This is great... Big Clive always says during teardowns of cheap equipment: "It's just a simple capacitive dropper"... thanks to your fuller explanation, I finally understand what that actually is.
"As you can see a switching power supply is too big for my tiny ATtiny85 project so I will make my own power supply from 3 ENORMOUS capacitors!" GreatScott's logic :D
He also put it in a rather big enclosure... Suming this all up: It doesn't make sense - only for educational purposes - but practically it saves zero space after all. Lmao
@@fusseldieb I think it is still true that these power supplies CAN be much smaller. From what I can tell, he was kind of just using parts he had, and he was also not trying to 'compactify' stuff, since spread out components are easier to see. I can definitely understand how this kind of power supply could be far smaller than the other, since you can pretty easily get very small capacitors that still have enough capacitance, but you can only get a transformer and some 10 other capacitors so small. Definitely though, the specific design should not be used for lightweight purposes XD.
Год назад
For 12mA, a 330nF capacitor, which is a lot smaller, will be enough. And a 1uF capacitor definitely will be. He also connected the LED wrong, a capacitive dropper only works with a full bridge rectifier or 2 LEDs. The circuit he build was a single diode rectifier with a capacitor.
@@TheCarpenterUnion Yep, I think zak is saying there's a maximum reverse voltage the LED can take and you need to be aware of that so as not to destroy the LED.
Great Scott: my group regularly builds supplies similar to this in the 60W range with a 98% efficiency. We have gone up to 500W for some applications. There should be a TVS on the front end and a MOV on the load side too.
it's not the inrush current that kills your LED's it's the reverse voltage needed to be dropped by the LED's. Inrush does kill your LED's though but much slower than that.
Ha! I was going to say that too about the reverse voltage. But as far as inrush, I don't think there is any in this circuit. Great idea by @Sean Smith to fix the circuit.
I learned about capacitive dropper circuits when I tried to add a timer to a heater. The PCB outputs 5V for some IC's, and I thought I could supply my Arduino with that. It surely worked without a hitch. The problem occured when I also connected the Arduino to my PC, because I was tired of disconnecting, checking on the heater if it works correctly, reconnecting, patching the software, etc. The moment I connected it, my breaker tripped, all capacitors on the arduino popped, the 5V line was toasted, and all my USB3 ports on the motherboard were dead. Luckily enough, the motherboard survived. I'd definitely recommend that motherboard for the durability. Will look up the model if anyone is interested. After closer inspection, i found out that the ground had continuity with the live/neutral wire. From that time on, I always check the power supply and conductivity before attempting any modification on cheap chinese appliances
Thank you for going over capacitive droppers and their dangers. They're VERY useful in small circuits but need to be handled with care. Using insulating rubber gloves is also a smart move.
2.2uF X2 class caps can be sourced cheap sometimes. I have made pretty much the same circuit as presented here quite a few times for several projects. The power can be a bit dirty (AC ripple) and is subject to RF interference. I remember having a CD4011 quad two input NAND gate configured as an SR latch operating off this capacitor power supply, and the latch would often false trigger. From memory the problem was solved with some hysteresis and further smoothing of the supply with some 104 caps. I exchanged the CD4011 with a CD4093 and used some 104 caps on the SR lines of the latch. ☆Great Scott☆ it worked! ... Think outside the □ and mix in some ♡ then use your ☆ for success... Gret video and thanx for sharing!
Hello Scott, I can recommend you "hi-link 5v" for powering your projects, it's super small, quite cheap and does it's work. Also it's enclosured. Of course it can be bought from our chinese friends :)
Love your clips .. I'm a 60yr old and have a passion to add electronics to my bucket list ...please make video clips for electronics for dummys like... myself. please
I've actually spent a lot of time messing with something similar in a circuit simulator and I had a lot more luck using an inductor as the reactance source rather than a capacitor. Putting a proper sized capacitor in parallel also greatly improves the power factor. That being said I also forwent the rectification and connected a pair of LED's with reversed bias directly in series with the reactor
When I was a kid, I _shocked_ to find that capacitive dropper actually, well, shocks. Still the worst shock I've ever gotten though. Unfortunately, the simplicity of this power supply comes at a cost. Besides its poor power factor and unisolated output, being an unregulated power supply, it's sensitive to load current, input voltage and even input waveform changes. Yes, you see that correct, even when the input isn't a perfect sine like for example, a modified sine wave from those cheap inverters, it really mess up the output of the power supply since it was calculated for a perfect sine and certain voltage and current range. Talking about inverter, one pro tip: don't use capacitive dropper based devices with modified sine wave inverter. It will result in overcurrent on the output of the power supply and possibly destroy anything connected on the output.
AC the most painful belt I've had was 115v 400hz on control stuff. DC was 267v (measured it after it bit me before I swapped the board) inside a radar. Burned a small hole in the skin on the knuckle.
Isn't this what the zener diode is meant to help with? To avoid the output voltage going high enough (within reason) and protecting the circuit from overvoltage damage?
