New miniature programmable DC power supply - FNIRSI DPS-150

[4thDoctorWhoFan]

I have yet to use the barrel jack as so far I have only powered it via USB-C.

Did you get the one with the official USB adapter?

No, I purchased the power supply only.
I already have around 4 USB adapters that are more than sufficient.

[Aldo22]

Do I understand correctly that it is not a step-up converter?
That is, the highest output voltage is equal to the input voltage?

On mysku there is a picture of the ripple/noise which doesn't look very good.
200mVpp is a lot.
Was it measured wrong, or how come?
Fnirsi says "<20mV ripple to protect sensitive electronics". But what's that? Vpp/Vrms?

[4thDoctorWhoFan]

Do I understand correctly that it is not a step-up converter?
That is, the highest output voltage is equal to the input voltage?

On mysku there is a picture of the ripple/noise which doesn't look very good.
200mVpp is a lot.
Was it measured wrong, or how come?
Fnirsi says "<20mV ripple to protect sensitive electronics". But what's that? Vpp/Vrms?

I don't know what to tell you.  To many unknowns about what you posted.
All I know is that I don't have those sort of results.

[Aldo22]

I don't know what to tell you.  To many unknowns about what you posted.
All I know is that I don't have those sort of results.

OK, but the first question is easy.
If your voltage source supplies e.g. 12V, can this device supply e.g. 20V or only 12V or less?

The other question relates to the review here:
https://mysku-club.translate.goog/blog/aliexpress/101049.html?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp

Thank you!

[ArdWar]

Reading the manual (lol), this is buck only.

I'm also not sure which "reverse output protection" they're advertising. Likely just voltage since they still warn user to use protection diode if there's possibility of inadvertent quadrant 2 operation.

[Aldo22]

Reading the manual (lol), this is buck only.

OK, thank you!
Congratulations on your 666th post. 

[Fungus]

Do I understand correctly that it is not a step-up converter?

Yes, that's correct.

Input voltage must be higher than output voltage.

[ptluis]

Do I understand correctly that it is not a step-up converter?
That is, the highest output voltage is equal to the input voltage?

On mysku there is a picture of the ripple/noise which doesn't look very good.
200mVpp is a lot.
Was it measured wrong, or how come?
Fnirsi says "<20mV ripple to protect sensitive electronics". But what's that? Vpp/Vrms?

Try to power the device from battery source and then take measures 200+mV are excessively high. I had one and the ripple values were around 28mv from battery source.

And if you supply it with 30V you won't get 30V at output mine did 28.6V

I return it because I work with higher voltages

[Fungus]

Do I understand correctly that it is not a step-up converter?
That is, the highest output voltage is equal to the input voltage?

On mysku there is a picture of the ripple/noise which doesn't look very good.
200mVpp is a lot.
Was it measured wrong, or how come?
Fnirsi says "<20mV ripple to protect sensitive electronics". But what's that? Vpp/Vrms?

Ripple is periodic, you're looking at "noise".

At 20uS/div? I wouldn't like to say where that's coming from but the PSU should have a big capacitor across the output so it seems unlikely to be the PSU per se. Try switching some other things off.

[Fungus]

Try to power the device from battery source and then take measures 200+mV are excessively high.

[ptluis]

Try to power the device from battery source and then take measures 200+mV are excessively high.

I'm referring to ripple not noise. I didn't have any noise contamination when I did the test, I also source the device from battery pack

[Aldo22]

Try to power the device from battery source and then take measures 200+mV are excessively high. I had one and the ripple values were around 28mv from battery source.

And if you supply it with 30V you won't get 30V at output mine did 28.6V

Thank you.
I don't have one (yet), I was just wondering if I should buy one for applications where “low noise” is an issue. I already have a "high noise" PSU. 
Not completely convinced yet as it obviously depends on the quality of the input.
Step-up converter would have been nice too.

