Exactly and since ebikes are popular, batteries for ebikes become cheap so we can use them for projects. We built a remote operated vehicle that runs on a 48v ebike battery at work.
I found the title misleading. It's not a power "supply" really. It's a smart DC to DC voltage and current regulator. You still have to spend the big bucks on getting your mains rectified, isolated and dropped down. I suppose you could hook it up to batteries or solar cells, but it's still not the 'supply'.
AND you need a Dam to power the power station that powers the power supply that powers the power supply. Don't worry, there will be enough left for your light bulb and hot plate. Your power meter may saw a slot through your house, though. ;-)
If you really need a basic power supply you could jury rig a enclosed circuit board that plugs into the wall goes into a full wave rectifier and a couple filter caps. Probably those caps need to be rated 220v and I guess everything would be going through the rectifier. So you need a beefy rectifier. Max 1500 w from the wall ?
I am a radio enthusiast who monitors VHF and shortwave bands. I have very mixed feelings on some these cheap, sometimes questionable build quality switch-mode transformers used in increasing numbers in modern electronics which are unfortunately known for strong excessive RFI (radio frequency interference) My LED computer monitor which likely uses a cheap 19 volt switch mode power adapter emits widespread interference throughout the entire shortwave band likely becoming a major issue if your a Ham radio operator or receive only listener. I do have a new somewhat pricy TekPower 30 amp swiching power supply I use with my CB radio and other low or high amp 12 volt gadgets. This supply specifically designed 2 way radio use also emits some RFI but does have a nifty noise offset to tune out any self made noises it generates, but cheap poorly designed power supplies are a growing issue to radio enthusiasts.
There isn't a great deal you can do about all the junk that the neighbours have plugged in, but if you're doing anything with audio, including radio, the better bet is have a decent linear supply. Linear supplies are generally larger, heavier, far less efficient, more expensive to buy and more expensive to post. You're not paying this price for nothing though - All these characteristics are the price you pay for very low noise output. I have pulled the supplies out of my monitors and replaced them with a linear regulator setting the reference for a series pass transistor stage on a sheet of 1/4inch thick aluminium. It runs screaming hot, but it adds nothing to the noise floor from audio up to 440Mhz (my playground). It IS possible to get SMPS that are very very low noise, and when I'm rich and famous, I'll go to the effort of stress testing a few. Until then, I dump money, in the form of heat, into reliable and low noise linear tech.
@David Daivdson I am genuinely surprised that the national regulators tolerate it. The place it is most noticeable is HF (3 - 30MHz). Yes, for amateurs it is really really annoying, but they're not the only group of people affected by this. The military of any developed nation still uses HF for long range communications that can operate "off grid". No repeaters, no satellites, no phone lines. I can't believe that in an age where police are empowered to kick down doors over mean tweets, they allow critical infrastructure to be jammed by joke electronics.
@@digitalradiohacker I suspect that the benefit of higher power supply efficiency outweighs the higher noise floor for ham operators. Very few people use ham radios anymore anyway, at least here in the UK.
This has been a problem for a long time now, but the only thing that you can do about it is drive out to a mountain top that is at least 3 miles from any civilization, then set up your HF radio gear and then drive your car a 1/4 mile away from your radio antenna or remove the battery cable so that the ECU computer shuts down all the way. Unless you have an old vehicle, pre computer era or at least OBD 1 not 2 let's face it there's more switched mode power supply's out there than you can ever imagine, all new appliances, refrigerators, washers and dryers, stoves, and then there is lights it got really bad at night because of CFL lamps (compact fluorescent lamps). But fortunately those are going away slowly, and bring replaced by LED's which still produce some noise, but not nearly as much as the CFL lamps do. The CFL lamps are bad because of the high voltage required to ionize the gas in the lamp. But TV'S and computers are horrible offenders as they have both a switching power supply, and extremely fast processors. But in addition to those there's little things like chargers for Electric razors, and Electric toothbrushes, and then medical devices such as CPAP machines, there are 2 of those in my house, and they both have those inline power brick power supply's like a laptop computer, and they're all generating noise some a little some a lot. Strangely enough one of the worst offenders I have ever come across is one of those little switcher buck converters that plugs into the cigarette lighter or auxiliary power jack in your car, and it was a really nice one triple output 4.6 amp unit. I didn't realize it was the problem at first but I was sometimes having trouble receiving my favorite Christan radio station, and not AM but FM, and a local station at that. And it seemed to be random, it would be there and then suddenly disappear. Well one day I had gone somewhere a short distance from home, I was not in my truck but a few minutes, and when I went to get out, for some reason I unplugged my phone before turning off the truck radio and most of the interference instantly disappeared so I pulled that buck conver out of the auxiliary power jack, and all the interference instantly disappeared, and I had a full quieting signal. So yes some of those things are noisy all the way up into at least the VHF band's and maybe even further. One of these days I will have a look at it with a spectrum analyzer, and just see where all it is visibly trashing the spectrum.
I was under the impression the anglo sphere does not use U to designate voltage variables, but V? (which woul dbe confusing because the unit is also V, but hey, that's what it seemed to me so far)
Nope, that's an IRF something meaning that it's more likely to be a MOSFET. However, they might be measuring temperature using that one. A bit overkill and unnecessary but who knows, Chinese wisdom maybe?
The erase of the part numbers on the chip, the markings look interesting, could it be done with a pulsed laser beam? Looks like little dots with some tiny overlapping.
Ah! This must be it! I was puzzling over how the hell they could make a quick and easily-automatable scrubbing method that would end up looking like that.
They probably use a galvo steered beam from something like a fiber laser. Set up a fixture to register the board, program the size and location of the chips and fire away.Beats getting out a dremel.
Yes, that is laser engraving. There are many reasons to obscure the components. The devices are not designed to be serviced, so there is not a huge impact for consumers.
Higher voltages are useful for high end bldc motors and servos, they typically have flatter torque curves at higher voltages. 96v would come in handy as a cheap supply for anodizing titanium as well. I'll watch the rest of the video before I decide to I need to pick one of these up!
It is a but unfortunate that these (and other similar) "power supplies" really are just DC-DC converters. To have a lab power supply, it would be favorable when they had a 230V AC input and isolation. I know I can order a separate fixed switchmode supply for 60V or similar but that kind of defeats the purpose of having a cheap lab power supply. Hopefully one time they bring out boxes with AC input (and of course with the required safety).