Clamping zener is optional and some capacitive dropper circuit don't have clamping zener, mostly on things like, for example, LED lights and any device with internal rechargeable lead acid battery like flyswatter or emergency lights. These things aren't that sensitive to output changes on normal circumstances (slight input transient, etc) but definitely not designed for waveform changes. If I'm not mistaken, it's not about the RMS value. In fact, modified sine wave inverters do have around 220V RMS, with slightly lower peak voltage than sine wave for compensation. I believe it's about the formula. Different waveform requires different calculation, just like how you calculate RMS voltage from peak voltage with different waveforms.
@Great Scott - the first schematic and connections you showed almost certainly failed due to an LED's low reverse breakdown voltage typically WAY less than the PIV of mains. The simple inclusion of a reverse biased 1N4007 rectifier in parallel with the LED will solve that problem and a suitably specced inrush power resistor or better yet a suitable NTC in series with the input will solve (or massively reduce) the inrush current.
Hi Bob, did you mean a diode in series with the LED. This is how I used a 1n4005 diode in series with the LED to protect the LED from the high PIV that does kill the LED which was around 5 volts for the LED. However I was using g a resistor instead of a cap.
@@MegaVoltMeister no I didn't simply because with a capacitive dropper you need to allow the capacitor to both charge and discharge. With a resistive dropper you don't have that problem so EITHER will work, however the effective power dissipation in the resistor will increase (effectively double) if the rectifier is in parallel (full wave current through the resistor vs half wave). A resistor is fine with LOW AC volts, just as with DC volts, but the capacitive dropper is much more effective dissipation wise. Just beware the "bad" power factor.
but perhaps there is way to use cap and led circuit with mains AC , what will if i add diode parallel with led but opposite direction then led than that cap will enable to charge and #Discharge( reverse charge ) in both direction first via led then via diode so in such way led will survive from reverse cycle :) should be
This is a really good video! Editing and camerawork is clean and excellent. I like the diagrams you draw along with the explanations, they look really slick. And of course, the content is the best part; explained well and clear. Keep up the good work!
Most Chinese/HK power supplies deliver less than or equal to half of their rated current. If you see what looks like the same unit, same voltage and different current capacities in advertisements, then surely the real current capability is LESS than half of the advertised current capability and the voltage will sag greatly. Go ahead and test them! So your cost savings is likely to cost more than triple, after burning out and needing to buy a proper power supply that meets your current needs. It would make a great video and perhaps people will use this video as a reference design for your own home-designed and built power supply. ;)
Capacitive dropping circuits are in common use in everyday items. However, they are usually either hardwired, or use a plug that cannot be reversed (grounded, or in the U.S., polarized). A good example is a ceiling fan with multiple speeds. In a typical build, at 120 volts, the slow speed is obtained by using a 4.3uF capacitor, the medium speed is obtained by using a 2.1uF capacitor, and the high speed is obtained by direct connection (no capacitor). No other electronic components are used nor are multiple winding taps to the motor.
8:26 don't we need to subtract that zener voltage (5.1v) from that 233volts AC voltage and then divide it with calculated reactance to get our current value.
the 5.1 volts across the zener is negligible compared to the 233 volt mains. Do the calculations with and without it and you'll find only a couple of percent difference. The tolerance in the capacitor value is likely to be far greater than a few percent, so you're never going to get exact values anyway. This is the case in most electronic circuits, where components with tolerances of 5% - 20% are regularly used and in most applications this doesn't matter as long as the components are generously rated. It would be like using Google Maps to calculate the length of a car journey, then adding on 6 feet to allow for the length of your drive.
That was a really good presentation! I love the way you draw little graphs next to each stage of a circuit to illustrate what's happening at that point - that's a really good idea.
I think your first attempt of cap + LED only needed a diode across the LED to work. That allows the cap to charge on the “negative” AC cycles. The LED will not be subject to high voltage but will blink at 50 Hz
This was very educational for me. You must have been reluctant about doing a video about working with mains. Thank you for taking a chance and sharing your findings.
The REAL reason why your LED kept blowing up was the missing full bridge rectifier. Only in the first half of your AC wave your circuit was a voltage dropper, in the second half your LED is driven backwards. And in backward direction an LED basically acts like an open circuit, which means the entire 230 Volts are on the LED, until it blows.
Could be either/or. Plugin in near the top of the mains sine wave the empty cap is like a short and you have 230V spike at the LED. The direction does not matter in that case. But yeah, connecting LEDs to more than 5V (typical) reverse voltage is a no-no (and completely ignored in the video).
This was the tutorial topic I was looking for ages , on the whole YT there wasn't a single good enough video on this topic ; and you made this !! Thanks a lot Great Scott !
Years ago, when I was young, I tried powering a DC motor with one of the capacitive dropper circuit which I found inside an LED lamp. A few minutes later, I was able to witness the power resistor being converted into a smoking light bulb.
