@@ogasama6028 Those are the charger's line/input numbers. Usually lots of flexibility there. What matters most is the output that's going in to the device you're charging. Those numbers are important.
I am a college music professor looking to teach this subject in class and you explained it perfectly. I’ve been searching for an explanation like this for a long time. Thank you!
6:17 That "center negative" or "center positive" polarity diagram for barrel connectors was so helpful! I looked at the brick part of the adapter and it was right there! In plain sight!! Many thanks!
My wife brought home a Samsung Freestyle Projector… from her clients trash! (Worth about $300). It didn’t work but I noticed it had an 9v Apple charger with it. I bought the correct Samsung 20v charger and it works like a champ. Knowledge is power… or in this case.. money!
Well done. My Elmer who coached me for my general license presented voltage and amperage in virtually the same fashion. He has been a silent key for nearly 30 years but listening to you brought back my memories of him. It is odd that something so simple confuses so many people. I now find myself eager to watch more of your videos. 73's
Excellent. Only just seen this video. Very clearly explained, and best explanation I've seen. Can't understand why other videos have to complicate things.
Thank you do much for the refresher. It's been a while since my tinkering days of yore, and I needed to confirm a variable output on a buck box. Since W (P) is drawn, the equations imply that A (I) are drawn as well. But as my grandfather said, measure twice, cut once.
At the risk of confusing things further, it might help some people with an analogy to demystify what voltage and current (amps) are. The analogy isn't perfect, but helpful in some situations. The analogy is with water in pipes and hoses. Voltage is analogous to water pressure (PSI or Pascals). Current is analogous to flow of water (gallons per minute or liters per minute). The computer is analogous to an "appliance," such as a lawn sprinkler, that you attach to a faucet with a garden hose. And, the power supply is analogous to the faucet connected to the garden hose, limiting the flow of water (current) that goes to the sprinkler. That's why the water pressure (voltage) has to match what the lawn sprinkler can handle. If the water pressure is extremely high, then it might blow out the sprinkler, damaging it. If the water pressure is lower than the sprinkler is designed for, then the sprinkler doesn't operate correctly, dribbling water out and probably not rotating as designed. The results are similar if the flow of water supplied is less than what the sprinkler needs and is designed for.
Great information. Thank you. This is why RU-vid can be such a powerful learning aid, but it does not work without the support of professional like you.
I was on my computer and looking for an answer for this subject, you explained it simple and easy to understand that i had togot my phone to like, subscribe and comment on the video. Thank you soo much. 🙏
Sure you can use a charger with the same voltage and different amperage rating, it will charge at a different rate, but it will still charge. What is voltage, what is current? They actually go together, it might be what’s stamped on the device, but it’s the thing that is being charged that determines the current voltage relationship. You put a load on the battery and current will flow based upon the resistance within the device you are charging, but it’s the voltage that matters and determines how much current will flow. So as long as you don’t exceed the voltage rating for the device, only the current based upon the internal resistance will flow.
Also important is to plug the power supply into the device first and then into the wall outlet to avoid a surge that could damage your device. When your done unplug the power supply from the wall outlet and then unplug from the device being used.
I have to disagree with that. Power supplies, whether linear or switching contain reactive elements (coils and capacitors). When the power supply first turns on, those devices go through a transient period while they reach a steady state. It is during that transient period that anything bad could happen such as inductive voltage spikes that could potentially damage a device. Likewise, when the device loses power, it again goes from a steady state to a transient state while the reactive devices discharge. Once it has reached a steady state, it will regulate the voltage normally. The WORST that could happen while it is running steady state is that the device attempts to draw to much instantaneous power as might happen during the transient while the device is first plugged in. When that happens, the output capacitor buffering the voltage (present on any kind of related power supply) will be drained too quickly causing drop in voltage -- if the power supply isn't designed to be able to handle the power. A drop in voltage might disrupt the device for a moment; but, it will not damage the device the way that a voltage spike could. So in theory, to be as safe as possible, you should always plug the power supply in first and then plug the device into the power supply once it has reached steady state. Likewise, disconnect the device and then unplug the power supply so that it is not subject to any during shutdown transients. In reality, none of this should be important. A well engineered power supply should be designed to effectively filter the transients or to inhibit voltage output until the transients have subsided. That is why some higher power supplies with large active components may take take a few seconds to power on. When they do, you will hear the click of a relay enabling the power output. That relay is timed based on the length of time that the circuit transient needs to subside. So as long as you purchase power supplies from reputable brands, you shouldn't have any trouble. After all, what would happen during a power glitch? Your power supply and device would have to through power down and then power up transients. If you buy a cheap chinesium power supply from EBay, the engineers might not have spent enough time designing around the transients.
Jumble of B.S. I have been working in electronics for over 50 years. Worked on everything from radar, ICP, GCMS,ICPMS and have seen many devices powered by the beloved WALL WART destroyed by not proper plug in sequence. But this is what you can expect form a theory guy who has never worked in the real world. I guess I was not specific enough ! Have you ever seen a circuit board loaded with CMOS chips get destroyed by static electricity. Switching power supplies cannot handle transient spikes. It may be better now but in the 80s and 90s. We had to replace 5 power supplies in GCMS units because of power surge. Go online and see all of the power line conditioners on the market as well as C.V.T. units for 120, 220 and 440 volt three phase ! Equipment costing 100k or more with power supplies from CHINA that are amazing if the last 5 years !@@timharig
"Also important is to plug the power supply into the device first and then into the wall outlet to avoid a surge " Electrical engineer here. You have it exactly backwards. Plug it into the wall first.
