Mine's just arrived so I've tested it for the power-on spike. Hooked my scope probe up directly to the terminals in case you were seeing some sort of RF induction effect in the wires (certainly they pick up a lot of noise...), but yeah I see it too. It varies in intensity, I've seen anywhere from 5V to 7.5V pp. It's all over very quickly - a rapid oscillation for maybe 200ns, followed by a couple of microseconds of slower ringing fading away to nothing. It seems to make no difference whether negative is bonded to earth or not. I can't make it light up (or blow up!) an LED though so perhaps despite the voltage, no current can actually flow, or perhaps it's just too short to see it. But I guess for safety's sake it's probably prudent not to have anything connected when powering on. Fortunately the actual output power switching looks pretty clean.
I could do with modifying this thing to either have an extra power switch or just a bit more advanced would be to have the first power output to trigger another switch like a transistor and then wait 1 or 2 seconds before allowing the power through. More of a safety thing and avoid breaking stuff. Really glad I found this video and i am going to check mine to see if its blasting spikes out.
It's normal for the voltage to fall slowly at switch off if the load current is small. all bench power supplies have large capacitors across the output to provide a low output impedance, typically a few thousand microFarads. Your voltage fell by about 3V in 0.2 seconds with a load current of 50mA. This implies that the output capacitor is 50mA x 200ms / 3V = 3333uF. The voltage falls relatively linearly while your load is working and taking a constant current and then slows down to an even smaller rate of fall at about 2V when your load stops operating.
It might not be too surprising seeing a spike when turning on/off the unit. What would be more interesting is turning on/off the output when the on/off switch is powered on. If there is a spike then the PSU is a no go. One question, when the power on/off is switched on, does the output default to no output, so the output switch/button needs pressing? As the unit is rated at 10amps, testing at 10V and 10 amps (a car headlight bulb would do) and then check for the ripple, would show how clean the output is under load.
I suspect that the spike observed at switch-on is not actually appearing across the output of the power supply. It may be induced in the wires connecting it to the scope by radiated coupling from the mains switch. You might even see a similar effect if you switch a room light on. To test this you could connect the scope directly to the PSU terminals and twist the scope earth lead tightly around the probe to minimise the loop area which picks up the radiated emissions. Radiated spikes like this are not harmful because they have a very high impedance and cannot transfer much energy. The decoupling capacitors in your load circuit will protect it. You do have decoupling capacitors don't you?
This was mostly just testing against an oscilloscope. In terms of the circuit being protected by capacitors like that, I didn't but that is a good idea. Thanks.
Hello, I usually prefer to film in widescreen. I filmed that part with a smartphone - and only in edit did I see it would do that - it was a little frustrating. The smartphone is the clearest camera in my home lab - and has rather good audio.
@@Orionrobots Thank you! I have a WSP 120v 3A power supply. by replacing the RA1 resistor, I managed to get 10A at 30 V, but the standard ammeter shows 1A = 3A. I want to try to calibrate the standard ammeter.
This was REALLY useful and educational! It is very good to know that it will generate that voltage spike when it is turned on! It seems to me that they did not include some actual(ly) sound activation circuitry - it obviously needs something like a delay so that the main actual power supply circuitry gets that little bit of time to level, even out. Maybe that spike even is a side effect of the output activation circuitry itself! THAT of course would be rather terrible, wouldn't it! Anyway, I am only guessing here at to what it could be caused by (and what it should be prevented by - as an addition to the circuitry that has not factually been included - preventes from being possible to occur, even. It seems to be some kind of discharge.. it must be! Somehow I also wonder if the word 'static' got any place in the equation.. but than, even though it must oftentimes will receive the electricity it charges up a different way (it would not really matter), all types of capacitors store their charge statically ("as static"?) of course, so the discharge of a(ny) capacitor by definition would be a static discharge, so to say.
Hello, the keyboard is a Jelly Comb wireless keyboard for a Mac. It can switch between 3 wireless devices, and charges via a micro-usb port. I've had it for a couple of years now, but I've used it to write 2 books, lots of code, a few magazine articles and play Fortnite. Some of the keycaps, especially A,S and D are a bit worn on it. The one flaw - sometimes the "Fn" key glitches on it.
So are the outputs floating and you can connect the probe directly to the powersupply (clip on neg and probe on positive)? Apologies is this is a dumb question, im new to this and have seen videos where is the power supply is not isolated it can make things blow up if the ground is shared with oscilloscope
The green terminal is earthed, the negative isn't necessarily and could be isolated. So to be totally sure, you might want to connect the negative through to the green if you mean it to be earth referenced.
Be careful, the power supply itself is grounded, but the output isn't (floating), so as long as you don't make a connection to the case of the powersupply working with an Oszilloskop on the power draining objekt connected to this unit, it should be safe. I myself are always working with an Isolation transformer if grounding is not clear
Hey Danny. Karl B here. Good to know about that spike at power on without the output enabled. That would potentially fry a lot of stuff. I’ve been thinking of picking one of these up for some of my retro computer projects, but I don’t know if I’ll take the risk now - especially as it’s hard to get a lot of the old chips these days. Could the smoothing capacitors account for the lack of a spike during your later testing?