The tinkerning part is not isolated from mains power, thus landing this project in "High Voltage" land, the land where mistakes kill you. Yes, it is possible, but only for the very experienced.
Dear Scott: I have a suggestion: Instead of using a single capacitor in series with one side of the power line, why not put 2 capacitors of double capacitance value, one on each side of the power line? That way it doesn't matter which way the plug is plugged into the outlet. Also, if someone touches the output of the capacitor on the hot side, they will get a milder electric shock than they would if the circuit is made with just one capacitor, and some unlucky person plugs the plug in the outlet with the hot side being the non-capacitor side and touches the hot side. (Just a safety suggestion)
0:59 He needs to power the project through the AC outlet of his surge protector, yet there's a USB indicator for charging just below that socket. You do you...
I am your big fan from INDIA., Odisha...please dont ever try to collab with any other youtuber.... As you are one alone enough to teach all of us.... May God bless you.....
That was such a simple explanation of a very complicated formula and setup. I really feel I have a much better understanding of capacitive dropers now and feel I can start to use and implement them, I have a little easier time in the states at 110V ...lol..
Hi GreatScott! I am from India. Great work bro👏! Keep it up👍. I watch almost all of your videos. I really appreciate the quality and content of your videos. Thank you for giving us such premium content.
You can simplify the circuit and remove 1 of those diodes. You do it by changing two of the diodes in the bridge to be zeners. This removed the need for the extra zener.
Back in the 90's I had to work with a company to design a custom SMPS for a project I was leading. What I found was that you needed LV power to run the SMPS control and could not use the outpt of the supply because the controller was needed to created it. Sort of a chicken before the egg problem. What I found was that the SMPS needed a small direct-mains supply to get everything going. These supplies usually can't generate much power; but, if you don't need much power they are very simple and may suffice. I am sure the IC I used is long gone. It is certainly long forgot. I did a quick Google and found NPC785A. It accepts up to 450V DC in (provided by a simple rectified DC) and can produce 5V out, 10mA. Note: If you go 3-prong you could rectify to ground and reduce some of the safety issues (but no all) - certainly doing anything directly with AC Mains can be lethal.
Check always if capacitors are properly discharged. Also consider using an isolation transformer about 6VA for avoid single contact shocks , (but defeats eath) and less energy to blow up circuits
The trick that they get away in this remote controlled sockets, is to use a relay that uses higher voltage for the coil. Like 24 VDC here, this way you need less current and can do it with reasonable capacitors and zener diodes. Then drop it using linear regulator for the radio receiver circuit which uses very little.
Reminds me of my AC Fundamentals class. I still have nightmares from attempting to calculate values in Parallel RLC circuits. I still enjoyed watching your video and going over your calculations.
The reason the LED blew up was not (necessarily) the inrush current, but rather the reverse bias on the opposite half of the AC cycle. The minimal solution for not blowing up the LED is to either use a full bridge rectifier, or if you're ok with only lighting the LED for half the cycle, an antiparallel rectifier diode to clamp the voltage during the other half of the cycle. Inrush limiting would increase reliability of the circuit though.
Nice breakdown on capacitive droppers. My first introduction to them was a night light kit that I got online. It was only for 230 volt and, of course was very dim at 110 here in the US of A. So I played around and tried getting it working but ended up tossing the whole shebang in the bin. It did, however get me interested enough in this type of circuit to study and play around with them a bit. They can be useful in some instances, however I think I still prefer the old transformer with rectifier and filter method to obtain the DC voltages I need from the wall.
You should add a rectifier diode to protect the LED during the reverse half-cycle when powering it through a resistor direct from mains voltage. LEDs have a quite low breakdown voltage and will avalanche and get fried quite quickly. By the way, that is the way they did it for powering the light on an electric kettle I took apart.
My guess for the "secret" project: Home automation - A photodetector to monitor the light pulses from a smart meter and transmit the results over radio to a base station. Well, that's what I want to do, and was planning on using one of those SMPS modules, but this method could be a viable alternative if I can get the power requirements low enough.
You are amazing buddy. You give each and every step of making project. I am an engineering student and also try your projects at home. I require your little help. Would you please make a video on "Synchronization failure detection of power grid". It simply means if frequency or voltage of system goes below some specified value then an indication is given by an lamp. Please reply me if you'll make a video on this topic. Thank you
It's called a 'buck converter' and it can handle more than just a few milliamps. Using a non-polarized capacitor, such as a motor capacitor normally used with compressor motors, you can make a battery charger by connecting it to a rectifier. It's literally just those two components, and a cheap resistor over the output terminals to bleed off the capacitor when it is unplugged. When there is no load, the output terminals will be around the same as mains voltage...but when you connect it to a battery, the resistance of the battery causes the voltage to drop. The amount of current it can provide to charge the battery depends on the value of the capacitor. These types of chargers can resurrect a "dead" SLA battery because the output is still pulsing at the AC frequency of 60 Hz. The pulsing helps break apart certain kinds of crystallization that can form on the plates of battery cells. It can also charge other battery types quite well.
