I am done with linear power suplies

Thread Starter

Bogdan.m

Joined Apr 20, 2019
13
Hello everyone, i am new to this forum, as the title suggests i want to make a decent smps let's say about 0-40v and 0-30A. If anyone has a working schematic for this and wants to help me build and troubleshoot the power supply once i start to build it, is more than welcome to join me on this quest and i would be very happy. Have a nice weekend everyone.
 

Sensacell

Joined Jun 19, 2012
2,564
The effort to build such a beast is 10,000:1 over just buying one.


Even if you mined salt in Ethiopia with your bare hands to earn the money, it would still be easier.
 

DickCappels

Joined Aug 21, 2008
6,187
If this is your first smps project perhaps you would best start out with a more modest goal, say 10 watts or less. Bringing up power supplies can be a dangerous, expensive, and painful job. Starting lower power designs is a good way to build experience inexpensively and maybe with a fewer burnt fingers.
 

Thread Starter

Bogdan.m

Joined Apr 20, 2019
13
Electronics is my hobby, i don't want to buy one. The smps does not have to be exactly like i said, it can be 30v, or 20A or any value close to what i said. I want to build this out of pure pleasure, to know that i made it. I made small smps like 20W, but i want a more permanent power supply for my bench.
 

SLK001

Joined Nov 29, 2011
1,543
Saying you're done with linear power supplies, is like saying you're done with your eyes, or ears, or hands. A linear PS is just another tool in your toolbox. For some applications, a linear PS is the ONLY way to go. They also have the advantage of being very simple to design and to get right the first time.
 

Papabravo

Joined Feb 24, 2006
12,906
Electronics is my hobby, i don't want to buy one. The smps does not have to be exactly like i said, it can be 30v, or 20A or any value close to what i said. I want to build this out of pure pleasure, to know that i made it. I made small smps like 20W, but i want a more permanent power supply for my bench.
If you refuse to listen to good advice there is not much we can do to help you. You have stars in your eyes. Whatever goal you have will be more rapidly achieved if you listen to @DickCappels in post #4, and get your head out of that dark place it seems to be stuck in.

You learn to do things in electronics by starting small and simple and building up to complex and difficult. You have your 20W supply, that's great. What is the efficiency of that supply? How could you make it better? There are many useful SMPS projects you can do on a shoestring that will teach you what you need to know. How to pick magnetic components is the big one along with low ESR capacitors. Next comes board layout. It is nearly impossible to breadboard an efficient SMPS. You must use a PCB. Without a deep understanding of these things your chances of success on a 1200W adjustable supply would be dismal.
 

MrChips

Joined Oct 2, 2009
20,231
+1 for everything everyone has said.

Linear power supplies are much easier to build and trouble-shoot. Switching power supplies are very difficult to debug because its operation depends on every component doing its job properly.

Switching power supplies produce a lot of high-frequency noise that is very difficult to remove in all kinds of applications, analog and digital.
 

Papabravo

Joined Feb 24, 2006
12,906
+1 for everything everyone has said.

Linear power supplies are much easier to build and trouble-shoot. Switching power supplies are very difficult to debug because its operation depends on every component doing its job properly.

Switching power supplies produce a lot of high-frequency noise that is very difficult to remove in all kinds of applications, analog and digital.
A study of passive filters to remove high frequency noise from power supply outputs is highly recommended. You could build an entire career on this one.
 

nsaspook

Joined Aug 27, 2009
6,914
Why is that?
For large inductive DC motor loads selecting/designing the right SMPS can be tricky. The SMPS supply feedback loop and a fail-back mechanism can freak (hiccup mode) with hard current limiting on startup (stalled current) when the motor shows a near zero resistance unless there is sufficient energy storage (as is usually the case in a linear supply) from something like a DC link capacitor after the power supply. You need one with really good and fast constant current limiting even at below 50% of rated output voltage.

https://www.microsemi.com/document-portal/doc_view/131948-an-8-hiccup-mode-current-limiting
 
Last edited:

ian field

Joined Oct 27, 2012
6,539
Electronics is my hobby, i don't want to buy one. The smps does not have to be exactly like i said, it can be 30v, or 20A or any value close to what i said. I want to build this out of pure pleasure, to know that i made it. I made small smps like 20W, but i want a more permanent power supply for my bench.
Apart from low efficiency - what's your objection to linears?

I try to avoid linears because they tend to cause cascade failure when the series pass element fails short circuit - buck regulators have the same problem.

Push pull forward converters are the way to go if you want lots of power, but flyback boost is much simpler for lower power. flyback is step up - unless you use it to drive a step down transformer.
 

Thread Starter

Bogdan.m

Joined Apr 20, 2019
13
i know that linear has some advantages over the smps, i mainly dislike the fact that it heats up when i draw a lot of power at low voltages, i could make a lower voltage power supply, but what happens when i need more voltage, keeping 2 power supply ? i really don't know what to do after reading all your opinions....
 

ian field

Joined Oct 27, 2012
6,539
i know that linear has some advantages over the smps, i mainly dislike the fact that it heats up when i draw a lot of power at low voltages, i could make a lower voltage power supply, but what happens when i need more voltage, keeping 2 power supply ? i really don't know what to do after reading all your opinions....
My box of left over wall warts covers about 75% of projects - sometimes figuring out what to do takes a bit more head scratching.
 
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