Power Supplies: Switching vs. Linear 

Towards the beginning of the video, talking about power supply theory I mistakenly said the transformer converted the AC to DC. That is of course incorrect. Thanks to those who pointed out my mistake.

I too never really knew the difference between the two. Good to finally have it explained so succinctly. Thanks for another learning experience!

I know I'm late to the party on this one, Paul, but fantastic as always. I really appreciate the diagram and straight forward descriptions.

Great video describing the comparison between the two. Having the scope really provides a visual element to help the confused understand.

I own both types but prefer the linear supply for radio transceivers. The linear supply will last forever with very few problems. The comparison was excellent, great video.

I scored an old hp linear supply for about 40 bucks from an estate sale. The thing might of been made in 1962 and is way to heavy to move around, its a beast of a power supply. Absolute game changer for repairing pcbs for me

Very nice job explaining this. You can get a very nice used name brand linear power supply with analog meters for about the same price as a new switcher. I have a nice 3A linear supply I got on EBay for $30. Nothing wrong with a switching power supply, I just like a power supply with a big transformer. Linear supplies are easier to repair too. Thanks for showing us the difference.

Thanks for this incredibly informative video!

Thank you. Very easy to understand.

Could you explain 'high frequency DC' it's HF AC until it goes through another transformer to be converted to the required voltage to be rectified back to DC is it not? please correct me if I'm wrong. (DC cannot be processed by a transformer)

Much thanks, very clear and helpful. Seems choices are very much use case/application dependent. In the world of modular synthesis, we much prefer linear where possible, but switching supplies are common because they are affordable.

Very much informative.....thank you......I was looking for it👍👍👍👍

your the man! just convinced me its a linear PS I need as replacement for ham radio station, old one gone duff & was tempted with small size of switched mode: not now !!

I am not new to electronics but up to now I had always compared the linear- and switch-mode power supplies only from the weight, size, heat dissipation, and efficiency point of view. In all these considerations SMPS was always the winner. Somehow, the ripple aspect on the output DC just fell by the wayside. Thereby, actually, it should be very obvious to all. Now, I will have to do more objective differentiation between the two types - depending upon the application. Thanks for a very nice video.

Thanks for your video and a time you spent on video. Gr8 video.thanks again. From India

Great video! I didn't know the difference.

Sweet and short. Thank you

Very Nice And Calm Voice ! Relaxing !

Excellent explanation ☺️

Thanks! Nice info.

Very good. Thank you. Ricky from IBM

Thanks for sharing your knowledge on this . I have been asking myself whats the diffrence for a small while as i have only heard of this recently . Defo a like from me :-)

I'm using a switch mode module with a DPS5005 regulator to adjust the voltage up or down it has constant voltage and constant current with all the protection

Very helpful.

thanks . I learn a lot from you .

Great video, have you any information on removing the short circuit protection on a linear power supply or make it switchable on/off ? Regards Andrew

Awesome Video again...

Sir can you explain please, can both do the Brute force method on fault finding on MBoards repairs ex: laptops etc.

Thank you!

Thanks so much!

Thanks for this video

Just what I was looking for! :-) Is it not possible to get rid of the SMPS noise by using ferrite beads and capacitors? I mean can you not do something so that you could use a SMPS in RF projects?

Ok thank you again keep up the good work

Nice video and explanation. What supply if your turning on and off a lot of rgb LEDs with let's say sound control? I had always thought switching for changing loads.

Thanks guys

Noise explanation is good. I like it. M

Great video. Thanks for clearing this up a bit. I am a newbie, and just getting into vintage audio repair. So, which would be better for that?

Suggest a good brand of power supply for charging lithium batteries? Which voltage and current rating one should buy for designing battery upto 48 volts? Which type: Switching or linear?

Hello, which type of PSU you recommend for a He Ne laser that draws 18 Volt 0.1 to 0.3 amp?