Didn't hear him mention it, but another reason to have the rectifier for an LED running of mains voltage in some form is to prevent the LED from avalanching when its reversed biased. You can get away with it with a resistor since its limited, but even cheapie Christmas lights usually have a rectifier in the plug to avoid stressing the LEDs (and reduce strobing).
Hi long time viewer first time request : please explain using a keypad as a wake up interrupt for arduino (promini) for use in a safe lock. i found some online resources but they seem quite complicated. your thorough style of teaching would help a lot thanks.
Watching this while wearing a "Full bridge rectifier" t-shirt from Electroboom and hearing Mehdi's voice when you pronounce it. Great video nonetheless, I like it that you did and explained the math for choosing the components.
Speaking of flipping the plug... Here in NZ we can't do that due to the prong design (earthed or otherwise)... great! But we screwed up (literally) with our bulb socket design where our bayonet (BC) bulbs can go in either way around; you never know where the live / neutral are. ES (Edison Screw) are a much more sensible design.
Great Scott : uses a mains voltage with a warning on the start
ElectroBOOM: holds 5k volts and no warnings
@@jkobain It still does hurt man^^
Because He is Mehdi Saghdar
So you can see what a capacitive dropper can't do😁😁😁
220v vs 110v
Because this fine Gentleman isn't stupid
Big difference between Greatscott and ElectroBoom
GreatScott: gives warning about 230V
ElectroBoom: Touches 2 Kv Transformer and just yelling around
rubber hand vs. hair hand :D
kV*
because in Iran human life is valueless
First you go home and touch 230 VAC then talk to GreatScott.
the warning is included within the show
This is great... Big Clive always says during teardowns of cheap equipment: "It's just a simple capacitive dropper"... thanks to your fuller explanation, I finally understand what that actually is.
I believe you pronounced "Full Bridge Rectifier" wrong.
It's supposed to be pronounced "FUUL BRIDGE REKTIFIAH", preferably with some kind of reverb.
فبقي
漢字
In Canukistan it's called a rectumfryer.
@@carpespasm In Germany it's a GLEICHRICHTER.
decay BRÜCKENGLEICHRICHTER
"As you can see a switching power supply is too big for my tiny ATtiny85 project so I will make my own power supply from 3 ENORMOUS capacitors!"
GreatScott's logic :D
He also put it in a rather big enclosure... Suming this all up: It doesn't make sense - only for educational purposes - but practically it saves zero space after all. Lmao
@@fusseldieb I think it is still true that these power supplies CAN be much smaller. From what I can tell, he was kind of just using parts he had, and he was also not trying to 'compactify' stuff, since spread out components are easier to see. I can definitely understand how this kind of power supply could be far smaller than the other, since you can pretty easily get very small capacitors that still have enough capacitance, but you can only get a transformer and some 10 other capacitors so small.
Definitely though, the specific design should not be used for lightweight purposes XD.
For 12mA, a 330nF capacitor, which is a lot smaller, will be enough. And a 1uF capacitor definitely will be. He also connected the LED wrong, a capacitive dropper only works with a full bridge rectifier or 2 LEDs. The circuit he build was a single diode rectifier with a capacitor.
I've watched so many of bigclive's videos that I can actually understand this video lol
Clive squad 🖖🏽
Yea!!
+1
Woot
It took me this video to get bigclives video :)
It would be interesting to see GreatScott and ElectroBOOM collab.... xD
Tell mehdi to tour Germany. He went to Japan lately so it would not be unreasonable to ask him to visit Germany...
@@sortsvane Good thinking :D
Greatscott : uses rubber gloves
Mehdi : sits on nichrome wire to roast his ass
how to blow up everything the most efficiant way
Ask him to sit on it..
When i first saw such a compact power supply in my home door bell, I was fascinated. Thanks for explaining the principles of the circuit.
@@jeffsadowski No. Modern mobile chargers are SMPS. They don't rely on capacitive reactance to drop out mains voltage.
@@jeffsadowski sure, if you like charging your 3,000mah battery with just 10ma /s
When you put the LED on main power, you need to take on concideration the reverse voltage on the LED with AC voltage.
It's a diode.
@@TheCarpenterUnion Yep, I think zak is saying there's a maximum reverse voltage the LED can take and you need to be aware of that so as not to destroy the LED.
@@TheCarpenterUnion Usually LED's have a maximum reverse voltage of 5V, anything more and you destroy the diode.
"jlcpcb sponsored this video" proceeds to create project just connecting pin to pin without using a single pcb...
Hush you.
because uses less WATs
To be fair, this garbage circuit doesn't deserve a pcb.
