I once tried prototyping a 1A buck LED driver that operates at around 1 MHz on a bread board. This ultimately drove me to begin my bachelor's degree in electrical engineering because I had no idea why the heck this just wouldn't work! Today I do know why... =D

@After_Tech_Industries

Жыл бұрын

What wasn't working? I presume that it might have been the frequency; but I still want to know!

@jostsalathe

Жыл бұрын

@@After_Tech_Industries To be honest, I never actually checked what was the problem. So "Today I have some ideas why" would have been more correct. I think the main reason was the high contact resistance in the bread board contacts along the high frequency, high current path. I think the losses there probably screwed up the feedback loop of the regulator. Another probable problem was that the MIC2301 driver chip that I used has an integrated high side switch and therefore its SOIC8 package has an ePad at the bottom for cooling. The SOIC adapter board I used didn't connect to that, of course. I think it then also overheated way more quickly than I expected.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

I was researching the different topologies to decide which one to design a low-voltage DC UPS around, and kept hearing that SEPIC is unstable against transient loads. It'd be interesting to see a video on how different topologies react to different types of loads.

@FreeTheUyghurs

2 жыл бұрын

Hey sounds like the situation I found myself in too! Surprised there isn't more commercial options around this given how often you'd think home users would just want an uninterrupted DC power source for their home network and other DC-powered electronics. My setup at the moment is a small server rack with a 15V DC PSU and a 12V Lead Acid battery (+ battery tender) with their ground connections tied. The output voltages are separated by diodes, thus creating a sort of "OR-ing" device. That gate's output is connected to a powerpole rigrunner so that I can split all my components to separate SEPIC converters to ease the change in load and to also not have a single point of failure. So far so good but then again I'm only running raspberry pi's, switches, and a router at the moment.

@kenmore01

2 жыл бұрын

My experience is any SMPS will be unstable with transient loads. Go ahead and use one, but either have a huge cap, a battery or some other stable transient source to keep it from blowing out your electronics, or add a linear low-drop-out regulator at the end. It could even run saturated for low loss, but will prevent the voltage from going too high. That said, I suspect this SEPIC is worse than most SMPSs.

@profdc9501

2 жыл бұрын

Many power supplies are based on a dual control loop topology, with an outer loop with conventional voltage control PWM and inner loop based on current mode control. This tends to protect the power supply against transient loads, especially short circuits and the like. Something like UC3843 and like series of chips may be more stable with a SEPIC converter. There is a sense resistor in series with the source of the switch to control switch currents, and there is an outer control loop that senses the voltage.

@Teth47

2 жыл бұрын

@@chaosdragon6718 These are the reasons I moved away from SEPIC topology. I'm currently exploring flyback and push-pull, but stepping from designing buck converters to these more advanced topologies is pretty daunting.

@k4be.

2 жыл бұрын

There is also a four-switch buck-boost converter. Maybe look at BQ25713 for an example.

Your videos are truly informative. It provides me with a lot of electronics knowledge as a hobbyist. Keep going. Also get well soon. You are great, scott :)

@greatscottlab

2 жыл бұрын

Thanks a ton

@vishnustechcorner3881

2 жыл бұрын

@@greatscottlab I'm so glad that you replied to my comment 😊

@jclowe735

2 жыл бұрын

​@@greatscottlab what is the amps of this and could I safely use something like this with a 12 volts 20 watts solar panel?

@manoelbrasileiro1127

2 жыл бұрын

Sure, they're very nice. But I think there's an error on the schematics presented for the DIY SEPIC (on 10:20): there's no connection to gnd for Q1 (and L2, C4, C5).

@ChristopherOYoung

2 жыл бұрын

Another great video.

SEPIC converters are great for applications where the output power is low. For higher power applications, there is the two-switch non-inverting buck-boost converter. It is simply a combination of a buck and a boost converter. When the input voltage is higher than the output, it holds the “boost” switch open and modulates the “buck” switch. When the input voltage is lower than the output, it holds the “buck” switch closed and modulates the “boost” switch.

@yeyuan6273

2 жыл бұрын

it will be priblematic in between, .....