I appreciate the smps diagram thanks a lot

Linear power supply is preferred for Hi-Fi systems. They tend to clean up some of that EMI/noise.

the tekpower tp3005t is a ~$75US 30v 5a linear that is about 10lbs and 10"x 5"x 7.75"[it has a strong hand strap on top for easy carry] . when i was shopping i noticed these are popular with a lot of youtube phone/laptop repair content providers as well as diy electronic maker types. most of whom purchased the units. whenever i'm looking at units to buy i look at what is used by people who make their living repairing electronics as well as the diy & hobbyist segment. i've had the tp3005t for ~6 months and no problems yet. Paul, you mentioned 3 downsides to linear, weight, size, portability. this tp3005t matches a switching on all 3. you should see if tekpower would be interested in providing a test unit to appear in a future edition of switching vs linear review.

I looked at a Powerwerx power supply made for ham radio. It had spikes with ringing at 250 khz, 1.22 v peak to peak. This seemed not good to me because it represented almost 9 percent swing at 14 volts and thought there may be 3 volt IC's in the 7610. Wish I could send the waveform to you since I might be reading it wrong. My Astron was clean.

Overall, a good video. When describing the linear circuit however (@ 2:50) you suggested that, on the secondary side of the transformer you get DC. This is, of course, not the case: the voltage is still AC (just stepped down) and does not become DC until it has been rectified. Just thought I should clarify for those new to the subject.

Ameritron has linear amplifier sets with linear and switching power supplies. What effect to the transmitting, the 60% efficient linear has? Thanks.

Thank you

At this time November 2018 and back to this past summer, I can get a used BK Precision 1735A linear supply from a surplus store. 30V - 3A for US$91 / C$120. Weight 10 lb. I see them listed at Newark, etc. for $350 and up and even the national chain of retail electronics, Sayal, has a new similar spec supply of some name I've never heard of, they want $340 for. What I want a variable supply for is bench powering little headphone amplifier boards and other audio stuff that is generally battery powered and taking its input from wireless headsets. Some I want to see how they perform in gain, noise and distortion with different supply levels, because I have the data sheets for the main amplifier chips that show the allowed supply range and the output performance across that range. So I don't want a supply that could transfer noise to the wireless headset or to the amplifier board. I'm guessing these cheap Chinese switching supplies might be noisy. Certainly the reviews are full of units faulty right out of the box they came in or rely too much on digital controls that don't hold settings and end up frying your circuits under test.

Thanks for another great video. Just a quick question. In 2:45 you mentioned that in Linear Power Supply, the AC comes into the transformer and then we get the DC on the output which then gets rectified. Isn't the output of the transformer still AC but in the lower voltage? I think it's the rectifier that does the conversion. Sounds like a typo, but for a beginner like it can be confusing at first. I really enjoy watching your videos. Keep going :)

Best video.

Hi there , i think for laptop repair mainboard and mobile mainboard Linear is much better than Switching !! because Linear has protection on it and its secure for people doesn't have so much experience about electronic but Switching doesn't protection on switch off the voltage !! what do you think about that ? thankyou .

I'm looking for a bench top PS for mainly 2 applications, to power old 8 bit computers and also to revive 18650 lithium batteries...Which of these would be best for those applications?

Can you suggest a good model for starters? I am currently look to buy my first linear power supply for electronics projects and there is just so many to choose from.

Hi, would you mind to try modifying by add passive harmonics filter circuit in ps switching type? So we can reduce its cons. That harmonics effect.

A good switching power supply that has a clean output as a linear would, costs a lot more than a linear power supply. I chose a linear power supply because it is a simpler design. Good job on the simplicity of your video.

Wait, the xformer doesn’t convert ac to dc, the rectifier does

I think its very good and very perfekt. Tha same things I knew before.....But interesting! :)

Great video, Is it dangerous to run a switched PSU on lower than rated voltage? it is labeled as a 200-240v rated switched psu, how would running on 120 line voltage affect output wattage?

5:58 - actually the Voltage Ripple is 5mV from Switching vs. 0.3mV from the Linear power supply.

For aplication repairs mobile phone or laptop, linear power supply best choice

It is all about noise....most things it does not matter so much but in very low signal level, high signal to noise ratio electronics or analogue instrumentation it makes a MASSIVE difference. In these applications, linear wins every time.

Thanks 👍

I have the same question as another commenter, Fried Mule...why can't you just stick some capacitor(s) on the switched supply output to get rid of the noise? I guess it must be very difficult or else the supply would come with the caps built in and have no noise on the output, but I don't see why it's so challenging.