@@elijahvivio1996 it's a pretty useful garbage circuit tho
hahaha
soldering in mid air is a necessary skill. xD
Great Scott: my group regularly builds supplies similar to this in the 60W range with a 98% efficiency. We have gone up to 500W for some applications. There should be a TVS on the front end and a MOV on the load side too.
it's not the inrush current that kills your LED's it's the reverse voltage needed to be dropped by the LED's. Inrush does kill your LED's though but much slower than that.
To add to this, you can resolve the reverse current problem by adding another diode across the LED in the opposite direction.
@@rupert274 Wouldn't you have a bigger inrush current problem?
Why much slower? There was nothing limiting it
Ha! I was going to say that too about the reverse voltage. But as far as inrush, I don't think there is any in this circuit. Great idea by @Sean Smith to fix the circuit.
what i dont understand is why it worked with the resistor
7:19 english subtitles are the best
Electroboom confirmed on subtitles
Agreeeeeeeeee lol
True
I learned about capacitive dropper circuits when I tried to add a timer to a heater. The PCB outputs 5V for some IC's, and I thought I could supply my Arduino with that. It surely worked without a hitch. The problem occured when I also connected the Arduino to my PC, because I was tired of disconnecting, checking on the heater if it works correctly, reconnecting, patching the software, etc. The moment I connected it, my breaker tripped, all capacitors on the arduino popped, the 5V line was toasted, and all my USB3 ports on the motherboard were dead. Luckily enough, the motherboard survived. I'd definitely recommend that motherboard for the durability. Will look up the model if anyone is interested. After closer inspection, i found out that the ground had continuity with the live/neutral wire. From that time on, I always check the power supply and conductivity before attempting any modification on cheap chinese appliances
GreatScoot: this can kill you
ElectroBOOM: hold my beer
*SeAt WaRmEr*
Thank you for going over capacitive droppers and their dangers. They're VERY useful in small circuits but need to be handled with care. Using insulating rubber gloves is also a smart move.
5:53 FULL BRIDGE RECTIFIER
oh wrong Channel
FOOUUHHL BRIDGHZG REKHKHHTIFAAIEERRRR
do you know what is GreatScott channel ? 😆
BEAR HANDS 11:18
@@norman7535 BEAR HANDS... BEAR HANDS... WHAT'S UP WITH BEARS IN THIS LANGUAGE?! I FEEL SO BEARLY TODAY... BEEAR!
Sechspuls-Brückenschaltung or even fuller rectifier
2.2uF X2 class caps can be sourced cheap sometimes. I have made pretty much the same circuit as presented here quite a few times for several projects.
The power can be a bit dirty (AC ripple) and is subject to RF interference. I remember having a CD4011 quad two input NAND gate configured as an SR latch operating off this capacitor power supply, and the latch would often false trigger. From memory the problem was solved with some hysteresis and further smoothing of the supply with some 104 caps. I exchanged the CD4011 with a CD4093 and used some 104 caps on the SR lines of the latch. ☆Great Scott☆ it worked! ...
Think outside the □ and mix in some ♡ then use your ☆ for success...
Gret video and thanx for sharing!
Hello Scott,
I can recommend you "hi-link 5v" for powering your projects, it's super small, quite cheap and does it's work. Also it's enclosured. Of course it can be bought from our chinese friends :)
Love your clips ..
I'm a 60yr old and have a passion to add electronics to my bucket list ...please make video clips for electronics for dummys like...
myself.
please
I learned how to make capacitive droppers from Big Clive. They're great for making my own LED lightbulbs.
I've actually spent a lot of time messing with something similar in a circuit simulator and I had a lot more luck using an inductor as the reactance source rather than a capacitor. Putting a proper sized capacitor in parallel also greatly improves the power factor. That being said I also forwent the rectification and connected a pair of LED's with reversed bias directly in series with the reactor
Where is the video of this week?!!! I am going to cry 😥
I love how you explain everything and how precise and easy to read 6our schematics are!
When I was a kid, I _shocked_ to find that capacitive dropper actually, well, shocks. Still the worst shock I've ever gotten though.
Unfortunately, the simplicity of this power supply comes at a cost. Besides its poor power factor and unisolated output, being an unregulated power supply, it's sensitive to load current, input voltage and even input waveform changes. Yes, you see that correct, even when the input isn't a perfect sine like for example, a modified sine wave from those cheap inverters, it really mess up the output of the power supply since it was calculated for a perfect sine and certain voltage and current range. Talking about inverter, one pro tip: don't use capacitive dropper based devices with modified sine wave inverter. It will result in overcurrent on the output of the power supply and possibly destroy anything connected on the output.
I saw this circuit it in every cheap rechargable lead acid emergency lights.. and shocked myself many times while opened
AC the most painful belt I've had was 115v 400hz on control stuff.
DC was 267v (measured it after it bit me before I swapped the board) inside a radar. Burned a small hole in the skin on the knuckle.
Isn't this what the zener diode is meant to help with? To avoid the output voltage going high enough (within reason) and protecting the circuit from overvoltage damage?
Is that because it's not the same RMS value?