What I like about this design is the "self destruct" protection capability: One of my biggest fears when using Buck Converters specifically is that, when the switching transistor fails, it will most likely go shortcircuit (which in buck converters means the full input voltage will get to the output) destroying the load with overvoltage. In contrast, this design will not only let the voltage go low but also may just blow a fuse or trigger an overcurrent protection. This feature/bug is also present in synchronous buck converters: if one transistor fails, as soon the second one turns on, the whole thing will just go shortcuit and trigger a protection system before the output voltage can get high enough to kill the load. But maybe I've too much of a green mind for a disposing culture society?

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

I don’t think I understand more than a small bit of your KZreads but I watch and rewatch and even if I never understand I enjoy your drawings as much as anything. So clear. Your KZreads are art.

Great video Scott! I suspect your ferrite toroid had issues due to saturation, due to the uni-directional currents in it. Either add a small gap by using a multi part core, or go with high permeability powdered iron.

Ah yes another great scott video! Awesome video,very informational about the sepic convertor!

@greatscottlab

2 жыл бұрын

Glad you enjoyed it!

Another great video! What I always love , is the use of paper, pen and markers!

Some years ago I designed and built my own SEPIC converter, and used an off-the-shelf part for coupled inductors with one core. Before I built it, I actually did simulations of coupled vs separate inductors and it helped the ripple out a bit. Once built, it worked quite well. My board also included a Ćuk converter which is basically when you take a SEPIC and swap the placement of the second inductor and diode, resulting in a negative voltage with very similar specs. Made for a nice stable+versatile bipolar +-12V supply.

Your videos are delightfully concise with surprising details and always inspire greater things

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Hi Scott! Thank You for all the GREAT videos!! :-)

Great shot, Scott!!! Thanks.

Nice video. I've been using these buck/boost converters in my projects for several years. They work great, and allow you to use almost any DC cube power supply without worrying about input voltage.

Excellent video, Scott!

You have some of the best electronics videos.

@greatscottlab

2 жыл бұрын

Thanks :-)

Although I'm not an electronics guy, I like your videos a lot, because they are very informative and understandable.

I love using SEPIC in my designs. The biggest benefit is that they are inherently failsafe, there is no fault mode in which the input voltage can be on the output. Also if you need positive and negative rails, you can use the same regulator chip for SEPIC and inverting.

@MD-vs9ff

Жыл бұрын

C1 fails short.

@Niels_Dn

Жыл бұрын

There is a chance yes, but if I remember correctly from Siemens’ SN29500 the chance is relatively small. And then you can split up C1 to make the design even more robust.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Love your videos, it’s so simply explained yet very informative, I wish you could make more videos of coupled inductors since it’s a rare topic on the internet!

So informative , Thanks a lot man

It’s kind of amazing that buying two inductors is significantly cheaper than a single coupled one. I suppose there’s just not a big enough market for them to compete on price, huh? Super cool video! Especially the DIY circuit at the end.

@kenmore01

2 жыл бұрын

Winding a single is much easier than winding a dual with most winding machines.

Informative as always! Thanks mate!

Outstanding videos in every aspect AGAIN. I truly respect you.

@greatscottlab

2 жыл бұрын

Thanks mate :-)

Sir i love your hand writing

Very good video Mr Scott.

I'm looking at the schematic with coupled inductors and it appears if you remove the coupling capacitor you end up with a flyback converter. It just goes to show that all the different DC-DC converter topologies are actually very similar in operation.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

nice, often i see boost buck and sepics being combined IC that efficiency seems low tho at 60% a LDO may be better ( if it is lowering) Also maybe make a video about the energy efficiency of all those converters .

Great video Scott. I learned a ton. Next week your prototype PCB will be shipped by your sponsor JLC PCB I guess ;-)

Great video. Can you compare the SEPIC with the non inverting buck-boost to see which one is mor efficient? Thanks.

This is without doubt a very useful project

@greatscottlab

2 жыл бұрын

Glad you think so!

Thanks for All your video's. I have a SEPIC converter in Simulation program LTCad XVII. But NO matter WHAT i do, the current through the LOAD is Reversed. Till I saw this Video ! With D2 connected between Vcc and GND. NOW it Works ! Great Scott !

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Your definitely one of the most intelligent you tubers lol. Live your channel. When I finally get my parts replaced and back too work I’m definitely funding your channel lol. Ty for your time and research my friend.