I use my dps5015 (50V at 15A) Power by my old arc welder transformer and a smaller transformer to drop the primary voltage to the main transformer. But the transformer from the welder has no built in magnetic shunt, so baisicly a normal transformer just a huge ~1500W one.
Yeah, it'd be great to use the ready supply of AC at these power levels. You're not going to find an old laptop/pc power supply putting out 2kW. Maybe rip the transformer out of a microwave, but then you're getting sketchy as. For a "lab" power supply I'd rather something that's reliable, linear and self-contained. But I rarely need >100W
@@MrSnoots you probably dont want to do this. those transformers are designed to be "lossy" and you have to hack in somehow a new secondary. finding a transformer which does 2KW can be a tricky task. but im still not fully convinced that it can handle the 2 kW anyway. maybe more 2 chinese kW
You can tell it is Chinese whenever there is a"technical parameters", seems like nobody can get this translate to the more common technical specifications
Dave, please, test these two devices for max load. I understand that won't be easy, but possible. At least you can connect a number of your PSUs outputs in series to achieve higher voltage to supply DUT, then load it with some ballast resistor (nichrome wire wound). Thanks.
Mikeselectricstuff did a “dummy load in a bucket” video some time ago. I really want to see if these things can handle what they claim or if they explode/catch fire!
Makes you wonder when a 105V input supply has a 100V rated capacitor across it/s input. I know they survive modest overload but that's not good practice surely?
The weirdness you were having seems like it could be from the voltage drop across your input wires. The voltage that ends up at the input is likely less than the minimum input voltage of 20V. How about re-doing some of your tests, but feeding it say 30V or more from your supply?
For testing higher loads, you could use a string of SLA batteries in series for the DC input supply, plenty of current on tap. Just 4 of them from a typical UPS will give you 48V.
That top to bottom Via stitching is probably significantly helping reduce the resistive losses, because the vias are filled with solder and hence can carry current laterally ie across their diameter! So instead of the current just flowing through the top and bottom layer copper, it can also flow inplane across each via, and as the via's are very close together, they will act as a reasonable, "conductor" of some equivalent thickness to the pcb itself (1.6mm) rather than just the thicknesses of the top and bottom traces (~ 0.07mm for 2x 1Oz layers)
Dave, pretty please with ice cream, cherries and frosting on top; Give it the beans, FULL POWAAAA! This would be perfect for a parralel resonance induction heating project for small parts I'm working on. It would be absolutely perfect if it works but as cheap as it is, it's still a good bit of money in the current climate (cough!) and I'd hate to be waiting around for 40 days (the stated max delivery time) only to find out it doesn't work. -Charlie, a fan on the other side of the of the boarder lock down
Last year I had the big luck to get a new, original packed Cisco Systems PWR-C45-2800ACV Catalyst 4500 2800W AC Power Supply for less than 50 € (2800W +3,3V/12,1A, -50V/28A, +12V/113,3A) It is a power monster. It has no on/off switch but there are how to´s in the net.
Dave becomes lazy, he had all the equipment to test dropout voltage. Two minute test. I liked his videos for their entertainment _and_ educational value. That last point gradually diminishes. Then what, unboxing videos? Yes, I'm a little grumpy now. :)
16:02 - almost looks like laser pulses were used to erase the chip faces. would make sense as it would be a rapid process to erase an entire board in a few seconds.
Hi guys, I just bought this device: the DPM8608-RF I was wondering if you other owners have the same problems like me: When turning on the device, the output is always short-circuited for a few seconds, during the boot-process (when the fan runs for a few seconds). With the "Fast-speed discharging" function enabled, the output is short-circuited in the idle state (output off) continually. This does not happen when the "Fast-speed discharging" function is disabled. Only when the output is switched on (press OK), the output gives power like you would expect and there is no short circuit of course. In both cases the charger is supplied by an external power supply and is switched on. Secondly there are extremely high inrush currents on the input and output.It happens when connecting the charger to a power supply in the input side, when the power-switch is in the on-state. Also the device reboots every 2 seconds when the power supply is connected from a powerless state, and the power-switch was already in the on-state.It also happens when connecting a battery to the output. Please watch my videos, by clicking on the following links: 1. "Fast-speed discharging" function enabled: photos.app.goo.gl/2Rjre5GXnTh81FZY8 You see a 18650 battery connected to the output of the device. I connected a little motor as a reference to visualize the short-circuit. When I turn on the device in de idle-state (no power on output), you see the motor turning, because it is fed by the battery in the closed loop. This is because the output is short-circuited. 2. "Fast-speed discharging" function disabled: photos.app.goo.gl/caLsksMpYfHZzR2r6 When powering on the deice, the motor is running for a few seconds and is fed by the battery in the closed loop. Again, this is because the output is short-circuited.
32:32 I've tried on multiple occasions and have been unable to find cheap knobs without markers (mainly for use with rotary encoders) on eBay or aliexpress.
My first test for a power supply with maximum rated output voltage above 12V is to take it *straight* out of the box, take my #4 jumper wires with banana plugs or fork terminals (got both), and use those to hook up the output to my car’s battery. If some magic smoke escapes or if it doesn’t power up after that - I put it nicely right back in the box and ship it back. There were a couple HP supplies a while ago that didn’t pass that test, sadly. Can’t remember the model, sorry. This may sound like an arbitrary test but I really had very few problems with the models that were immune to being back driven from a source with a couple hundred amps of short circuit current capacity. It was my Hogwarts sorting hat for power supplies.
Impressive, particularly with that wifi toggle box included but I reckon an AC to DC converter that could play along at those power-altitudes, would take it to a completely another price ballpark.
The problem with all of these switching power modules is that they don't convert from the AC line, but require a high power DC input. Without a converter from the line they are useless as a bench supply.
Yeah, I can't think of any path to an isolated DC supply of that magnitude that doesn't at least double the cost. Even something like a few car batteries or used server power supplies in series add up. Still probably a screaming deal, but you have to keep in mind the price of a usable assembly here, not just the core component.
You can send one of them to me in the states and I'll put it thru its paces. I have 2 higher power capable supplies, one 60V/50A @ 2500W max. and one 20v/115A 2800W max., both running off 240vac single phase. The 2500W is rated for 3KW but only when running off 3-phase power. I have a Transistor Devices electronic load that will do 600V/400A @ 4000W! You can pick up 48v server supplies off Fleabay relatively inexpensively which would be a great way of powering one of these supplies (regulators).