Clamping zener is optional and some capacitive dropper circuit don't have clamping zener, mostly on things like, for example, LED lights and any device with internal rechargeable lead acid battery like flyswatter or emergency lights. These things aren't that sensitive to output changes on normal circumstances (slight input transient, etc) but definitely not designed for waveform changes.
If I'm not mistaken, it's not about the RMS value. In fact, modified sine wave inverters do have around 220V RMS, with slightly lower peak voltage than sine wave for compensation. I believe it's about the formula. Different waveform requires different calculation, just like how you calculate RMS voltage from peak voltage with different waveforms.
Man your writing and symbol drawing is perfect
@Great Scott - the first schematic and connections you showed almost certainly failed due to an LED's low reverse breakdown voltage typically WAY less than the PIV of mains.
The simple inclusion of a reverse biased 1N4007 rectifier in parallel with the LED will solve that problem and a suitably specced inrush power resistor or better yet a suitable NTC in series with the input will solve (or massively reduce) the inrush current.
Hi Bob, did you mean a diode in series with the LED. This is how I used a 1n4005 diode in series with the LED to protect the LED from the high PIV that does kill the LED which was around 5 volts for the LED. However I was using g a resistor instead of a cap.
@@MegaVoltMeister no I didn't simply because with a capacitive dropper you need to allow the capacitor to both charge and discharge. With a resistive dropper you don't have that problem so EITHER will work, however the effective power dissipation in the resistor will increase (effectively double) if the rectifier is in parallel (full wave current through the resistor vs half wave). A resistor is fine with LOW AC volts, just as with DC volts, but the capacitive dropper is much more effective dissipation wise. Just beware the "bad" power factor.
yes there should be diode to block reverse current from AC second cycle or rev voltage .
but this is case for rasistor
but perhaps there is way to use cap and led circuit with mains AC , what will if i add diode parallel with led but opposite direction then led than that cap will enable to charge and #Discharge( reverse charge ) in both direction first via led then via diode so in such way led will survive from reverse cycle :) should be
world philosophy can't use electronic technology without full bridgeeeee rectifierrrrrr @electroboom & @greatscott 2020 😂❤️🇮🇷
Great Scott: Advertises JLCPCB.
Also Great Scott: Builds dangerous circuit without any insulation hoping gravity won't burn his house down.
I usually don't understand your video (I'm a beginner I did not study it) but I guess I understood nearly everything in this one! Thanks!
Dangerous, you said? I'm definitely making this one.
OMG TheSmkngun, wear a face shield 😳
This is a really good video! Editing and camerawork is clean and excellent. I like the diagrams you draw along with the explanations, they look really slick. And of course, the content is the best part; explained well and clear. Keep up the good work!
Greatscott:This is very dangerous
ElectroBOOM:hold my wire
I have exactly the same issue, and this is why I ordered from China the HLK-PM01 switched mini power supply module, around 3 EUR
Most Chinese/HK power supplies deliver less than or equal to half of their rated current. If you see what looks like the same unit, same voltage and different current capacities in advertisements, then surely the real current capability is LESS than half of the advertised current capability and the voltage will sag greatly. Go ahead and test them! So your cost savings is likely to cost more than triple, after burning out and needing to buy a proper power supply that meets your current needs. It would make a great video and perhaps people will use this video as a reference design for your own home-designed and built power supply. ;)
Next time please pronounce *FHUUL BRIADGE RHECKTHIFIA* right with some reverb
Capacitive dropping circuits are in common use in everyday items. However, they are usually either hardwired, or use a plug that cannot be reversed (grounded, or in the U.S., polarized). A good example is a ceiling fan with multiple speeds. In a typical build, at 120 volts, the slow speed is obtained by using a 4.3uF capacitor, the medium speed is obtained by using a 2.1uF capacitor, and the high speed is obtained by direct connection (no capacitor). No other electronic components are used nor are multiple winding taps to the motor.
8:26 don't we need to subtract that zener voltage (5.1v) from that 233volts AC voltage and then divide it with calculated reactance to get our current value.
the 5.1 volts across the zener is negligible compared to the 233 volt mains. Do the calculations with and without it and you'll find only a couple of percent difference. The tolerance in the capacitor value is likely to be far greater than a few percent, so you're never going to get exact values anyway. This is the case in most electronic circuits, where components with tolerances of 5% - 20% are regularly used and in most applications this doesn't matter as long as the components are generously rated.
It would be like using Google Maps to calculate the length of a car journey, then adding on 6 feet to allow for the length of your drive.
For most of my circuits/projects that require mains to
0:29 the last time I try to sold an energized component, he blowup in my face... :D
Solder*
That was a really good presentation!
I love the way you draw little graphs next to each stage of a circuit to illustrate what's happening at that point - that's a really good idea.
10:47 note: should read "inside a closed, non-conductive housing". I would even be tempted to goop the whole circuit
If the housing is grounded the breaker will trip if there is a short.
