GreatScott: How to make a softstarter Also GreatScott: That's a subject for another video

Your content always saves me and my teammates right before working with some power electronics, you're a lifesaver

"stay creative " is the best dialogue you say. Keep up the awesome work

During my education we were taught about this. We were taught it was called a Startup Power Spike and most electronics are designed/engineered to reduce this but normally they remove the circuits in production to cut costs. I haven't done any of this in over 20 years but I still have my textbooks and notes. I miss tinkering with circuits. Thanks for the memories and the great work.

I love seeing these smaller but still very useful circuit projects. This is gonna be super helpful on my next project!

I love the solar system stuff, when I have my own "Lab" I'm going to do my best to power it in this way. Great video!

GreatScott is such a good teacher for learners to learn about something important

I really love the way you deliver content. For someone coming at this with a reasonable technical background, you deliver very relevant information in a very easily understood way. If I could make one recommendation it would be this: Don't change a thing!

Human, I understood everything you said. Because it is science!!!! You are my favorite youtuber human!!!

I enjoy these videos so much! Your presentation is consistently excellent and sufficiently detailed, and with very good production

I like the way everytime you write down and show us the practically calculated values of resistance, current and voltages

Man you're amazing, I spend part of my breakfast watching your videos, I find it clear and easy to understand thanks from a mechatronics engineering student.

This was really interesting, love how clearly you explain things!

Hey I noticed your videos have been absent from my feed for a very long time! Please keep making more content like this, it's super awesome as a hobby electronics nerd to see a master at work.

Why are u so gentle and genuine person? BDW i had this problem 4yrs back, while designing pwm controller for big dc motor drive. I've just use few passive components & added some start delay in microcontroller code, which was initiating pwms to drive H bridge.

ive been on a kick lately of taking apart every piece of electronic equipment i have laying around my house not in use and mining it for all its little components. Watching your videos give me so many ideas for what to do now with this box of random parts.

"I will see you next time" was bit energetic this time 😀

Most people: This electrical device doesn't work, I'll toss it and get a new one. Electrical engineers: Hold my beer...I'll make it work.

Got exactly these problems currently. You explain the problem and solution VERY well. Thank you!

Just built this for a WW2 dynamotor, and it works great, I was trying to find something to limit the current so that it’s not hard on a PSU if I ever get one for it, I will say your schematic is very well made!!! Thank you very much GreatScott!!!

I wouldn't have been able to design so many of my projects without this channel. Thanks for another great video :)

You may use variable R2 and R3 to adjust the time delay for charging and discharging the delay circuit thus making it adapt to different circuits configurations. Good job.

I just completed this circuit and it works like a breeze. I was trying to run a dc motor using atx power supply boosted by a boost converter (12v to 24 v). Initially, due to inrush current, atx power supply was getting shut down but now it works well. Thanks Scott!

Very tidy. I could never do your extremely tidy explanations. Congratulations!! Thanks for sharing your knowledge and experiences!!!

Slight error with your RC time constant: The resistance seen by the capacitor is the thevenin equivalent, not the series charging resistor. Your time constant should be 0.5s, verified in simulation

You can also use a coil in series and a protection circuit to discharge it safely ( diode and small resistor ). It's quite an easy and simple solution. Besides, you can also add in parallel a capacitor to with a resistor move all the high frequencies back to the source. These are pretty simple strategies most power supplies use.

I find these lessons very therapeutic and mind soothing..💆‍♂️

Years ago I wanted to make one like this, but with reverse-voltage protection as well and only solid state components, no mechanical relays, good job.

