notes/ch16.pdf

For Math you can learn for free online at MIT https://ocw.mit.edu/index.htm but there are better books

such as Getreu's who worked at Tektronix in the 70's

https://picture.iczhiku.com/resource/eetop/WyKtDIrFQPigHMVB.pdf

 

[HighTechPower]

I only took 4 years of physics in the early '70's in EE, enough to understand some fundamental behaviours but never smart enough to use it at a research level. My expertise was from learning it the hard way and then being able to convert higher order nonlinear behaviours into 1st or 2nd order linear characteristics, which is not the rigorous math approach of physics, just the application of it

Same here, most of knowledge & practice I gained by self study & experimenting from own income or pocket money. But I think there is a limit of self study & you can exponentially increase learning curve if someone else also could teach you.

 

[D.A.(Tony)Stewart]

Same here, most of knowledge & practice I gained by self study & experimenting from own income or pocket money. But I think there is a limit of self study & you can exponentially increase learning curve if someone else also could teach you.

Yes I was lucky to learn from a Gold Medalist in 1975 when I started at Bristol Aerospace R&D , yet I had already read every trade journal magazine at Uni. with electronics examples and knew how to do simple design when I graduated then within a couple years invented a SCADA design for nuclear reactors.

I'm sure you understand learning is a journey that teaches us to be humble knowing that, the more you understand, the less you know. and the more there is to know

My 2nd son is on that path having read Hawking's books before he was 10 and believes he can unify all of physics, chemistry , nano & astrophysics with a theory of everything and translate or reverse engineer what the Mayans knew, long before Galileo and Newton much later.

for fun http://www.falstad.com/mathphysics.html

 

[HighTechPower]

Hi. As references I used previous design of a YouTuber Skullmanhobbyelectronics and some application notes in drawing schematics. I'm waiting for someone to post his evaluations.

Hi. It's typo error. YouTuber name is Scullcom Hobby Electronics.