I think your first attempt of cap + LED only needed a diode across the LED to work. That allows the cap to charge on the “negative” AC cycles.
The LED will not be subject to high voltage but will blink at 50 Hz
This is correct, he got 600v reverse voltage on the LED in the negative cycle.
hi sir i like your videos im from india im also a youtuber
love from india
@Dio Brando pewrandi
This was very educational for me. You must have been reluctant about doing a video about working with mains. Thank you for taking a chance and sharing your findings.
The REAL reason why your LED kept blowing up was the missing full bridge rectifier. Only in the first half of your AC wave your circuit was a voltage dropper, in the second half your LED is driven backwards. And in backward direction an LED basically acts like an open circuit, which means the entire 230 Volts are on the LED, until it blows.
Could be either/or. Plugin in near the top of the mains sine wave the empty cap is like a short and you have 230V spike at the LED. The direction does not matter in that case. But yeah, connecting LEDs to more than 5V (typical) reverse voltage is a no-no (and completely ignored in the video).
This was the tutorial topic I was looking for ages , on the whole YT there wasn't a single good enough video on this topic ; and you made this !! Thanks a lot Great Scott !
Beter end the video with: "Stay alive, and we may see you next time!"
You made me laugh 😀
bestest ever video on capacitive dropper circuit.
Could you please make a video on how to build a SMPS and the concepts it requires.
Maybe one day.....not sure.
Thanks for walking through this, it helped quite a bit.
*FULL BRIDGE RECTIFIER*
why i hear Mehdi voice
Some may hear it as a Full Bridge Rektumfryer.. hee-hee
This is the only circuit of yours that I have clearly understood
Dangerous and it doesn’t supply much power on the output?
Wow, count me in!
His hand writing is so perfect.
Make a video on vacuum fluorescent displays!
Years ago, when I was young, I tried powering a DC motor with one of the capacitive dropper circuit which I found inside an LED lamp. A few minutes later, I was able to witness the power resistor being converted into a smoking light bulb.
6:01
but why? these circuits meant to be as cheap as possible while being very operational and optimal. whats the problem?
The risk of electric shock+fire.
The tinkerning part is not isolated from mains power, thus landing this project in "High Voltage" land, the land where mistakes kill you. Yes, it is possible, but only for the very experienced.
Dear Scott: I have a suggestion: Instead of using a single capacitor in series with one side of the power line, why not put 2 capacitors of double capacitance value, one on each side of the power line? That way it doesn't matter which way the plug is plugged into the outlet. Also, if someone touches the output of the capacitor on the hot side, they will get a milder electric shock than they would if the circuit is made with just one capacitor, and some unlucky person plugs the plug in the outlet with the hot side being the non-capacitor side and touches the hot side. (Just a safety suggestion)
the scariest thing about this is his unique wire-tangle prototyping method... what's wrong with a breadboard?
6:07
Electroboom needs that for all the times he plugs something in and it explodes in his face.
0:59 He needs to power the project through the AC outlet of his surge protector, yet there's a USB indicator for charging just below that socket. You do you...
You are very good teacher. You method of explaination is very intuitive.
I always wait for your awesome video.
Thanks
FULL BRIDGE RECTIFIER
*ElectroBOOM wants to know your location*
He knows him, in germany
I am your big fan from INDIA., Odisha...please dont ever try to collab with any other youtuber.... As you are one alone enough to teach all of us.... May God bless you.....
I am researching to build one, and you come to my rescue.
That was such a simple explanation of a very complicated formula and setup. I really feel I have a much better understanding of capacitive dropers now and feel I can start to use and implement them, I have a little easier time in the states at 110V ...lol..
Superb video, finally understand capacitive droppers!
A big love from India to great scott
Hi GreatScott! I am from India.
Great work bro👏! Keep it up👍.
I watch almost all of your videos. I really appreciate the quality and content of your videos.
Thank you for giving us such premium content.
You can simplify the circuit and remove 1 of those diodes. You do it by changing two of the diodes in the bridge to be zeners. This removed the need for the extra zener.
What a perfect timing! I was looking for a tutorial on this topic
Back in the 90's I had to work with a company to design a custom SMPS for a project I was leading. What I found was that you needed LV power to run the SMPS control and could not use the outpt of the supply because the controller was needed to created it. Sort of a chicken before the egg problem. What I found was that the SMPS needed a small direct-mains supply to get everything going. These supplies usually can't generate much power; but, if you don't need much power they are very simple and may suffice. I am sure the IC I used is long gone. It is certainly long forgot. I did a quick Google and found NPC785A. It accepts up to 450V DC in (provided by a simple rectified DC) and can produce 5V out, 10mA. Note: If you go 3-prong you could rectify to ground and reduce some of the safety issues (but no all) - certainly doing anything directly with AC Mains can be lethal.
This kind of supply is used in many small devices, like Teckin SP22 smart plug. Very interesting and dangerous. Congrats.