Good video on a common issue. I made a similar circuit several years ago for use on a 70A 24VDC set of motors I had to start with a 100A power supply. I really had to let the motors get well started before applying full power. I used a large high power 3ohm resistor and an electronic delay-on-make relay switching a larger relay made to withstand constant use at high current and temperature. It worked well. I've seen a guy build a similar device to start a helicopter jet engine. On mine, since this was used on a commercial project, I had to use modular components to allow for field service. I also included a one-shot temperature limit switch and yet another relay to ensure that if the time delay relay failed the big resistor couldn't overheat and cause a "thermal event" (what we called fires back in the day). I've also used NTC thermistors on things like 10-15A blowers that weren't a threat to the power supply but provided less of a challenge to my customers' often overtaxed circuit breakers. You want to choose thermistors carefully and use them fairly close to their rated power so that you get minimal voltage drop over them in steady state use. I look forward to your next soft start video.

I have absolutely no idea to what softstarter is, but I still watched your video as it is always very entertaining.

I enjoyed this small project, and learned something about soft starters and inrush current. Thanks for the great video!

Thank you so much for the well-presented KZfaq. I need to know a lot about soft starting as I am using four 3-kilowatt quartz infrared heaters, that can be switched with a remote controller, to one, two, or three kilowatts. I think that they all need a 16 Amp type C, circuit breaker. The standard circuit breaker trips immediately. On further research, I find that with a soft start, the extremely expensive heating tubes will last 30% longer. Now back to my experimenting!

Could you use an inductor to initially slow the inrush current and then when the magnetic field is setup allow all the current?

You say: "talking about electric engines.....but this will be subject for another video". Exactly what I wanted to ask you, perhaps using a circuit that excites the relay at the start, only for the time necessary, to avoid the continuous excitation of the coil, which could interrupt and generate malfunctions. thanks in advance for future projects and for sharing your knowledge

Really good study of the transient state in the inverter. Good design for the relay timer as well. 10/10!!

Extremely useful! Thank you! I have been in need of a soft start circuit for tube amps. Lots of capacitance on the front end, and it can be a massive current surge at turn-on. I have a few 220uF 700V film caps, and they pull so much current on power-on that they have smoked some pretty beefy resistors that could easily have handled normal current draw. I can also use this for loudspeaker delay circuits. You explained it very well.

Great ! Im waiting for motor soft starter description!

Greatscott : "don't hesitate to check JLC PCB....for their fast production capacity and delivery times!!!" ALSO GREATSCOTT : "MAKES HIS OWN CIRCUIT BOARD.".....TOTALLY SAVAGE🤯🤯🤔

awesome video. love how you explain all the parts and stages involved

So many concepts in a single video, thank you!

There should be a 1N4004 diode across R1, with cathode band to +12V. This will immediately discharge C1 and 'reset' the circuit if the 12V drops to zero. Thanks for the great video. 👍

7:46 in this case time constant is actually C * (R2 parallel R3)

Really cool :) This has been something I've been interested in for a long time, but haven't sat down to learn anything yet. Thanks for the video, it was great! I hope your comment about motor soft starters comes true.

greatscott, love your videos, half the time im lost with the jargon but always good to watch.

stick with the NTC but use it with the bypass relay. it's exactly what high end computer PSUs do nowadays to get over 90% efficiency ratings.

This is great, I like your basics videos more than large projects. But you made a mistake with the time constant, the equivalent resistance would be 50k because of the other resistor going to ground, which would give you a time constant of 0.5s

Such a miniscule thing, but so important like matter of life and death of electronic devices and components !!!!! Thank you so much for the insight Scott !!!!!

After watching your video's I feel like making something really cool... but then I come back to the reality that I only know how to change the batteries in a torch. I love watching your video's. They inspire me.

Nice video. Don't forget the A class amplifier. :)

Hi GreatScott, hope that you will very soon make a softstarter for ac motors because my lathe has a 10kW motor and trips the breaker every now and then and my dad doesn't really appreciate the flicker of the lights at the beginning. keep up these awesome videos!

Unlike the other channels I am watching, I consider your videos like reference study materials 👍 Good works bro

The issue is clearly explained, thanks for this great vidéo!