Should I go for linear power supply for Laptop Repairing?

So are switching power supplies bad for creating amplifiers?? Will there be noise and can you somehow filter it? My old amps are all using transformers and are heavy.. was thinking of constructing an amp as a project but not sure if switching power supply would be OK.

Back in the 1980's I purchased a 12v 25A Linear Power Supply (cost me nearly 300 dollars back then) from Tripp Lite for my Amateur radio. Switch Mode was still very new and back then it would tear HF up. I had a fire in my Apartment in 2006 and thought it was lost but I found it at my parents house in 2013 and I was relieved. This sucker is very expensive now and talk about heavy this sucker weighs a metric ton and if not careful could give you a hernia. Sadly I see computer power supplies that do 50-100 amps than this old thing.

Confused by your description of the linear power supply input stage. How do you get DC out of Transformer and if it's DC why does it need rectifying?

Why doesnt a 350 watt psu push a sub but a 10w bass amp transformer will. I was trying to hook the psu in line for power instead of the tiny "transformer" but the psu wont make a sound when hooked in. Went back to the the little thing and it pushes a 200w rms sub for some reason. Not much but it works which is suprising

do you know if the display color can be changed? or are they always the same color? i dont like red i like white! i think it easier to see! now some of them have different colors for amps/volts/power which is interesting but again i like white.

Hi I am building my own switching supply I was wondering how I can clean up the output further can I use capacitors

Does it affect tube audio preamp ?

Can we suppress the noise on a switch mode power supply ?.

Good video. Thanks. A lot of audiophiles use Linear power supply ( made by CI Audio or sbooster or uptone LPS) which cost anywhere between 350 to 550 USD with their devices like Ultrarendu and SOtM. They say it makes a huge difference in sound.

Hello, today which would you recommend, the linear or the switched?

Thank you for your knowledge you are a great guy would I need a 0.1uf capacitor for low frequency

Regarding to switching power supply, i may put a transformer 230v in and out 230v. It can be now called a linear power supply.

Im about to purchase an 3band dj isolator would the linear supply justify the extra cost to purchase it that way or the switch mode is jgood enough. All this Just mixed me up.

Thanks 👍👏

Isn't millivolts negligible for almost any and all applications? It looked so big on the scope then I payed attention to the actual rating(lol) 1mv. vs 3 mv . That's not like 3 vs 30 or 3 vs 10 even.. lol. I'm not nearly versed enough in radio stuff to know.. Is any radio stuff even that sensitive? Also, how does a power supply work.. Like I have a psu from a cpu and no matter what I plug into it or what resistance I put in line with it it'll only put out whatever the internal resistance of the actual device is demanding(it only will blow LEDS). The only exception to that I've been able to notice is if I connect a big DC 2wire motor, an even then it defaults to .300-.400 ma. I need to physically hold the motor to make it output more amps. (even tho adjusting a pot does hardly nothing but turn it on and off... I want to power a laser diode off this an it's all I got.. I don't get it. Can I just plug my diode in an it'll magically know it's ideal operating range? Why does it pretend resistance dosn't exist inline before that too? Am i witnessing some freak anomaly? Then follow up question: How does a supply FORCE more current/volts in if based off that theory and behavior you should be able to plug anything into a regular 120v rectified an smoothed single an that's it'll just magically draw whatever it needs as long as it's not over .4ma?.. Cause I'm told it's a switching power supply...Like if I add resistance to the motor I can get it to output up to 2A(should be putting out 12v @ 18A... or 5v @24A..) I dunno.. been stuck on this for weeks. WEEKS.. The more i think about it the more I'm going insane... Can't afford a decent power supply.. Wasted money buying a assortment of LM chips as I watched the video on them and using them to power a laser diode.. but I'm worried if I connect the computer 12v in to the LM317 it will get 12v @ 18A(well within V range but way above A range) an just fry.. or does that magical rule apply? And if so? Re-circle back to beginning.. lol.. help.. please.. like what power supply from mains is below 1.5A for the hobbiest/inventor? Or can I just plug my PSU into the LM317 laser diode power circuit, it'll auto sense it can output the full 12 but auto limit itself to only putting out what the chips max is? an if so.. how does a power supply FORCE more current in? see the circle here? Please. Help. lol.