Hi Karl! I will need to investigate these spikes more - was it the device, or was it me? Definitely keeping an eye on this as I also don't want to blow any chips with it.
@@Orionrobots Pretty sure it wasn’t you, dude. Looks like you just need to be careful. Maybe you could enable the output, let it settle, and then connect it to your circuits. I’m with you though, as I usually want to connect to old chips that can’t easily be replaced these days. I’ve already blown a VIC-II chip recently, and those guys are in short supply these days!
@@SuperFurry68A ouch - a VIC-II is harsh. I'm doing a lot with a Raspberry Pi Pico - but still don't really want to let the magic smoke out. The bench supply does stop me from having to question battery freshness, but it would be great ot be able to trust the output power on startup more
You'd have to check the manual. There's over currnet protection on there. My main usage of it since opening has been as a voltage source with some current monitoring, for robots when testing motors, power regulators or various boards. I've rarely used the current dial, but that may just be my use case.
Got one of these for Christmas. I can't figure out if there's a way to put it in constant current mode. The CC lights up briefly but quickly changes back to CV mode
@@maebeans The current limiting worked well for me when I was using this power supply to test my automatic nerf dart launcher with. This was helpful as one motor was faulty and had to be changed - the rollers wouldn't go, and upon testing with a mutlimeter, it turned out that one was actually shorting completely. The roller motors were incredibly cheap hobby motors.
Ratings tend to come in two flavours - "it was amazing" or "it was the worst thing ever". This one was ok, did the job. It has flaws for certain, but it's working for me at the moment.
The spikes are disappointing, but otherwise the supply is working for me and I've now used it for a few projects. For example ruclips.net/user/shortshieLF3K6hrs.
It works for my purposes - mostly powering small things on breadboards. If I am using a Raspberry Pi or similar, then a USB power supply is preferred, but when testing motors this definitely helps. It'll save me a small fortune in batteries (that and the new charger).
Mine's just arrived so I've tested it for the power-on spike. Hooked my scope probe up directly to the terminals in case you were seeing some sort of RF induction effect in the wires (certainly they pick up a lot of noise...), but yeah I see it too. It varies in intensity, I've seen anywhere from 5V to 7.5V pp. It's all over very quickly - a rapid oscillation for maybe 200ns, followed by a couple of microseconds of slower ringing fading away to nothing. It seems to make no difference whether negative is bonded to earth or not.
I can't make it light up (or blow up!) an LED though so perhaps despite the voltage, no current can actually flow, or perhaps it's just too short to see it. But I guess for safety's sake it's probably prudent not to have anything connected when powering on. Fortunately the actual output power switching looks pretty clean.
I could do with modifying this thing to either have an extra power switch or just a bit more advanced would be to have the first power output to trigger another switch like a transistor and then wait 1 or 2 seconds before allowing the power through. More of a safety thing and avoid breaking stuff. Really glad I found this video and i am going to check mine to see if its blasting spikes out.
I bought 2 of these to get a split supply and works great
It's normal for the voltage to fall slowly at switch off if the load current is small. all bench power supplies have large capacitors across the output to provide a low output impedance, typically a few thousand microFarads. Your voltage fell by about 3V in 0.2 seconds with a load current of 50mA. This implies that the output capacitor is 50mA x 200ms / 3V = 3333uF. The voltage falls relatively linearly while your load is working and taking a constant current and then slows down to an even smaller rate of fall at about 2V when your load stops operating.
Great content brother, keep up the good work!!
It might not be too surprising seeing a spike when turning on/off the unit. What would be more interesting is turning on/off the output when the on/off switch is powered on. If there is a spike then the PSU is a no go. One question, when the power on/off is switched on, does the output default to no output, so the output switch/button needs pressing? As the unit is rated at 10amps, testing at 10V and 10 amps (a car headlight bulb would do) and then check for the ripple, would show how clean the output is under load.
Inrush current this is a soft starter, nice to meet you!
I suspect that the spike observed at switch-on is not actually appearing across the output of the power supply. It may be induced in the wires connecting it to the scope by radiated coupling from the mains switch. You might even see a similar effect if you switch a room light on. To test this you could connect the scope directly to the PSU terminals and twist the scope earth lead tightly around the probe to minimise the loop area which picks up the radiated emissions. Radiated spikes like this are not harmful because they have a very high impedance and cannot transfer much energy. The decoupling capacitors in your load circuit will protect it. You do have decoupling capacitors don't you?
This was mostly just testing against an oscilloscope. In terms of the circuit being protected by capacitors like that, I didn't but that is a good idea. Thanks.
But he DID measure these spikes from the output connection points (or however one should say that)!
great videos, just found your channel. Only one request, could you shoot in wide screen mode and not portrait? as much easier to view
Hello, I usually prefer to film in widescreen. I filmed that part with a smartphone - and only in edit did I see it would do that - it was a little frustrating. The smartphone is the clearest camera in my home lab - and has rather good audio.
Hello ! Help please, could you send a photo of the control board, where you can see the values of the components?