Love your schematics and calculations.
You taught me more things than my electronic school... Thanks
Bigclive has many videos about this kind of power suply. You can't go wrong watching his videos.
Exhausted my today's internet, totally fucked up, first thing to do to watch your video at 00:00 (GMT+5:30) When my datapack renews. 🙄😁😁😂
Thanks for the explanation of the rubber gloves
Check always if capacitors are properly discharged. Also consider using an isolation transformer about 6VA for avoid single contact shocks , (but defeats eath) and less energy to blow up circuits
Outstandingly informative and concise.
The trick that they get away in this remote controlled sockets, is to use a relay that uses higher voltage for the coil. Like 24 VDC here, this way you need less current and can do it with reasonable capacitors and zener diodes. Then drop it using linear regulator for the radio receiver circuit which uses very little.
Reminds me of my AC Fundamentals class. I still have nightmares from attempting to calculate values in Parallel RLC circuits. I still enjoyed watching your video and going over your calculations.
One can use inductance coil, to limit the current during capacitor charging. That could save your LED when you plug in the socket
The reason the LED blew up was not (necessarily) the inrush current, but rather the reverse bias on the opposite half of the AC cycle. The minimal solution for not blowing up the LED is to either use a full bridge rectifier, or if you're ok with only lighting the LED for half the cycle, an antiparallel rectifier diode to clamp the voltage during the other half of the cycle. Inrush limiting would increase reliability of the circuit though.
GreatScott:
Electroboom: BOOOM!! 💥
Nice breakdown on capacitive droppers. My first introduction to them was a night light kit that I got online. It was only for 230 volt and, of course was very dim at 110 here in the US of A. So I played around and tried getting it working but ended up tossing the whole shebang in the bin. It did, however get me interested enough in this type of circuit to study and play around with them a bit. They can be useful in some instances, however I think I still prefer the old transformer with rectifier and filter method to obtain the DC voltages I need from the wall.
You should add a rectifier diode to protect the LED during the reverse half-cycle when powering it through a resistor direct from mains voltage. LEDs have a quite low breakdown voltage and will avalanche and get fried quite quickly. By the way, that is the way they did it for powering the light on an electric kettle I took apart.
My guess for the "secret" project: Home automation - A photodetector to monitor the light pulses from a smart meter and transmit the results over radio to a base station.
Well, that's what I want to do, and was planning on using one of those SMPS modules, but this method could be a viable alternative if I can get the power requirements low enough.
You are amazing buddy. You give each and every step of making project. I am an engineering student and also try your projects at home. I require your little help. Would you please make a video on "Synchronization failure detection of power grid". It simply means if frequency or voltage of system goes below some specified value then an indication is given by an lamp. Please reply me if you'll make a video on this topic. Thank you
It's called a 'buck converter' and it can handle more than just a few milliamps. Using a non-polarized capacitor, such as a motor capacitor normally used with compressor motors, you can make a battery charger by connecting it to a rectifier. It's literally just those two components, and a cheap resistor over the output terminals to bleed off the capacitor when it is unplugged. When there is no load, the output terminals will be around the same as mains voltage...but when you connect it to a battery, the resistance of the battery causes the voltage to drop. The amount of current it can provide to charge the battery depends on the value of the capacitor. These types of chargers can resurrect a "dead" SLA battery because the output is still pulsing at the AC frequency of 60 Hz. The pulsing helps break apart certain kinds of crystallization that can form on the plates of battery cells. It can also charge other battery types quite well.
Good explanation thanks
Didn't hear him mention it, but another reason to have the rectifier for an LED running of mains voltage in some form is to prevent the LED from avalanching when its reversed biased. You can get away with it with a resistor since its limited, but even cheapie Christmas lights usually have a rectifier in the plug to avoid stressing the LEDs (and reduce strobing).
Hi long time viewer first time request : please explain using a keypad as a wake up interrupt for arduino (promini) for use in a safe lock. i found some online resources but they seem quite complicated. your thorough style of teaching would help a lot thanks.
As your circuit uses a bridge rectifier, the output voltage will be reference to 1/2 mains supply whichever way the plug is inserted.
Great Scott, can you please make a video on air ionizers found in some fans? How do they work? Are they safe?
Great Scott you are great as name , many doubt clear after seen this video
Watching this while wearing a "Full bridge rectifier" t-shirt from Electroboom and hearing Mehdi's voice when you pronounce it. Great video nonetheless, I like it that you did and explained the math for choosing the components.
For lighting up few led we don't need complex components only resistors of appropriate value is sufficient. We see in indicators.
Excellent job well even your schematic diagrams were A + i can use this in my projects
Speaking of flipping the plug... Here in NZ we can't do that due to the prong design (earthed or otherwise)... great!
But we screwed up (literally) with our bulb socket design where our bayonet (BC) bulbs can go in either way around; you never know where the live / neutral are. ES (Edison Screw) are a much more sensible design.