Power Supplies: Switching vs. Linear
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- čas přidán 18. 02. 2018
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Power Supplies: Switching vs. Linear
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In this video we look at the design and differences between a switching and a linear power supply. We examine the pros and cons and look at which one is best for which application.
Pevono PS305 Switching Power Supply $62.99 - amzn.to/2sHb7Wl
Volteq GPS303D Linear Power Supply $89.95 - amzn.to/2Cw0GUY
www.patreon.com/learnelectronics - Věda a technologie
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.
learnelectronics . I wasn't going to say anything. because I knew what you was meaning to say. and I knew you know your stuff. and simply misspoke. you had me at switching power supply. I clicked immediately. great simple explanation!
Not a big deal unless your a absolute newbie!
I was wondering what was wrong. I immediately imagined a newbie pulling his hair out wondering why he was still getting AC from the secondary...lol But I'm glad that I found you - I think I'll subscribe.
Its difficult to make a video without mistakes. Especially one being made for fee or close to it.
Perhaps one day there will be an edit function without deleting the video and re-uploading.
Switching dc power supplies has
output Vo1 is regulated.Is it possible to have all the outputs regulated not just one?
I too never really knew the difference between the two. Good to finally have it explained so succinctly. Thanks for another learning experience!
Welcome
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.
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.
Great video describing the comparison between the two. Having the scope really provides a visual element to help the confused understand.
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
I got me an industrial 24V one like that. When I saw the 3/8" nuts for the wire hook up, I knew this will definitely put out the amps it says it will.
Thank you. Very easy to understand.
Thanks for this incredibly informative video!
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.
Thank you, and I agree. When you get into the RF region, a linear supply is a must.
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.
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.
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 !!
Linear is best for radio. But there are some new switch mode supplies that have a noise offset potentiometer. It changes the switching frequency.
Very much informative.....thank you......I was looking for it👍👍👍👍
Great video! I didn't know the difference.
Thanks for your video and a time you spent on video. Gr8 video.thanks again. From India
Sweet and short. Thank you
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.
Heck yeah, I'll see if I can get one.
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 Nice And Calm Voice ! Relaxing !
Thanks! Nice info.
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)
Ha yes I thought that too. Misinformation.
Very good. Thank you.
Ricky from IBM
Sir can you explain please, can both do the Brute force method on fault finding on MBoards repairs ex: laptops etc.
Excellent explanation ☺️
Wait, the xformer doesn’t convert ac to dc, the rectifier does
I was going to see if anyone other than me caught that - the diodes depending on how many used converts to a half wave or full wave Pulsed DC.
Yes yes I mispoke
Yes, this guy does not know what he is talking about. In addition to what you said, how can DC have a frequency????
@@somebody2600 because it can be pulsed... a flyback transformer literally outputs high HZ DC pulses..
thanks . I learn a lot from you .
Very helpful.
Hello, which type of PSU you recommend for a He Ne laser that draws 18 Volt 0.1 to 0.3 amp?
Thank you!
Awesome Video again...
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
Thanks for this video
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?
For auto repair, it really shouldn't matter.
@@learnelectronics Thanks for the quick reply, but it's stereo home audio I am interested in not auto. Thoughts?
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 :-)
Thank you
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?
Thanks so much!
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.
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.
Unless you are dealing with turning your LED's on and off in the 500KHz+ region, an SMPS should be perfectly fine.
Ok thank you again keep up the good work
Thanks
Thanks guys
Ameritron has linear amplifier sets with linear and switching power supplies. What effect to the transmitting, the 60% efficient linear has? Thanks.
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.
Yes, my mistake.
I appreciate the smps diagram thanks a lot
Noise explanation is good. I like it. M
Thank you
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?
Does it affect tube audio preamp ?
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.
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.
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 :)
Yes, I made a mistake. Rectifier dos AC to DC.
Can we suppress the noise on a switch mode power supply ?.
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?
I would go with the linear supply.
Should I go for linear power supply for Laptop Repairing?
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.
SMPS into high frequency filter into a voltage regulator will give you best of both worlds.
@@1900OP thank you sir..
But it already has voltage regulator, and still make some harmonics in sinwave voltage since it's switching type.
@@atenglenon Voltage regulators can't filter high frequency components well due to parasitic capacitance from input to output, so you need an LC filter somewhere in that path.
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.
Thank you
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 .
Hello, today which would you recommend, the linear or the switched?
Switching if fine for everything unless you need an RF quiet environment.
5:58 - actually the Voltage Ripple is 5mV from Switching vs. 0.3mV from the Linear power supply.
Hi I am building my own switching supply I was wondering how I can clean up the output further can I use capacitors
Capacitors are the go-to for smoothing. Getcha big meaty 3300uF electrolytic cap rated at least 20% higher than you need.
learnelectronics and where exactly would this cap be placed can I put one on the outside inline with the positive power lead going out
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?