It seems like there’s a few requests about the innards and further parts of this supply. I plan to make a follow up video.
@@Orionrobots Thank you! I have a WSP 120v 3A power supply. by replacing the RA1 resistor, I managed to get 10A at 30 V, but the standard ammeter shows 1A = 3A. I want to try to calibrate the standard ammeter.
This was REALLY useful and educational! It is very good to know that it will generate that voltage spike when it is turned on! It seems to me that they did not include some actual(ly) sound activation circuitry - it obviously needs something like a delay so that the main actual power supply circuitry gets that little bit of time to level, even out. Maybe that spike even is a side effect of the output activation circuitry itself! THAT of course would be rather terrible, wouldn't it! Anyway, I am only guessing here at to what it could be caused by (and what it should be prevented by - as an addition to the circuitry that has not factually been included - preventes from being possible to occur, even. It seems to be some kind of discharge.. it must be! Somehow I also wonder if the word 'static' got any place in the equation.. but than, even though it must oftentimes will receive the electricity it charges up a different way (it would not really matter), all types of capacitors store their charge statically ("as static"?) of course, so the discharge of a(ny) capacitor by definition would be a static discharge, so to say.
One interesting thought here were the responses pointing out that it was a zero-load test, which could be why there's a spike.
What model of keyboard do you use? Looks amazing.
Hello, the keyboard is a Jelly Comb wireless keyboard for a Mac. It can switch between 3 wireless devices, and charges via a micro-usb port. I've had it for a couple of years now, but I've used it to write 2 books, lots of code, a few magazine articles and play Fortnite. Some of the keycaps, especially A,S and D are a bit worn on it. The one flaw - sometimes the "Fn" key glitches on it.
So are the outputs floating and you can connect the probe directly to the powersupply (clip on neg and probe on positive)? Apologies is this is a dumb question, im new to this and have seen videos where is the power supply is not isolated it can make things blow up if the ground is shared with oscilloscope
The green terminal is earthed, the negative isn't necessarily and could be isolated. So to be totally sure, you might want to connect the negative through to the green if you mean it to be earth referenced.
Be careful, the power supply itself is grounded, but the output isn't (floating), so as long as you don't make a connection to the case of the powersupply working with an Oszilloskop on the power draining objekt connected to this unit, it should be safe. I myself are always working with an Isolation transformer if grounding is not clear
Hey Danny. Karl B here. Good to know about that spike at power on without the output enabled. That would potentially fry a lot of stuff. I’ve been thinking of picking one of these up for some of my retro computer projects, but I don’t know if I’ll take the risk now - especially as it’s hard to get a lot of the old chips these days. Could the smoothing capacitors account for the lack of a spike during your later testing?
Hi Karl! I will need to investigate these spikes more - was it the device, or was it me? Definitely keeping an eye on this as I also don't want to blow any chips with it.
@@Orionrobots Pretty sure it wasn’t you, dude. Looks like you just need to be careful. Maybe you could enable the output, let it settle, and then connect it to your circuits. I’m with you though, as I usually want to connect to old chips that can’t easily be replaced these days. I’ve already blown a VIC-II chip recently, and those guys are in short supply these days!
@@SuperFurry68A ouch - a VIC-II is harsh. I'm doing a lot with a Raspberry Pi Pico - but still don't really want to let the magic smoke out. The bench supply does stop me from having to question battery freshness, but it would be great ot be able to trust the output power on startup more
I can''t seem to find the way changing from CV to CC on this Power supply.
Thanks for the video BTW
You'd have to check the manual. There's over currnet protection on there. My main usage of it since opening has been as a voltage source with some current monitoring, for robots when testing motors, power regulators or various boards. I've rarely used the current dial, but that may just be my use case.
Got one of these for Christmas. I can't figure out if there's a way to put it in constant current mode. The CC lights up briefly but quickly changes back to CV mode
I've been able to limit current, but also not found a constant current mode.
@@Orionrobots turn on the meter and set its output to
@@maebeans The current limiting worked well for me when I was using this power supply to test my automatic nerf dart launcher with. This was helpful as one motor was faulty and had to be changed - the rollers wouldn't go, and upon testing with a mutlimeter, it turned out that one was actually shorting completely. The roller motors were incredibly cheap hobby motors.
Will it do constant voltage and constant current? Ta
I think it will do either of those.
Why do all of these power supplies have bad ratings on amazon?
Ratings tend to come in two flavours - "it was amazing" or "it was the worst thing ever". This one was ok, did the job. It has flaws for certain, but it's working for me at the moment.
I am a laboratory DC power supply R&D and production factory,
Please contact me if needed.
Truly disappointing. Great job on finding pre-output spikes.
The spikes are disappointing, but otherwise the supply is working for me and I've now used it for a few projects. For example ruclips.net/user/shortshieLF3K6hrs.
Hi are you still happy with power supply?
It works for my purposes - mostly powering small things on breadboards. If I am using a Raspberry Pi or similar, then a USB power supply is preferred, but when testing motors this definitely helps. It'll save me a small fortune in batteries (that and the new charger).
@@Orionrobots Thanks.