I love it! If you can expand this to an A/C circuit, that would be great! When a refrigerator (for example) powered by an inverter hooked to backup -power-supply batteries causes the inverter to shut down, that's a real problem. Yes, a larger (and more expensive) inverter is one solution; however, some type of soft starter is a more elegant solution. THANKS!!!

I would like to see you make a VFD!

What an excellent explanation! Thanks, here from Brazil.

🙏 i did enjoy the solution to the current switching problems, I also liked your over-all explanation 👍

Usually, your charger and inverter are both connected across the battery bank. You can also add a supercap to deal with fast, high amp loads like motor startup. Usually this would be how you deal with high amp draw. Not sure why it isn't working in your system. Is your inverter tied directly into your inverter without batteries?

Nice video, thanks:) It would be interesting comparing this solution with another that uses a MOSFET as the main switch to reduce even more the power consumption of the circuit. With a 12V DC link it shall not be a huge challenge for you ;)

Great work. You explain every part of the circuit with examples.Keep it up.

Thanks Scott! I'm going to implement this project circuit.

When you’re trying to make an arc lighter using advice from a GreatScott video but get a notification about a new video so you just go watch that one instead...

Would a large capacitor/inductor pair, with the inductor in series on the supply side of the capacitor, solve the problem almost as well? I'm not criticizing, I'm trying to learn. Thanks!

It was fantastic journey of 10 minute 31 second with you. keep it up and regards from India

Great Idea, I use this kind of automated system already since about 20 years for powering on transformers (fuse switched off sometimes) and yes, for PC's also. They have with their switching power supply also a lot of capacitance within their infeed circuit. Sometimes there are quite big sparks at the switch or even at the plug itself. One day in very past I even lighted up a fire in the socket while plugging in such a PC - cable. The socked was dirty, may have had also some invisible oil inside. The spark caused by that capacitance at the plug had been enough to light that oily dirty thing within the socket up and a great flame came out of the socket against me. That experiences caused me to solve that kind of risk.

Will an inductor in serial also solve the problem? An inductor will reduce the current surge.

I was not paying attention till I heard "my final solution"

Hi Scott Great Video. You could also use a low side Mosfet to limit the inrush current. The VESC anti spark switch is doing that in a good way. So no mechanical components are required.

Excellent and informative as usual. I'm looking forward to the motor soft start video.

I think is better to use an p-channel mosfet, is more power saving...

You have completed 1.1 m subscriber still not uploaded the drone video

Finally a new video, couldn't wait anymore!

Did a similar thing for a large variac, that would trip the main breaker at switch on. Just some 10W 12R resistors in parallel, with a thermal fuse attached to them, for failure protection. Then a simple capacitive voltage divider, driving a 24V relay after the bridge rectifier, with a 470uF 63V capacitor and a 24V 1W zener diode, along with a 33R 1W inrush limiting resistor for the capacitive divider. Relay would close contacts about 0.5 second after mains was applied, but enough time for the variac core to not saturate. All parts laying around, and worked well. Also added a voltmeter to the variac, as it had no scale, and made one out of an old meter movement, and as the variac can go to 360VAC, wanted a suppressed zero, so used a tap ( 60VAC) on the variac to derive a regulated 7V supply, using a LM723, and this was then connected to one side of the meter, with the other side getting a suitably half wave rectified output sample. Calibrated, remarked the meter and it works well.

can't u put a capacitor before the inverter switch to charge the internal capacitor off the inverter just enough to prevent huge currents spikes ?

softstarter can be find in high end inverter, but it's cool anyway to see how to fix that

I was just having a dilemma due to inrush current. Thank you for providing a possible solution.

I really liked the thermistor trick, but your criticism was very fair.