I have the opposite problem. I own a 20.5 + 20.5 Vac 30 +30 amp iron core transformer and all the filtering capacitors and rectifiers... A linear regulator would be an insane waste of power!
@@EEVblog I guess it's like that for aluminium. With titanium you get colours with the oxide layer on it's own and the higher voltages colours are more resistant to fingerprints and skin oils, so thats what I use. Just google "titanium colour chart" if you are interested.
I've seen scratched out chips on other Chinese electronics, I believe they do it so other companies can't steal their design and make a even cheaper knock off. It's a theory of course but since they do it on all products regardless of price level I think it does hold some water.
I suspect that on these super low price items the scratcing might be to conceal that the chips are actually name brand chips that failed QC and were meant to be destroyed, but which the Chinese manufacturer sold off cheaply (and illegally or at least gray zone) to make a few extra bucks.
I do not understand why/how caps on the output can dump anything when the supply shuts down. That big cap will already be at output potential and will only be able to hold up the rail for a small time (and wreck-up its step response). There would need to be something that is storing energy at a higher potential that gets released after the regulation circuit shuts off. Perhaps the input cap gets suddenly connected to the output due to improper FET failsafe? I have seen it before where a micro controller brownout caused all the I/Os to change to default tri-state and that caused connected circuit to misbehave... badly.
If you need to control a lot of current it's a good value. Non-isolated design isn't critical since the power supply that is running it should take care of the mains isolation.
Not trying to sound negative, but isn't it a bit misleading to call a buck converter a "power supply"? It's sorta like calling your car's transmission the engine.
A "power supply" at a bare minimum is one that lets you program the output voltage. A "Lab power supply" lets you set the voltage and current. This supply does both, so it's *clearly* a "power supply". Just because it uses a buck topology is entirely inconsequential. In every linear lab power supply on the market is essentially a "buck", because it reduces and regulates the voltage.
@@EEVblog Don't you have to HAVE the voltage first? i have been looking for inexpensive 48 volt DC power supplies with 25 to 90 amp outputs for a few years now and they are pretty hard to find. And---- your title didn't say "Lab" Also, just for the sake of discussion, I'd say that "bare minimum" (YOUR term) should start with the Power not the controls. I don't have to win this exchange. I just wanted to give you my not quite novice opinion as a fairly regular viewer.
@@EEVblog - and Dave misses the point completely! This device doesn't take MAINS AC power and convert it to DC - it requires an additional *power supply* to operate! At 17:45 you show the separate *power supply* that you used to test it with.
Maybe i'm wrong but you interpret the input voltage spec as a requirement to be able to achieve the output voltage. I interpret that as the maximum voltage the psu can take. I don't think you can use those ratings to determine the voltage drop the psu will generate
over here in the USofA you could probably get away with using a decently large auto-transformer to drop the mains and rectify it to get ~110VDC... only issue would be input/output would be mains referenced and not isolated in any way
You can use a transformer n rectifier set up from a treadmill. They use 130v dc motors. That could easily supply any of these the mains ac/dc power at decent amperage.
Server "common slot" power supplies can be wired in series/parallel to create massive DC supplies. Check e Bay for a DPS-800. For around 20 bucks used, it'll put out 1kW with a 240VAC input and 12V at 83A output. They do current sharing so you can parallel them to make high current supplies. Open the power supplies up and by using fiber washers and/or nylon screws you can isolate the supplies so that they can be wired in series. I've got six and by using the mating "hot plug" connectors (salvaged from some HP server backplanes), I can put them in one config for a 6kW 12V 500A supply (for testing car inverters), or I can put them in series as a 72V 83A supply to power a DeWalt 60V chainsaw. (I have it fused at 30A and wired with 10AWG SOOW wire but it's ice if I need to do alot of cutting.) Oh yeah, they are NOT quiet but what do you expect for a server power supply?
I use 2 or these server supplies in series for a 25 Vdc 83 A source for my various buck/boost converters for bulk charging and testing. Bought mine for $15 each delivered, then did the magic with the pins to make them isolated. Nice 2000 watt supply 😃
First of all, the VIAs distribute heat so all the heat can be transfered to the side with the better cooling. The VIA Stitching is actually called "Cheese holeing". First of all, the holes reduce the inductivity of the trace which is not only neat for RF (Processors) but also comes in handy for high currents. Also it prevents "current strings" where all the current tries to narrow down in a tight path creating an immense current density and melting spots of the trace. With all the vias, the current is distributed more evenly over the width of the trace.
Hi, there is fw updates for DL3021 series, overshort problems etc... We had problems one test device at DL3021 overshorting. Rigol send whole new unit and it was B revision.
It's weird seeing wattages that sound too high to be legal. In NZ, you'd need to plug this into your electric stove to get 3kw @18 amps, as our wall sockets are at 10 amps max! Where I live the 1945 transformer puts out ac at 239 to 242 volts depending on time of day.
41:31 Look at how the inductor windings are almost shorted together! The long un-enameled leads are almost on top of eachother! Yikes! Just a small jiggle in shipping and you might get a dud. I noticed that the inductor in the smaller unit had the same issue, but not nearly as bad.
That’s what I was thinking! My last TV died and I had no easy way to check if the backlight was working because it was like 75 volts or something. However, this is the only time I can think of where a 60-96V supply would have been handy for me
This looks like exactly the kind of thing I was thinking I might have to design from scratch, for charging a 48V battery bank with current limiting depending how much power is available from a Solar inverter, so I can be sure not to take a single Joule from the mains. Well, it would if it worked.
Hi Dave, Thank you for posting . As for the power units, in fact it is not worth relying on these units because the operating life is short and in fact even the design is not effective in the long run. Not to mention the fragility of the plastic case in case the user installs the box with the side screws either. As for the price per unit, the cost of manufacturing it in China is about $ 15. In the end, I would not advise anyone to buy it if he hopes to rely on it for long periods of time.
@@EEVblog Hi, of course, I can prove this 1. the quality of capacitors 2. The way they designed the electrical paths, (power rails). 3.size of the coolants, 4. don't forget that they didn't put the cooling paste between some of the parts and the coolant . 5. And don't forget the un stability of the oscillator circuit With confidence, I do not trust these circuits, especially with regard to the stability of the output voltage. I have dealt with similar units of these circuits from 5 years ago and purchased them directly from China as part of a large shipment. Unfortunately, they were not at the level required for long-term performance in terms of endurance and Most faults occur due to their dependence on the fan as a basic cooling, and the failure start with the fan. The fan stops is due to the poor quality of these fans.