What do you think of these new "Class H" amplifiers that have a switch mode power supply with multiple rails driving a Class A/B amp? Supposedly these are able to overcome the limits of the switch mode power supply by switching from the low power to the high power rails when more power is demanded.

It seems like linear supplies last longer. The linear wall warts I have from the 80s and 90's still work. Most of the featherweight switching ones I have from the zeroes have failed at some point. I'm sure these switching power supplies have a lot less copper and iron in them and save money on shipping costs, making them ideal for today's throwaway electronics.

for me linear ones are cheaper, i can't get switch mode under 150€.. Is there any buzz sound comming from a linear one?

various switching power supplies have different ripples peak to peak voltage and are at different Switching frequencies between 10K to 50K. When connecting various switching power supplies to preamp amplifier circuit the switching frequency and ripple gets amplified causing S/N signal to noise issues. How can you prevent this when using cheap china switching power supplies with preamp tube, op amp, transistor amplifier circuits to work with various switching power supplies?

Just checking but don't a lot of SMPS also lack separation from mains, while most linear are isolated from mains?

My limiting factor is usually cost I'm afraid. My wee home made switching supply does for most things. A linear supply would be nice for radio, amps etc but I'm afraid that batteries will have to do that job (for now)!

I must have gone to school on a different planet or an alternate timeline 8-O

I am in the infancy stage of Electronics 101. To this point, I need a major clarification on battery voltage. I want to use a 12V battery with a breadboard to closer simulate the 15 volts across the rails on a HO scale track .... My confusion: .... You see many of these tiny, rectangular, 9V batteries being used with breadboards. A riding lawn mower typically has a 12V battery which is considerably larger than the tiny, rectangular 9V battery, yet the voltage comparison is 9V to 12V. Adding to my confusion is a 12V car battery which has the same 12V rating as the riding lawn mower battery, yet the car battery is quite a bit larger and heavier. What am I missing that differentiates between these voltage readings: 9V rectangular battery versus 12V mower battery versus 12V car battery. Thanks!!!

Paul how would you use a center tap Xformer. One of my first projects went up in smoke....(I see you laughing)....

IMO linear is the way to go. I've had a lab setup since the 70s. A super clean linear supply will be something like 15v, 5a. Size of a rack mount CRT scope and weight of about 30lbs. My recently purchased Dr Meter linear PS-305DM, 30v, 5a I'm using to get a dead battery pack, hopefully, back up and running. Most likely the Dr Meter is the same form factor as in this video. One of the cells was ultra low at 0.014v. I chose to charge at 15mA CC and voltage at 0.50V CV. Took about an hour for the CC indicator to go off and the CV indicator to light. Gradually increased the voltage and current as the battery became charged. The linear might make a difference in very low output application as above and when powering very low power like devices like watches. The display reading did not suffer from any display jitter or bouncing digits during very low output. I've worked many years in power supply manufacturing, a maker that specialized in supplies only. I have a preference for linear.

And then comes the tough question: Can SM supplies be used for audio?

Another pro / con is: reliability / longevity. In my opinion: Switch Mode Power supplies are not as reliable. Especially is small cheap electronics, LED light fixtures, etc. SMPS for computers are getting to be pretty reliable.

How do you know which is which when you have a power adapter in front of you.

Switch modes supplies are superior, more efficient , less noise, less heat, generate greater current output from a smaller size, etc.

Power Supplies: Switching vs. Linearwhich the best to make porous Anodic Aluminum Oxide

cool

Transformers arnt used to to turn ac into dc.. usee to lower or raise voltage. Diods turn ac into dc

Smps is female (making noise). Linear is male (multiple ways)

The switching power supply seems no good for audio applications either. I hooked a similar one up to a little Class-D amp and it's fuzzier than a peach. Makes sense though, GIGO.

He just wanted to show off his sweet equipment

If i am dealing with audio stuff then definitely linear power supply. Noone really likes noise

"High frequency dc" is an oxymoron. dc is zero frequency by definition. The transformer alone doesn't convert ac to dc in your schematic for the linear supply. A rectifier converts ac to dc. And there's no discussion of the feedback loop you showed in the block diagram for the switching supply.