Good tip on the polarity. Thanks for all this info. I admit that I only skimmed this video looking to answer my primary question, but am wondering if AC vs DC is discussed, sometimes I see "switching."
I just watched this video and would like to add that if you are reading the specs directly off the charger, make sure to take notice of whether it is rated AC or DC output. Make sure the charger and the device are the same type.
This was so helpful! I went through a bunch of videos but couldn't make it past rhe 5 minute mark. I just wanted ti know if i can use my laptop charger to charge my phone. Thank you 🙏🙏
Thanks, great explanation! clear & comprehensive. Question though, about 6:15 into your video you delve into polarity. What is the standard? center positive or negative & why would a vendor not use the standard, other than sheer hubris?
If it’s lithium ion that you are charging I thought it shortens the life of a battery the higher the amperage charger you use. I’ve had the notion that when charging a lithium battery the slower the charge the longer the overall life of the battery. Is any of this true. Thanks! I appreciate this video!
I make a lot of USB DIY for myself and I decided to measure polarity more than once and maybe test it with a disposable light thing and a not so important power bank. I can lose some, but the expensive device is sad to kill and it happens quickly.
Thank you sir i love you XD I had already ordered my device before i looked it up but my batter is 18/20 volts 6Amps and the device i bought is 12-24 volt 5 Amps The device is a Amplifier for a speaker system. Im going to make a diy speaker make uses a drill batter
If you are referring to a USB-x 5V powered device then the actual voltage from the power supply should be 5.1V-5.25V. That is to account for the voltage drop by the cord between the power supply and the device.
Hi Sir, kindly answer it My phone support 100W charging....i want to charge with slow charger..... in the original charger least 20W are mentioned and I'm using Apple original 20W charger. but the phone only Get 4W why? kindly explain
I have a question, please answer it - My mobile's charger output says 3 different values are: 5V 3A/9V 2A/12V 1.4A (it's a fast charger) and I have a smartwatch and earbuds both needs to be input of 5V 2A. Now the question is that can I use that charger to charge these devices or should I use 5V 2A charger only?
If Amps are 'drawn', should I assume Volts are 'pushed'? And if so, why the difference please? (The device draws what it needs, but the power supply is pushing its designated 'load'? Why does the device not draw the volts it also needs?
A voltage supply attempts to maintain a constant voltage. It does this by varying the current to maintain the voltage within its limits. A current supply attempts to maintain a constant current. It does this by varying the voltage within its limits. The vast majority of supplies that you are familiar with are voltage supplies.
I believe you are making some confusion with the terms here. Tha voltage refers to eletrical tension and is either 110V or 220V that comes out of the outlet. In this explanation, matches a 19 watts power supply with a 19 watts, watts not volts. Am I mistaken?
You are mistaken. ALL electricity has a measurement for both voltage and current. Power, measured in watts, equals voltage times current. Both sides of the power supply have a voltage across them and a current running through them. The input takes 110V or 220V. The input current will vary based on the load of the output. The output is 19V up to 1.58A of current. Assuming that the device uses the full 1.58A at the full 19V, it will be using 19V×1.58A = 30 watts. If we further assume that the input is 110V, then the input current being drawn would theoretically be 30W/110V = 0.27A. Realistically, the current will be a little higher do to conversion loss.
I charged a 12V hand drill battery with a 12v car battery charger and it went into meltdown...and ignition. I'm sure the explosion was coming. So was my new charger but I needed one fast charge in the mean time but I'm just putting this out there
idunno man, hand drill and a car work different by themselves, it may have worked at first, then something happened when you overdo it.. or maybe it the amps.
A car battery actually has a nominal charge of 12.6V. The alternator on your car generates 13V-14V. Some car battery chargers use more voltage than that for faster charging. Meanwhile, "20V" drill battery's are actually 18V generated from 5×3.6V lithium cells. The bottom line is that you a actually need to look at the actually voltage specifications four for device and not the device name.
@@timharig I had ordered the correct charger. It came in the post a few days after the catastrophe. I incidentally used a car battery charger to give a boost to a 14 volt drill battery but it didn't seem to overheat. The battery was possibly on the way out. Technology was advancing faster and 14volt stuff wasn't around long so I didn't care.
From the video said that: Voltage must be the same, little bit diferent maybe ok, a bit different voltage maybe still ok, but more different voltage can damage the device
USB is called 5V but the chargers are actually expected to output 5.1V to 5.25V to account for the voltage drop across the charging cable. As long as you have a GOOD adapter that supports enough current and a GOOD charging cable you should be fine. Cheap Chinese knockoffs may cause you trouble.
May i know about the watt? This is for my monitor adapter. I found something almost similar to original adapter but the original only 65w. And from the shop is 90w. Can you help me here? Thanks
Watt = volts x amps. The 90w adapter should work fine (so long as it provides the same voltage). The adapter provides power, the monitor consumes power. In order for the monitor to work correctly, the adapter must provide at least as much power as the monitor requires. A 90 w adaptor provides 90 watts. That is 25 watts more than the original adapter. It is important that the VOLTAGE of the replacement adapter be the same as the voltage of the original. If the original 65 watt adapter provided 24 volts, then it was rated at 2.7 amps (65/24 = 2.7). The replacement adapter should offer the same voltage as the original, 24 v in this example. A 90w adapter at 24v can therefore provide 3.75 a (90/24 = 3.75). As the video explains, this should be fine.
