Hi Hero999,
Thanks for the warning
But i already now that, i dril out the holes around the 230V powerline connections before i do the real testing, this is only the reference section build.
This is not a final circuit board, i drill a lot in these boards, like in one of my high performance preamps to get the paracitics down.
If you want, take a look at this design of one of my low noise preamp, design for measuring at power supply's and some extra holes in the circuits board!
Date/time: vrijdag 17 maart 2017 16:35:45
https://www.circuitsonline.net/forum/view/135863Back on topic,
The most important point in the development of a linear power supply is the phase margin of the control loop.
A standaard opamp has about 60 degrees phase margin, every component you place in the loop will bring this phase margin down.
Placing a power transistor(s) in the loop brings it down, if don't place a capacitor over your feedback resistor, almost certainty there will be instability horror.
Look at the many power circuits on the Internet, most of them are compensated to "dead"...
This is because the person who developed the circuit has not understood how the circuit works.
Two examples, Dave Jones fist power supply, I knew from the beginning that it would fail.
He finally learned his lesson with version-2 :-)
The second example is e.g. Gerry Sweeney power supply, look at his video's.
Hi did a fine job, except for the loop stability...
Do not think that I am a gentleman who knows everything, as someone declaimed here on the forum...
In the beginning of the 1974 i started with opamps like the uA709,
my college and i were complaining about it alway was oscillating, what a bad opamp!
But of course we were bad technicians, we did not read the datasheet and aplication notes, we were fools.
Take a look at the LM709 data sheet, and see how universel this opamp is, even gains of 80 dB are possible with reasonable bandwidth.
Would I still use the uA709, no there are now much better opamps for sale, this was only just to make a point clear.
And regularly I have to learn, make stupid mistakes, I am just a human being.
Thus e.g. only using a fast opamp does not make a good power supply.
The intention is that when you develop the power supply, and that all parts of the schematic are well matched to each other.
The Harrison design i use (from the late 1950's) is really beautiful.
And my part of it, is using modern parts and tuning these for optimum performance.
All designs with extra transistor and opamps in the loop will never reach the performance of this simple design.
And again, most LAB power supply do not need this High End performance.
I have a Dutch famos brand switching power supply, 30V and 5-Ampere, the dynamic performance is "not so good", why?
There is a lot of capacitance on the output en the loop is not fast.
But i still use it regular wen i need higer currents then 1-Ampere and when its not critical.
The time is up, have to work, laters more.
Kind regards,
Bram