"the post apocalyptic inventor" did so ething similar but he used a 555 timer , but hus cirquit was also made for mains voltage

Can't we use inductor in series with appreciate value so that it will limit the inrush current and as soon as the voltage gets stable we will have no inductive reactance and hence no resistance/powerloss (except for resistance of that wire)???🤔🤔

Terrific video. I learned a lot. Your videos are always informational with minimum verbosity.

the circuit i have been using for a while is really simple. it consists of a P-channel FET a small capacitor and a couple resistors. the P-channel fet is wired as the high side switch with the source connected to the input side and the drain connected to the output. a small capacitor is placed between the output and the gate with a 100k resistor accross it to keep it discharged and a 10k resistor from gate to ground. when the device is powered the transistor is normally off since the capacitor which is place between the gate and drain starts a zero volts the rising output voltage acts as a negative feedback loop limiting the rate at which the output can switch on and once the capacitor is fully charged by the 10k resistor to ground the transistor will be fully enhanced and the output will be on. the rise time of the output can be adjusted by changing the feedback capacitor and resistor values. a zener can also be placed from gate to source to limit the voltage across it in cases where the supply voltage exceeds the gate - source voltage rating of the transistor. when the device is powered off the resistor across the capacitor will discharge it in a few ms so it is ready for the next power on. I first saw this when at university and thought it was a very elegant design that does not need and relays or complicated timing circuitry but can't remember what it is called other then P-MOSFET current limiter. but when checked on the oscilloscope it always produces a very nice perfect ramp up to the final target voltage which is the ideal wave form shape for charging a capacitor though there is a small jump from zero volts up to whatever the threshold voltage of the mosfet is so you should pick a fet with a low threshold to reduce the initial spike but other then that it works great.

Hi GreatScott... Is it possible to remove the relay and use only the mosfet.

Could you also put an inductor in series? Would be more inefficient I think.. :/

Your videos are very inspiring thank you.

We used to use 3 phase soft-starts on 130kw bore pumps. 2 pumps made one water screen. We had to turn each pump on separately so we didn't overload the supply. It was interesting to see the first kick then ramp up. The soft starts made great sounds as they worked until the bypass kicked in 🙂

6:30 great Scott has Germanys final solution.

Usually inverter is connected straight to the battery.

I use contactors for my "relay" due to my circuiys drawing hundreds of amps. I do like how yours is designed (almost identical to my design). Jeep up the good work Scott!

As always, great video, keep it up

Can we just switch on that switch based on the voltage of the capacitor? .. (using a comparator maybe) .. and avoiding the delay circuit entirely!

Thats why always the inverter go direct to battery and no to the charge controller xD

Edit at the bottom! Hi Scott, I'm looking for a softstarter for my parallel push pull tube amp and was glad to see you publishing this video. My problem is, that my relais activates instantly, as soon as I apply power (I'm breadboarding with 5 volts DC, 500 mA). Even with a 470 uF cap. I'm using a finder relay (40.61.9.012.0000), 100 k resistors and your suggested n-channel mosfet. I have to drive that softstarter with 6,3 volts later, because that's the only low voltage source in my mono blocks and I don't want to put something else in it (the less stuff in there, the better). I tried to reduce the resistance on the caps kathode but nothing changed. Hi, I found my error. It was in the voltage divider section and the connection to the gate of the mosfet. Had it connected the wrong way.

Thanks so much for sharing with us. As a beginner, I hope you can show us more on how you connect your test equipment to the project. Like the oscilloscope. I know that if project is power from AC and if the point is link to Earth. We can damage the scope badly. Thanks again. Enjoy your work a lot.

Wouldn't it be better to just use a MOSFET to bypass the resistor instead of using a relay ?

And next time a AC soft start pls😛

Great Scott! Another fantastic and informative video!

Nice - that's a elegant solution for a soft starter. I used a 555 timer in my home built power supply project 6 months ago. But I like your MOSFET with the RC network better.

An IRFZ44N seems overkill for driving a relay... why not something like a 2N7000?

Won't an inductor work as well as a resistor on the input to reduce inrush current ? ...nice video m8 keep it up

I needed this for my new gaming audio setup, not because of the inrush but because it makes a huge noise in the speaker.

As usual a great presentation & explanation 👍