If it's a cheap one, it might, it will probably draw more current on the primary side and might fry your transformer or switching transistor.
Great video for me I burned many 2.2v smd led because they only can handle 20mA and the switching power supply keeps shooting high mA I will order linear
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.
Almost all modern amps use SMPS. The switching frequency is usually 150-400KHz, well above audible range. But if a problem occurs you can always top off your amp with a low pass filter set for the highest frequency you are interested in.
Thanks 👍
Best video.
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
Your psu is, most likely, outputting DC, is it not?
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.
For rf work a linear is always better. For af, either will do.
@@learnelectronics my use is a 3 ban dj isolator and my mixer does not have such a linear power supply plugged in the loop in out would a linear powered isolator make it better or i would not see such a difference if i do not mod my mixers power supply to a hand made linear,,,,,,,, which i am thinking of doing though.
People audiophiles rave it makes world if difference.
But im scared cause thinking the mixer was not made that way it might harm it if i do it this way.
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.
How cow. That's quite a comment. I think it deserves it's own video....
@@learnelectronics I corrected some of my sloppy typos.. Dosnt make the question make MUCH more sense but slightly more accurate anyway.. lol.. An that would be so awesome I'd be honored =D
@@learnelectronics Also, my days take forever now I'm so excited for the video an to try an solve this mystery.. (lol)Heads still gonna explode, watched dunno how many youtube vids, have like 50 open tabs just pouring over everything trying to find the answer.. I dun get how there is no explanation for this. I understand ohms law, just it gets wonky when it comes to this stuff.. An SMPSUs an such are basically the new standard so like.. where is the info? It gets even more wonky when it comes to trying to power LDs off SMPSUs, or tieing in regulator circuits in the SMPSUs to power LDs so they don't blow the LDs.. >.
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?
Rectifier is the first step, sorry for not being clear
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.
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.
You can to some extent, but the problem is not so much ripple, but noise. The PWM driver in these is operating in the VHF range.
@@learnelectronics I guess I don't understand the ripple/noise-removing effect of capacitors well enough. I thought there'd be some combination and amount of capacitors you could stick on the output such that they'd eat up any AC component coming out of the power supply.
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.
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.
Class H does not infer a 'switch mode' power supply.
@@seanmangan2769 okay, so how are you going to modulate a linear power supply? It's not a dual-rail, that's Class G.
Linear power supply is preferred for Hi-Fi systems. They tend to clean up some of that EMI/noise.
for me linear ones are cheaper, i can't get switch mode under 150€.. Is there any buzz sound comming from a linear one?
Sometimes
@@learnelectronics im looking for this one, just a eu version: www.circuitspecialists.com/csi3005sm.html it says ripple is 200mVp-p. How much is that compared to your switch mode supply?
Thanks 👍👏
No problem 👍
I think its very good and very perfekt. Tha same things I knew before.....But interesting! :)
And then comes the tough question: Can SM supplies be used for audio?
How do you know which is which when you have a power adapter in front of you.
The heavy one is linear.
Just checking but don't a lot of SMPS also lack separation from mains, while most linear are isolated from mains?
Yes, quite true.
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.
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!!!
Hope this helps: the difference is the number of cells. A battery is a collection of cells. A AA is a cell not a battery. A 9v is a battery because it contains many cells, dance for a 12V lead acid battery and lithium ion.
Wonderful. Thank you. I have decided to look in a different direction by exploring a Variable Adjustable 30V, 5A DC Linear Power Supply.
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.
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.
I must have gone to school on a different planet or an alternate timeline 8-O
Thank you for your knowledge you are a great guy would I need a 0.1uf capacitor for low frequency
.1 uF is a decoupling cap, you won't get any smoothing from such a low value.
Regarding to switching power supply, i may put a transformer 230v in and out 230v. It can be now called a linear power supply.
No, still a switching power supply, with it noise. Nothing changes.
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)!
Batteries are the ultimate linear supply
Exactly! ;-)
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?
Paul how would you use a center tap Xformer. One of my first projects went up in smoke....(I see you laughing)....
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.
cool
Transformers arnt used to to turn ac into dc.. usee to lower or raise voltage. Diods turn ac into dc
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.
A class D amp for audio?
@@learnelectronics Thousands of Class D amps for audio out there. My problem was finding a board that was NOT Class D. A lot of the tempting little boards from China are Class D. It means the outputs use isolated "grounds" so you can't for instance use a TRS 1/8" headphone plug into the output of those things if at some point its sleeve conductor also meets the common ground of the input circuit.
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.
Smps is female (making noise). Linear is male (multiple ways)
Switch modes supplies are superior, more efficient , less noise, less heat, generate greater current output from a smaller size, etc.
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
Power Supplies: Switching vs. Linearwhich the best to make
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