@greatscottlab

2 жыл бұрын

Awesome! Thank you!

@farosrohmangeloraramadan3897

2 жыл бұрын

@@greatscottlab Next project Cuk Converter pleaseeeeee

Awesome and very well explained. Great Sunday afternoon entertainment !

@greatscottlab

2 жыл бұрын

Awesome :-)

Hey, your voice sounds like you are (recovering) from sickness. I wish you the best!

I have alot of experience with SEPIC and Cuk converters. Coupled inductors are great. They can be more efficient (alot of variables there though), they have better dynamics (dual inductor SEPICs and Cuks have some high frequency resonance that can make compensation harder), and the overall solution size can be smaller than for dual inductors. What I've seen is for name brand (like Coilcraft and Wurth) inductors, prices are comparable between two singles and a coupled. But the market for singles is bigger, so its easier to find other manufacturers of singles. Also, worth pointing out that I've heard Dr Cuk is adamant that a Cuk converter built with a coupled inductors isn't really a Cuk converter.

@Blox117

2 жыл бұрын

lol "cuk"

@ccoder4953

2 жыл бұрын

@@Blox117 It's named for en.wikipedia.org/wiki/Slobodan_%C4%86uk . Funny name perhaps, but he's Serbian, that is his name, and that is indeed what it's called.

@triffid0hunter

2 жыл бұрын

@@Blox117 Apparently it's pronounced 'chook'

@Blox117

2 жыл бұрын

@@triffid0hunter oh i see, there is an accent mark

@yeyuan6273

2 жыл бұрын

dude, the sepic is noesing as fk, but i have to use it, how to reduce the ripple to 5mv under 12v at 3a? i have tried everything........rc lc re apsorbtion, comm choke, what i did wrong? it keep around 100mv at 1a ar 12v, i cant knock it down further.......

I think you can build a boost converter circuit on a perfboard but you must put the components much closer together, the distance you use wouldn't work properly on any PCB type I think. All datasheets of switching power supply IC's are always hammer on that you must keep the loops as short as possible.

Perfect video! Thank you!:DDD

Amazing channel, super video!!

@greatscottlab

2 жыл бұрын

Thank you very much!

Interesting. Do you have a video on that device with the display and the fan/heatsink?

thx for ur videos. will watch

I am your big fan great scott

Also USB 1-30V CC CV converters are using SEPIC topology. They are really handy to use, but the efficiency is about 60%

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Very enjoyable video. Best regards Chris

@greatscottlab

2 жыл бұрын

Glad you enjoyed it

Fantastic video, dude! Thanks a lot! 😃 I'm definitely going to look around for those!!! Stay safe and creative there! 🖖😊

@greatscottlab

2 жыл бұрын

Thanks! You too!

Hello from Georgia, USA! I really appreciated this video. I do have a question that I would like to ask. I'm adding heated seats, grips, gloves, and primary clothing layers that will run off of my bike for cold weather riding. The bike has very little extra power so I'm changing all of my lights to LED and I want to use a solid state timer for the signals rather than simply adding resistors to prevent hyperflash. Most of the heated element controllers use a resistor for the lower temperature settings. It seems to me that I could use one of these boards to control the temp and actually conserve amps by using a lower setting If my gauge showed a constant draw on my battery rather than a 2a or so charge. Am I right. I'd use the FP5-139 to get the most out of each amp put out by my charging system.

Nice work👍

Eagerly looking forward for next episode of "Diy or buy" as frequency modulator ( FM radio)

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

hi scott did you make board with automatic li on charger with load sharing or power path function ? powering your project automatic while its connected to 5v usb and without damaging battery

I'd guess that a specific boost or buck circuit is more efficient, to take a simple example in a 12V to 24V boost, half the output power is coming directly from the input, while it's a bit less than half in a 12V to 5V buck

Beautiful video :) ...at 10:21 is there a missing Gnd potential at the mosfet ??

3:00 your Bosch washing machine is done.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Hello Scott, how you made your beginning perf board logo? You connected your LED's in parallel or series?

Very interesting. Thanks for the content.

@greatscottlab

2 жыл бұрын

My pleasure!

having a capacitor in series protects the output incase the buck transistor fail on a short but doesnt the capacitor limits the amount of current in a sepic converter?