@@circuitblog01 You are knowingly buying a $70 power supply here that is *built down to a price* of course it's not going to be the best quality. There is a market for everything. If you are using this at lower powers it could actually last a long time.
@@EEVblog I agree with you with on this point and that with respect to the price, it works, but I think you agree with me that we are talking about a high voltage and high ampere power units It will be a disaster for the devices connected to it in case it fails God bless you
If you only need one fixed voltage there are very cheap and powerful converters on ebay. I got one of these 1800W 40A boost converters for 20$. Works great if you want to boost your battery voltage of your Ebike. Barely gets warm with my 700 W motor load.
The title "$70 2000W Power Supply" is misleading at best, these are regulated DC-DC converters. Also, they have very little output filtering. Dunking in a large capacitor or two isn't really filtering. It won't really do much against the higher frequency noise. Though, the 3KW one has a dual phase converter, it has a pair of transistors and diodes, and also two large inductors. And according to the traces on the under side of the board, the two paths are separated from each other, so if they run 180 degrees out of phase, then they would get all the advantages there in. A dual phase converter will cut down on the output ripple fairly substantially. Also lower EMI a bit, but not much to be fair... But these are still not isolated power supplies. Since these require a fairly large DC input voltage to actually be useful, that subsequently renders them fairly useless in practice.
once i got a 10 pound power supply off ebay and it was 18v 12a and if you wanted to pull 10 amps from it you needed to ramp up the current from 3 amps and it had one of those annoying potentiometers where you need a screw driver to operate it.
Those higher voltages are starting to become common with stuff like drones and ebikes.
Ah, ok, interesting, thanks.
Still not high enough for LED luminaires.
@Dave Micolichek Obviously not, this would be for testing said motor controllers and the like.
Exactly and since ebikes are popular, batteries for ebikes become cheap so we can use them for projects. We built a remote operated vehicle that runs on a 48v ebike battery at work.
@@Lordniksidor And battery packs are relatively easy to build with 18650 batteries and BMS
I found the title misleading. It's not a power "supply" really. It's a smart DC to DC voltage and current regulator. You still have to spend the big bucks on getting your mains rectified, isolated and dropped down. I suppose you could hook it up to batteries or solar cells, but it's still not the 'supply'.
Me too. I was thinking it was such good value until i realised it was a regulator without a switch mode mains supply. Price is just ok
Rectifying mains voltage is super cheap.
if you dont need 60v, just get a 50v server power supply. for 100€ you get 3kw 60a easy
I get free mains transformers from work. No worries there.
Besides, the manual says "DC power supply", fair enough.
@@kwhp1507 and will blow up the converter and make the output live
So, are you telling me i need a power supply to power the power supply ?
AND you need a Dam to power the power station that powers the power supply that powers the power supply. Don't worry, there will be enough left for your light bulb and hot plate. Your power meter may saw a slot through your house, though. ;-)
If you really need a basic power supply you could jury rig a enclosed circuit board that plugs into the wall goes into a full wave rectifier and a couple filter caps. Probably those caps need to be rated 220v and I guess everything would be going through the rectifier. So you need a beefy rectifier. Max 1500 w from the wall ?
@@averysbragbook And how do you isolate the mains supply from the end circuit?
@@mervynjack4108 Good point. Make a 1:1 transformer might be the solution
Test, TH-cam seems to erasing my own comments on this video.
I see this comment and a few reply's to others on my end. Thanks for the video. always enjoy the content.!
Nope, I see this loud and clear.
Test 1, 2
No, can't see that! 😂😂
TH-cam knows what’s best for us
I am a radio enthusiast who monitors VHF and shortwave bands. I have very mixed feelings on some these cheap, sometimes questionable build quality switch-mode transformers used in increasing numbers in modern electronics which are unfortunately known for strong excessive RFI (radio frequency interference) My LED computer monitor which likely uses a cheap 19 volt switch mode power adapter emits widespread interference throughout the entire shortwave band likely becoming a major issue if your a Ham radio operator or receive only listener. I do have a new somewhat pricy TekPower 30 amp swiching power supply I use with my CB radio and other low or high amp 12 volt gadgets. This supply specifically designed 2 way radio use also emits some RFI but does have a nifty noise offset to tune out any self made noises it generates, but cheap poorly designed power supplies are a growing issue to radio enthusiasts.
There isn't a great deal you can do about all the junk that the neighbours have plugged in, but if you're doing anything with audio, including radio, the better bet is have a decent linear supply.
Linear supplies are generally larger, heavier, far less efficient, more expensive to buy and more expensive to post. You're not paying this price for nothing though - All these characteristics are the price you pay for very low noise output.
I have pulled the supplies out of my monitors and replaced them with a linear regulator setting the reference for a series pass transistor stage on a sheet of 1/4inch thick aluminium. It runs screaming hot, but it adds nothing to the noise floor from audio up to 440Mhz (my playground).
It IS possible to get SMPS that are very very low noise, and when I'm rich and famous, I'll go to the effort of stress testing a few. Until then, I dump money, in the form of heat, into reliable and low noise linear tech.
@David Daivdson
I am genuinely surprised that the national regulators tolerate it.
The place it is most noticeable is HF (3 - 30MHz). Yes, for amateurs it is really really annoying, but they're not the only group of people affected by this. The military of any developed nation still uses HF for long range communications that can operate "off grid". No repeaters, no satellites, no phone lines.
I can't believe that in an age where police are empowered to kick down doors over mean tweets, they allow critical infrastructure to be jammed by joke electronics.
@@digitalradiohacker I suspect that the benefit of higher power supply efficiency outweighs the higher noise floor for ham operators. Very few people use ham radios anymore anyway, at least here in the UK.
Yep, I moved to the countryside for the same reason.
