PWM vs LINEAR, which one should I choose as a Bench Power Supply? - Page 1
Forum section: electronics / beginners

author: Azhar
author_rank: Regular Contributor
timestamp: September 19, 2020, 05:43:00 am
content: Want to build a bench power supply, and would like to know what are the cons and pros between a Switching power supply and a Linear one!Thanks

author: ledtester
author_rank: Super Contributor
timestamp: September 19, 2020, 06:25:59 am
content: A linear supply is going to be easier to build.What do you expect to do with the supply? What voltage and current capability do you want? How much electronics building experience do you have?If it is your only bench supply I would go with a linear one. A dual 20V/1A supply with current limiting would be fine for a first bench supply.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2020, 07:28:57 am
content: A linear supply is much easier to build, at least at low to moderate power. A linear supply is usually also lower noise and faster reacting.The main downside of a linear regulator is that it produces quite some heat and the classical 50/60Hz transformer is heavy. At high power ( e.g. > 50 W) this can make the switched mode supply cheaper and worth the extra effort in the circuit and with EMI.For a first try one should go with a low power linear supply: it is relatively easy and enough to learn the basics. With modern electronics one rarely needs high power - more like a 3rd supply.

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 19, 2020, 02:14:13 pm
content: buy or build the analog one for small currents (with cv/cc protection) and buy the smps one (fixed or variable, upon your demands) for pumping real current after you promote yourself to medium>advanced electronistsometimes in this business you need 30-50 amps, that's smps days now.analog is more lab stuffI was testing hundreds of intelligent motor controllers with dsp or microcontroller core (like 30-80 at once on the power bus) using smps power supplies, never had a failed board from caused by the ps.is the board is correctly engineered it works with smps, like all the stuff in our houses, smartphones, tablets, laptops.....real analog good PS are for lab dev nowadays, for those rarely delicate loads.regards,pierre

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2020, 06:15:17 pm
content: Just a short warning: the lab supply design starting in video 221 did not work well. Combining constant current and constant voltage mode is tricky. A voltage regulator like the LT3080 is not as robust to odd loads as a lab supply should be.

author: fsenseman
author_rank: Newbie
timestamp: September 22, 2020, 07:09:37 am
content: Quote from: Kleinstein on September 19, 2020, 06:15:17 pmIs there a project you recommend? My skills are at the beginner level, I have the tools needed to build most small projects. I have a Korad KA3005P on my bench already and I'd like another supply for when I need different voltage/current levels. Thanks!

author: ledtester
author_rank: Super Contributor
timestamp: September 22, 2020, 07:57:00 am
content: You might be interested in this design:https://youtu.be/jBtNH1EbU8MIt uses the dual LM317 idea to provide current and voltage control - the one in the datasheet.The voltage tracking and DPDT switch on the output is convenient for op-amp circuits.He does some performance comparisons of it against a Korad and a cheap switching 30V/5A supply in this video which is instructive in and of itself:https://youtu.be/RdT-xWC4h4k

author: xavier60
author_rank: Super Contributor
timestamp: September 22, 2020, 08:59:04 am
content: A little more complex and not really suitable for an absolute beginner, the design in this thread is capable of good CV and CC performance.https://www.eevblog.com/forum/projects/how-this-linear-psu-circuit-works-and-why-it-doesnt/A few variants of it have been successfully built including by myself.

author: fsenseman
author_rank: Newbie
timestamp: September 22, 2020, 12:34:23 pm
content: Quote from: ledtester on September 22, 2020, 07:57:00 amI've watched the videos and now have something to aspire to. This looks like a fun project, I'm going to have to figure out how I'm going to do some of the case work given what tools I have available. Oh, so much to learn and oh so fun!Thanks again!