I'm thinking the Prof. Slobodan "Cuk" converter deserves a thorough review. Somewhere I have my first power supply kit I built, a SEPIC-Cuk split rail design to emulate a low power computer PSU and I'm trying to recall what specifically. Man, I forget, seems like something maybe SDR related though I forget. Neat design.

Where do you find the silver copper wires you use? I haven’t be able to find them for years now.

Nice job 👍

I would love to see a video about vacuum flourescent displays!

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

( 1:21 & 6:22 ) I have used a SEPIC voltage converter that uses a coupled inductor and it has some decent efficiency and also has some protection features which is nice. The only concern I have is the EMI it might be producing specially I used mine on an audio amplifier build and it has some weird issues "sometimes" specially on its aux mode, might have to some tests on it to confirm those thingies.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

I would have thought the two coils in close proximity would couple anyway. Perhaps not as tightly/efficiently as two windings on the same ferrite ring, but... it's something?

Very good video Mr Scott. please what is the link for the module you recommended?

Is it just a mistake on your DIY schematics or source of Q1 is really not grounded? How the DIY version compares to the others when it comes to efficiency? Great video, I love your videos on power converters. Very educational.

I actually built a SEPIC converter on a perfboard recently. It can output up to around 50W of power and comes with an efficiency of around 80-85%. Anyway, great and educational video!

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

I need that buck boost converter, but I need a very small one for a drone, do you a circuit diagram?

The SEPIC buck-boost design is more elegant than I expected it to be.

Moin, I have a question regarding buck/boost converters. I have one of these standard 9(or 12, or 24)V DC Plugs. But if I hook them up to a buck boost converter, I can change the output. The output voltage stays constant at 9, 12 or 24 volts. The converters are otherwise okay. I can change the output of these fancy USB c PD boards, but these DC plugs just don't work :(

What happens to efficiency if you make it synchronous? I’d think you’d get it way more efficient. I’d love to see more videos on boost/buck with ultra high efficiency for sure.

@chrishartley1210

2 жыл бұрын

Synchronous 4-switch devices are much more efficient and can handle much higher currents. Of course the down side is that they are much more expensive and are also becoming quite hard to find. My preference for stable voltages with very little ripple are ones based on the LTC3780, the output is so stable that I have very successfully used them for mobile radio, something which is near impossible with most non-linear converters. I realised early on that Sepic devices would not be adequate.

@jameshancock

2 жыл бұрын

@@chrishartley1210 ya a full bridge is a solution but the problem with full bridges is that they require p channel high side which means you can’t use ganfets. I’m wondering if sepic with the diode replaced with another fet woold get you to n channel nirvana.

@chrishartley1210

2 жыл бұрын

@@jameshancock The 3780 (and 3789) drives 4 N-channel MOSFETs.

@jameshancock

2 жыл бұрын

@@chrishartley1210 wow. Gotta see how they do that because a pump can’t work so how are they keeping the top fets open 100% of the time?

What a great information 😯😊👏 thanks

@greatscottlab

2 жыл бұрын

Glad it was helpful!

Thanks man

@greatscottlab

2 жыл бұрын

You're welcome!

Have you considered using a synchronous switching configuration rather than the diode? Perhaps that would give you a better efficiency payoff than using the coupled inductor.

@yeyuan6273

2 жыл бұрын

using a transformer ensure 5percent increase, lossen coupled one gives anther 1percent boost, a llc typology needs pmos, or bootstrap, whichs means bad, really bad, especially in boost condition.......

I was wondering if I could use a filter choke as a coupled inductor?

would be awesome to see your thoughts on the sw2303 with power distribution

Cool video, thanks as always! =]

@greatscottlab

2 жыл бұрын

No problem!

I'm designing a power supply around 60v. Will this design be able to withstand 60 volts? What changes are needed to get there?

Can you tell us how good R how bad is it to use a 555 timer as a buck converter ( with feedback ) in detail ?