This has been a problem for a long time now, but the only thing that you can do about it is drive out to a mountain top that is at least 3 miles from any civilization, then set up your HF radio gear and then drive your car a 1/4 mile away from your radio antenna or remove the battery cable so that the ECU computer shuts down all the way. Unless you have an old vehicle, pre computer era or at least OBD 1 not 2 let's face it there's more switched mode power supply's out there than you can ever imagine, all new appliances, refrigerators, washers and dryers, stoves, and then there is lights it got really bad at night because of CFL lamps (compact fluorescent lamps). But fortunately those are going away slowly, and bring replaced by LED's which still produce some noise, but not nearly as much as the CFL lamps do. The CFL lamps are bad because of the high voltage required to ionize the gas in the lamp. But TV'S and computers are horrible offenders as they have both a switching power supply, and extremely fast processors. But in addition to those there's little things like chargers for Electric razors, and Electric toothbrushes, and then medical devices such as CPAP machines, there are 2 of those in my house, and they both have those inline power brick power supply's like a laptop computer, and they're all generating noise some a little some a lot. Strangely enough one of the worst offenders I have ever come across is one of those little switcher buck converters that plugs into the cigarette lighter or auxiliary power jack in your car, and it was a really nice one triple output 4.6 amp unit. I didn't realize it was the problem at first but I was sometimes having trouble receiving my favorite Christan radio station, and not AM but FM, and a local station at that. And it seemed to be random, it would be there and then suddenly disappear. Well one day I had gone somewhere a short distance from home, I was not in my truck but a few minutes, and when I went to get out, for some reason I unplugged my phone before turning off the truck radio and most of the interference instantly disappeared so I pulled that buck conver out of the auxiliary power jack, and all the interference instantly disappeared, and I had a full quieting signal. So yes some of those things are noisy all the way up into at least the VHF band's and maybe even further. One of these days I will have a look at it with a spectrum analyzer, and just see where all it is visibly trashing the spectrum.
They didn't mess up the "V" and "U". I.E U=42V in the same way that you'd write I=42A
Jeah, he didnt notice its "I=xA" too, just like with U = xV. Shoudl it be Amps=3Amps? :D
I was under the impression the anglo sphere does not use U to designate voltage variables, but V? (which woul dbe confusing because the unit is also V, but hey, that's what it seemed to me so far)
You are right, it does seem like he messed that up, however, next to where he pointed it says CV CC, so that should be CU CC.
As a cheap load you can take some coated magnet wire and dunk it in a bucket of water. I’ve done this with kW loads
Thanks
That works much better with AC sources since it won't corrode the wire so much.
@@userPrehistoricman coated wires dont give a shit about water, ac or dc 😜
U're right. But where is he going to get
Is the Thermocouple in a TO220 package at the end of the heatsink, flapping in the breeze, measuring the output air temperature?
Nope, that's an IRF something meaning that it's more likely to be a MOSFET. However, they might be measuring temperature using that one. A bit overkill and unnecessary but who knows, Chinese wisdom maybe?
The erase of the part numbers on the chip, the markings look interesting, could it be done with a pulsed laser beam? Looks like little dots with some tiny overlapping.
Thought so
Ah! This must be it! I was puzzling over how the hell they could make a quick and easily-automatable scrubbing method that would end up looking like that.
They probably use a galvo steered beam from something like a fiber laser. Set up a fixture to register the board, program the size and location of the chips and fire away.Beats getting out a dremel.
It is lasered off. Seems to be a small pulsed qswitched (most likely about 10-100ns) high rep rate laser.
Pew pew pew
The active chips look more "lasered" than "milled". You can see the individual circles by the laser
Why would they even do that?
1. To put off competitive Chinese that want to steal the design.
2. So you can’t fix it.
Yes, that is laser engraving. There are many reasons to obscure the components. The devices are not designed to be serviced, so there is not a huge impact for consumers.
chinesium is strong in this one
top quality, only the best.
Best element on Isaac Newton table, stuper strong, many reliable
Lol 😂 😂
Higher voltages are useful for high end bldc motors and servos, they typically have flatter torque curves at higher voltages. 96v would come in handy as a cheap supply for anodizing titanium as well. I'll watch the rest of the video before I decide to I need to pick one of these up!
It is a but unfortunate that these (and other similar) "power supplies" really are just DC-DC converters.
To have a lab power supply, it would be favorable when they had a 230V AC input and isolation.
I know I can order a separate fixed switchmode supply for 60V or similar but that kind of defeats the purpose of having a cheap lab power supply.
Hopefully one time they bring out boxes with AC input (and of course with the required safety).
I use my dps5015 (50V at 15A) Power by my old arc welder transformer and a smaller transformer to drop the primary voltage to the main transformer. But the transformer from the welder has no built in magnetic shunt, so baisicly a normal transformer just a huge ~1500W one.
Yeah, it'd be great to use the ready supply of AC at these power levels. You're not going to find an old laptop/pc power supply putting out 2kW. Maybe rip the transformer out of a microwave, but then you're getting sketchy as. For a "lab" power supply I'd rather something that's reliable, linear and self-contained. But I rarely need >100W
@@MrSnoots you probably dont want to do this. those transformers are designed to be "lossy" and you have to hack in somehow a new secondary. finding a transformer which does 2KW can be a tricky task. but im still not fully convinced that it can handle the 2 kW anyway. maybe more 2 chinese kW
@Robert Slackware bur rewind the secondarys or you will get a "very shocking" experience. But still they are only in the 500W range.
@@lukahierl9857 Shocking indeed! More like a shocking and skin-burning experience.
You can tell it is Chinese whenever there is a"technical parameters", seems like nobody can get this translate to the more common technical specifications
I like the Ibput voltage, personally
You can tell it's Chinese if you end up buying it after watching TH-cam.
I prefer the "Operationg Instructions." That's another common translation error I see in a lot of products.
43:45 So it blows the hot air towards the caps? Nice!
the wireless modules are standard NRF24L01 2.4ghz modules
They look fake with that black blob.
3:30 e.g. stepper driver (CNC) are in this range
Dave, please, test these two devices for max load. I understand that won't be easy, but possible. At least you can connect a number of your PSUs outputs in series to achieve higher voltage to supply DUT, then load it with some ballast resistor (nichrome wire wound). Thanks.
You should have increased the Hameg output voltage by a bit as you will have less than the 20V at the Juntek input because of the cable voltage drop.
Mikeselectricstuff did a “dummy load in a bucket” video some time ago. I really want to see if these things can handle what they claim or if they explode/catch fire!
They work good! Heathkit now MFJ has been making 50ohm transmitter load for years. These units are set in oil.
halogen globes work well for plain ol DC
Is that meant to be JunkTek?
Those exact words kept running through my mind, every time I seen it!
Maybe Junket
That's what I thought it said when I first looked at them!
no u
It turnes your tech to junk when IT crashes
19:30 Still not as bad as a Hakko soldering iron with digital interface. Two buttons.
Hey, they could have done everything with one button but were super generous and decided to give double the necessary buttons.
That is the one thing I do not like about my Hakko; it has to be some of the worst UX design I've come across recently.
Makes you wonder when a 105V input supply has a 100V rated capacitor across it/s input. I know they survive modest overload but that's not good practice surely?
IRFP4110PBF MOSFETs used in these DC/DCs are also 100V rated. ;)
They are not rated for how long they need to operate at 100V. I guess three seconds is long enough? 😂
The weirdness you were having seems like it could be from the voltage drop across your input wires. The voltage that ends up at the input is likely less than the minimum input voltage of 20V. How about re-doing some of your tests, but feeding it say 30V or more from your supply?
At 23:00 one can see about 130-140 W on the R&S power supply, when 100 W are being pulled from the Juntek. That's
Hook up some lead acid batteries in series, that should provide the needed umpf...
Deep cycle batteries would do the job quite well enough...
Considering the cooling, I'd say those are peak numbers, also, a set od high performance RC batteries shouldnt have a problem with few kWs
At 39:30 Dave plugged the RS485 terminal unevenly, I can't wait to see the brick fail when power applied
Yep, i saw that too
For testing higher loads, you could use a string of SLA batteries in series for the DC input supply, plenty of current on tap. Just 4 of them from a typical UPS will give you 48V.
90 Vdc was also used for the old "farm" tube radio receivers from the 1940"s that used a 90 Vdc power supplies.
That top to bottom Via stitching is probably significantly helping reduce the resistive losses, because the vias are filled with solder and hence can carry current laterally ie across their diameter! So instead of the current just flowing through the top and bottom layer copper, it can also flow inplane across each via, and as the via's are very close together, they will act as a reasonable, "conductor" of some equivalent thickness to the pcb itself (1.6mm) rather than just the thicknesses of the top and bottom traces (~ 0.07mm for 2x 1Oz layers)
Old telecom rectifiers is the first thing that comes to mind to feed these little units. Not a problem finding something that can pump out a few KW!
0-50 amps.... Anyone after a welder😂
But not with high frequency start!
Dave, pretty please with ice cream, cherries and frosting on top; Give it the beans, FULL POWAAAA!
This would be perfect for a parralel resonance induction heating project for small parts I'm working on. It would be absolutely perfect if it works but as cheap as it is, it's still a good bit of money in the current climate (cough!) and I'd hate to be waiting around for 40 days (the stated max delivery time) only to find out it doesn't work.
-Charlie, a fan on the other side of the of the boarder lock down
The interface on the remote box is very similar to the RuiDeng (RD Tech) stuff
Last year I had the big luck to get a new, original packed
Cisco Systems PWR-C45-2800ACV Catalyst 4500 2800W AC Power Supply for less than 50 €
(2800W +3,3V/12,1A, -50V/28A, +12V/113,3A)
It is a power monster. It has no on/off switch but there are how to´s in the net.
Dave becomes lazy, he had all the equipment to test dropout voltage. Two minute test. I liked his videos for their entertainment _and_ educational value. That last point gradually diminishes. Then what, unboxing videos? Yes, I'm a little grumpy now. :)
16:02 - almost looks like laser pulses were used to erase the chip faces. would make sense as it would be a rapid process to erase an entire board in a few seconds.
Hi guys,
I just bought this device: the DPM8608-RF
I was wondering if you other owners have the same problems like me:
When turning on the device, the output is always short-circuited for a few seconds, during the boot-process (when the fan runs for a few seconds).
With the "Fast-speed discharging" function enabled, the output is short-circuited in the idle state (output off) continually.
This does not happen when the "Fast-speed discharging" function is disabled.
Only when the output is switched on (press OK), the output gives power like you would expect and there is no short circuit of course.
In both cases the charger is supplied by an external power supply and is switched on.
Secondly there are extremely high inrush currents on the input and output.It happens when connecting the charger to a power supply in the input side, when the power-switch is in the on-state. Also the device reboots every 2 seconds when the power supply is connected from a powerless state, and the power-switch was already in the on-state.It also happens when connecting a battery to the output.
Please watch my videos, by clicking on the following links:
1. "Fast-speed discharging" function enabled: photos.app.goo.gl/2Rjre5GXnTh81FZY8
You see a 18650 battery connected to the output of the device. I connected a little motor as a reference to visualize the short-circuit. When I turn on the device in de idle-state (no power on output), you see the motor turning, because it is fed by the battery in the closed loop. This is because the output is short-circuited.
2. "Fast-speed discharging" function disabled: photos.app.goo.gl/caLsksMpYfHZzR2r6
When powering on the deice, the motor is running for a few seconds and is fed by the battery in the closed loop. Again, this is because the output is short-circuited.
A lot of fairly high power audio amps have quite high voltage rails, I think a Sansui 9090 has +/-75VDC rails
Appreciated the video retaining the UPs & DOWNs... it is real life after all. Good on you.
👍😎
32:32 I've tried on multiple occasions and have been unable to find cheap knobs without markers (mainly for use with rotary encoders) on eBay or aliexpress.
My first test for a power supply with maximum rated output voltage above 12V is to take it *straight* out of the box, take my #4 jumper wires with banana plugs or fork terminals (got both), and use those to hook up the output to my car’s battery. If some magic smoke escapes or if it doesn’t power up after that - I put it nicely right back in the box and ship it back. There were a couple HP supplies a while ago that didn’t pass that test, sadly. Can’t remember the model, sorry. This may sound like an arbitrary test but I really had very few problems with the models that were immune to being back driven from a source with a couple hundred amps of short circuit current capacity. It was my Hogwarts sorting hat for power supplies.
why 96V? propably because you can setup 2x48V power supplys in series.. it is cheaper than buy one 96V(or somewhere around that)
Can you put in series buck converters? I wouldn't want to try that.
@@unperrier i think if they are isolated?
Impressive, particularly with that wifi toggle box included but I reckon an AC to DC converter that could play along at those power-altitudes, would take it to a completely another price ballpark.
For Titanium anodization, the color is set by the voltage, blue is down around 20V, green is around 100V
junktek - WHAT A NAME!