Very informative video, congratulations! I can't find the link for your chosen convert, can you give me here. Thanks.

nice job

Whats the name of the device with the big heatsink and fan with a bright whiter display which you use to test the load

Thanks for the video, it was very interesting to see a different approach, perhaps you can help me with a problem, I want to make an 18650 12v power supply to run an emergency LED light, so do I put three 18650 in series to give me my 12 volts or do I put my 18650 batteries in parallel to give me 3.7 volts and boost that voltage to 12 volts, any suggestions for the best method? Thanks, Bob in the UK

@greatscottlab Do you know if aliexpress has any variable power modules that can be controlled though i2c.. I want to make a i2c controlled bench power supply. Maybe modify the Dave Jones PWM supply, using a i2c PWM servo controller and ADC feedback to make sure the output matches what you asked for.. and make a triple output supply

¡Gracias!

@greatscottlab

2 жыл бұрын

Thank you so much for the support :-)

I would like to know if there's a current limit to them or can I send alot of amperage form one?

Interesting video👏. Can I use SG3525 ic instead of TL494 ic for the DIY version

very interesting video.l really enjoyed the premise of the video.

@greatscottlab

2 жыл бұрын

Glad you enjoyed it!

Not sure if it's a SEPIC but I have a Zk-SJVA-4X buck/boost converter (outputs up to 30V, they say it can take 50W with proper heat dissipation but idk whether to believe them) that uses two wires wound around a single ferrite core.

For higher currents, a 4 switch buck-boost will always be the better solution. SEPIC (as well as inverting CUK type ) switches VIN+Vout on its switch node and carries the large du/dt EMI problem. And you switch more current than Iout. That to a much larger Hot loop which includes the SEPIC coupling capacitor. In essence, you store the complete transfer energy in the inductive components so those inductors have to be sized that way.

@anwin85alon

Ай бұрын

pm me can you to install do sola paint of charger*

Nice

Is this commercial Buck converters are coming with close loop control (I mean, is it change its duty according to the change in output voltage? As we know, the output voltage may change with change in load. Please, give your thoughts.) Thanks, in advance

@nickpayne1182

2 жыл бұрын

That sounds like a constant current/constant voltage (CC/CV Buck) converter. The LM5117 is just one example, but I bought some cheaper ones from Amazon years ago because I needed constant current control for running LEDs. They use feedback loops to monitor current & voltage.

Hey GreatScott! Would it be possible for you to make an adjustable 100 watt output RF amplifier useable frequency range of 7mhz to 30mhz with the input being 5-10watts. Would love to see a video on this as i’d like to make a diy amp for my ham radio.

Any improved eff if you ran 2 buck boost converters in parallel to one load?

Nice video

Love your channel! qestion: can you make a cheap/ceapish "garden light mppt "low Voltage battery/supercap?

TL494 is awesome choice. You can even make ~240V DC boost to drive vacuum tubes. Not recommend for beginners, but you can check out Mr Carlson's Lab.

Damn... the comment section is moved again. As usual, great content, Scott ! Wish I could do something with this but nah, not even my profession neither my job, still watching this xD

Get well soon brother ❤️‍🔥

@greatscottlab

2 жыл бұрын

My voice is already much better :-) Thanks.

Very interesting! What other buck-boost converter designs are there that are more efficient?

@revimfadli4666

Жыл бұрын

Dahono converters?

I found a moderately high power (5a or 60w) buck/boost converter. What I found was a decrease in efficiency, increase in heat. My aim was to power 4g modem/router on boats, which operates in high temperatures (on sea, on summer, in Turkey). Boats are like cars, while engine is running voltage contains lots of jitter due to charging alternator. And just like cars, in small boats there is not a service battery, which means while engine is not running voltage is 12v. While starting the engine, voltage can drop down to 10v. While engine is running, there is a lot of noise (or jitter) and voltage is 14.4v. My solution was to use two coils, then a group of capacitors then a boost converter (increases the voltage to 15v) then a buck converter (reduces the voltage to 12v). 🤣😂 This devides the heat dissipation, reduces the jitter and just works... But in lower power applications (like 1-2amps) buck-boost converters works very nice.

@adamrak7560

2 жыл бұрын

This is a bit silly because the 4g modem/router internally has buck converters, which you obviously cannot get around, so you are forced to use this roundabout way. High freq, and highly integrated GaN buck-boost would have worked for you well, but this tech is not very widely available yet, and probably more expensive than chaining two very simple converters like you have done.

very interesting video

Great.. too much information..i learn new..thanks a lot for such a good video..

Please explain where the input and output are located on SEPIC