Incredibly promising! :)
Very much like the very tasty very old desert.
Very much like the very tasty very old desert.
The problem with all of these switching power modules is that they don't convert from the AC line, but require a high power DC input. Without a converter from the line they are useless as a bench supply.
Yeah, I can't think of any path to an isolated DC supply of that magnitude that doesn't at least double the cost. Even something like a few car batteries or used server power supplies in series add up. Still probably a screaming deal, but you have to keep in mind the price of a usable assembly here, not just the core component.
I'm waiting to see what color that bench mat will change to next. Brown?
96v is maybe for high voltage e-bike battery packs ?
60v is maybe for 48v - 55v lithium solar banks (50A for fast charging)
24S max
110v is a common voltage used in substations and switchgear automation in most countries
It's not the question if it can provide the output power. The question is for how long.
@Robert C not only Chinese products. Just something that applies to everything that has to dissipate heat
96V at 10 amps is what my ALC 60x Ar-Ion laser needs. Nice to see this available.
Nvm.... these things should be as far away from a laser as possible...
Hello. The wireless module is a nrf24l01. I had a couple of them from ebay.
You can send one of them to me in the states and I'll put it thru its paces. I have 2 higher power capable supplies, one 60V/50A @ 2500W max. and one 20v/115A 2800W max., both running off 240vac single phase. The 2500W is rated for 3KW but only when running off 3-phase power. I have a Transistor Devices electronic load that will do 600V/400A @ 4000W!
You can pick up 48v server supplies off Fleabay relatively inexpensively which would be a great way of powering one of these supplies (regulators).
Damn! That electronic load must be enormous
I have the opposite problem. I own a 20.5 + 20.5 Vac 30 +30 amp iron core transformer and all the filtering capacitors and rectifiers... A linear regulator would be an insane waste of power!
Should test the dynamic response of the power supplies, say 2A to 20A at 1KHz.
Buy an Intel 1600w server 12v supply from EBay for like 30 bucks
Good review. I could not read the SSD on the unit as the background LEDS were same as the active LEDS.
10:56 So, you will need a power supply for your power supply. Not so handy. It would be nice if it just plugged into mains.
I often use voltages between 60 and 120V to anodize titanium ;)
Interesting, I thought that was low voltage high current stuff?
@@EEVblog I guess it's like that for aluminium. With titanium you get colours with the oxide layer on it's own and the higher voltages colours are more resistant to fingerprints and skin oils, so thats what I use. Just google "titanium colour chart" if you are interested.
I've seen scratched out chips on other Chinese electronics, I believe they do it so other companies can't steal their design and make a even cheaper knock off.
It's a theory of course but since they do it on all products regardless of price level I think it does hold some water.
I suspect that on these super low price items the scratcing might be to conceal that the chips are actually name brand chips that failed QC and were meant to be destroyed, but which the Chinese manufacturer sold off cheaply (and illegally or at least gray zone) to make a few extra bucks.
@@reffyfikserting Do they actually do that? I've heard this before but never seen proof or sources that do it.
I do not understand why/how caps on the output can dump anything when the supply shuts down. That big cap will already be at output potential and will only be able to hold up the rail for a small time (and wreck-up its step response). There would need to be something that is storing energy at a higher potential that gets released after the regulation circuit shuts off. Perhaps the input cap gets suddenly connected to the output due to improper FET failsafe? I have seen it before where a micro controller brownout caused all the I/Os to change to default tri-state and that caused connected circuit to misbehave... badly.
Lesson here: Dont send your stuff to Dave tests if it docent meet specs. Dave will find out.
If you need to control a lot of current it's a good value. Non-isolated design isn't critical since the power supply that is running it should take care of the mains isolation.
The only educational content I get from this video is "electronic loads suck".
Not trying to sound negative, but isn't it a bit misleading to call a buck converter a "power supply"? It's sorta like calling your car's transmission the engine.
A "power supply" at a bare minimum is one that lets you program the output voltage. A "Lab power supply" lets you set the voltage and current. This supply does both, so it's *clearly* a "power supply".
Just because it uses a buck topology is entirely inconsequential. In every linear lab power supply on the market is essentially a "buck", because it reduces and regulates the voltage.
@@EEVblog Don't you have to HAVE the voltage first? i have been looking for inexpensive 48 volt DC power supplies with 25 to 90 amp outputs for a few years now and they are pretty hard to find. And---- your title didn't say "Lab" Also, just for the sake of discussion, I'd say that "bare minimum" (YOUR term) should start with the Power not the controls. I don't have to win this exchange. I just wanted to give you my not quite novice opinion as a fairly regular viewer.
@@frenchcreekvalley they're pretty easy to find, get a used blade server PSU.
@@EEVblog - and Dave misses the point completely! This device doesn't take MAINS AC power and convert it to DC - it requires an additional *power supply* to operate!
At 17:45 you show the separate *power supply* that you used to test it with.
By that logic, wouldn't the electrical power plant be your power supply? Everything else is just transmission and conversion.
I like the way you analyze this equipment. You get what you pay for.
Maybe i'm wrong but you interpret the input voltage spec as a requirement to be able to achieve the output voltage. I interpret that as the maximum voltage the psu can take. I don't think you can use those ratings to determine the voltage drop the psu will generate
over here in the USofA you could probably get away with using a decently large auto-transformer to drop the mains and rectify it to get ~110VDC... only issue would be input/output would be mains referenced and not isolated in any way
You can use a transformer n rectifier set up from a treadmill. They use 130v dc motors. That could easily supply any of these the mains ac/dc power at decent amperage.
The issue with the fan is that it is non-variable speed, and current-controlled not temperature-controlled.
at 110v AC in the US... max residential power usage is about 1800W ... I think that's why most portable electric heaters max out at 1800W.
At first look I read JunkTek. The remote control is for your distance safety when the thing blows up.
96V is often a nominal voltage for train equipment. We use these HV PSUs for powering DUTs
Server "common slot" power supplies can be wired in series/parallel to create massive DC supplies. Check e Bay for a DPS-800. For around 20 bucks used, it'll put out 1kW with a 240VAC input and 12V at 83A output. They do current sharing so you can parallel them to make high current supplies. Open the power supplies up and by using fiber washers and/or nylon screws you can isolate the supplies so that they can be wired in series.
I've got six and by using the mating "hot plug" connectors (salvaged from some HP server backplanes), I can put them in one config for a 6kW 12V 500A supply (for testing car inverters), or I can put them in series as a 72V 83A supply to power a DeWalt 60V chainsaw. (I have it fused at 30A and wired with 10AWG SOOW wire but it's ice if I need to do alot of cutting.)
Oh yeah, they are NOT quiet but what do you expect for a server power supply?
I use 2 or these server supplies in series for a 25 Vdc 83 A source for my various buck/boost converters for bulk charging and testing. Bought mine for $15 each delivered, then did the magic with the pins to make them isolated. Nice 2000 watt supply 😃
Please change the name. You can see JunkTek a mile away.
No.
Yeah good DC/DC converters are getting cheap. But the expensive part will always be the AC/DC conversion (and doing it properly)
I know that you sometimes need high voltage for laser diode banks or even normal big LEDs
First of all, the VIAs distribute heat so all the heat can be transfered to the side with the better cooling.
The VIA Stitching is actually called "Cheese holeing".
First of all, the holes reduce the inductivity of the trace which is not only neat for RF (Processors) but also comes in handy for high currents.
Also it prevents "current strings" where all the current tries to narrow down in a tight path creating an immense current density and melting spots of the trace. With all the vias, the current is distributed more evenly over the width of the trace.
Hi, there is fw updates for DL3021 series, overshort problems etc... We had problems one test device at DL3021 overshorting. Rigol send whole new unit and it was B revision.
It's weird seeing wattages that sound too high to be legal. In NZ, you'd need to plug this into your electric stove to get 3kw @18 amps, as our wall sockets are at 10 amps max! Where I live the 1945 transformer puts out ac at 239 to 242 volts depending on time of day.
41:31 Look at how the inductor windings are almost shorted together! The long un-enameled leads are almost on top of eachother! Yikes! Just a small jiggle in shipping and you might get a dud. I noticed that the inductor in the smaller unit had the same issue, but not nearly as bad.
Those are conected on the pcb
@@lukahierl9857 38:56 So they are!
The 96 volts may come handy in tv's backlights strips, of course no need for the full 20 amps in that application
Or driving high voltage motor stuff
@Dave Micolichek 90V DC motors are not uncommon.
That’s what I was thinking! My last TV died and I had no easy way to check if the backlight was working because it was like 75 volts or something. However, this is the only time I can think of where a 60-96V supply would have been handy for me
Dave Micolichek, it definitely depends on the model and maybe even the country. The last TV I took apart had a 57.8V rail for the LEDs
@Dave Micolichek But this one you can use for more than just a tv backlight
I would think you could use the higher voltages for working with strings of LEDs which can run in the 90v range.
This looks like exactly the kind of thing I was thinking I might have to design from scratch, for charging a 48V battery bank with current limiting depending how much power is available from a Solar inverter, so I can be sure not to take a single Joule from the mains.
Well, it would if it worked.
Hi Dave, Thank you for posting . As for the power units, in fact it is not worth relying on these units because the operating life is short and in fact even the design is not effective in the long run. Not to mention the fragility of the plastic case in case the user installs the box with the side screws either. As for the price per unit, the cost of manufacturing it in China is about $ 15. In the end, I would not advise anyone to buy it if he hopes to rely on it for long periods of time.
Why do you think it's going to have short life? Try to quantify claims like this.
@@EEVblog
Hi, of course, I can prove this
1. the quality of capacitors
2. The way they designed the electrical paths, (power rails). 3.size of the coolants,
4. don't forget that they didn't put the cooling paste between some of the parts and the coolant .
5. And don't forget the un stability of the oscillator circuit
With confidence, I do not trust these circuits, especially with regard to the stability of the output voltage. I have dealt with similar units of these circuits from 5 years ago and purchased them directly from China as part of a large shipment. Unfortunately, they were not at the level required for long-term performance in terms of endurance and Most faults occur due to their dependence on the fan as a basic cooling, and the failure start with the fan. The fan stops is due to the poor quality of these fans.
@@circuitblog01 You are knowingly buying a $70 power supply here that is *built down to a price* of course it's not going to be the best quality. There is a market for everything.
If you are using this at lower powers it could actually last a long time.
@@EEVblog
I agree with you with on this point and that with respect to the price, it works, but I think you agree with me that we are talking about a high voltage and high ampere power units
It will be a disaster for the devices connected to it in case it fails
God bless you
If you only need one fixed voltage there are very cheap and powerful converters on ebay. I got one of these 1800W 40A boost converters for 20$. Works great if you want to boost your battery voltage of your Ebike. Barely gets warm with my 700 W motor load.
The title "$70 2000W Power Supply" is misleading at best, these are regulated DC-DC converters.
Also, they have very little output filtering. Dunking in a large capacitor or two isn't really filtering. It won't really do much against the higher frequency noise.
Though, the 3KW one has a dual phase converter, it has a pair of transistors and diodes, and also two large inductors. And according to the traces on the under side of the board, the two paths are separated from each other, so if they run 180 degrees out of phase, then they would get all the advantages there in. A dual phase converter will cut down on the output ripple fairly substantially. Also lower EMI a bit, but not much to be fair...
But these are still not isolated power supplies. Since these require a fairly large DC input voltage to actually be useful, that subsequently renders them fairly useless in practice.
I would like to see a video where you sort out that switching noise on the output :P
Well, 96V which is 2x48V - a very common voltage for power supplies nowadays.
96V 20A is good for most E-bike controllers and the new craze of e-unicycles if you need to slowly power on a controller for repair.
I'm wondering who the customers are for that converters. I can't imagine any industrial field of application where I would install them
It's not super common but 90V is sometimes used in CNC stepper motors. Although normally you wouldn't need an adjustable power supply for that.
Dave, why you do not make open source electronics project series on your channel any more? Like lab PSU back then.
I'd love to see spectrum analyzer measurements, both conducted and radiated, as these supplies are often great RFI generators.
Please put the model number in the title or the video description - the link leads only to the store of the manufacturer.
Was that a track repair on a new PCB? 16:38
Couldn't you use an electric heater coil as a high power load?
Anodizing titanium is a good use of precise higher DC voltages.
There are some Dayton DC motors that are 90V
once i got a 10 pound power supply off ebay and it was 18v 12a and if you wanted to pull 10 amps from it you needed to ramp up the current from 3 amps and it had one of those annoying potentiometers where you need a screw driver to operate it.