[Evi]

New-New
https://banggood.com/DPS100-DC-Power-Supply-2_4-inch-HD-Screen-100W-Output-Type-C-DC-Input-Adjustable-Voltage-and-Current-10-Preset-Outputs-p-2021225.html?

[ptluis]

Try to power the device from battery source and then take measures 200+mV are excessively high. I had one and the ripple values were around 28mv from battery source.

And if you supply it with 30V you won't get 30V at output mine did 28.6V

Thank you.
I don't have one (yet), I was just wondering if I should buy one for applications where “low noise” is an issue. I already have a "high noise" PSU. 
Not completely convinced yet as it obviously depends on the quality of the input.
Step-up converter would have been nice too.

For low noise I always use battery as source and in cases were sensors with output up to 100mV always use battery as source without using smps or dc-dc converters only analog.

For lower voltage DUT you should always choose a ps that allow you to source it from battery pack , that's why I'm converting all my equipment to portable including Scopes, sig gen, etc, etc

You save alot of headache's

[ArdWar]

What topology is it anyway? I'd expect it to have linear post regulation (if only because you don't normally do constant current using switcher directly). But those reported ripple/noise performance are unconvincing...

[Aldo22]

For low noise I always use battery as source and in cases were sensors with output up to 100mV always use battery as source without using smps or dc-dc converters only analog.

For lower voltage DUT you should always choose a ps that allow you to source it from battery pack , that's why I'm converting all my equipment to portable including Scopes, sig gen, etc, etc

You save alot of headache's

A battery is certainly very good, but last week I made a power supply from an old Christmas tree transformer 12VA AC, 4 x 1N5399, a few capacitors and an L7812CV (without knowing what I was doing) and it is almost as "low-noise" as a battery.
I was amazed. 

I could actually use this as an input for the Fnirsi.

[ptluis]

For low noise I always use battery as source and in cases were sensors with output up to 100mV always use battery as source without using smps or dc-dc converters only analog.

For lower voltage DUT you should always choose a ps that allow you to source it from battery pack , that's why I'm converting all my equipment to portable including Scopes, sig gen, etc, etc

You save alot of headache's

A battery is certainly very good, but last week I made a power supply from an old Christmas tree transformer 12VA AC, 4 x 1N5399, a few capacitors and an L7812CV (without knowing what I was doing) and it is almost as "low-noise" as a battery.
I was amazed. 

I could actually use this as an input for the Fnirsi.

That's a nice way to learn and build a PS, with a decent heatsink that 7812 is able to supply 1A without any problem, with low ripple. The spikes I see I bet they come from your scope PS

[Aldo22]

The spikes I see I bet they come from your scope PS

I don't know where they come from. They are "in the air". 
I see a similar amount of noise even when I measure the battery pack.
In any case, this home-made PSU has almost no high-frequency noise.

EDIT: When I measure with the probes, I hardly see any spikes. The BNC cable shows much more noise.

[Fungus]

What's shown here is noise, not ripple. Noise like that doesn't normally come from a switching supply, it's external.

[ptluis]

The technique I use to measure PS ripple it's a kind of "special cable" that one side connects to the output of the power supply under test and on the other side (with the ground clip removed) I insert the probe on a soldered ground spring, the tip connects to a golden point on the pcb. 2 capacitors in parallel are added into the side where the probe connects. The two wires of this cable are twisted.

Aldo22 if you want to try this, beware with the capacitors operating voltage, the higher the better for safety reasons. You don't want to connect a 16V capacitor into a 60V PS 

Edit: Don't forget the polarity of the 47uF electrolytic capacitor! minus connects to the black wire!

This video shows how I do it:




This video also shows differences in different techniques, but I prefer the previous for it's flexibility to allow connecting different outputs connectors without much effort by using this "special cable"

[Aldo22]

@ptluis: Thank you!
OK, I've plugged in the soldering iron. 

What do you think of this construction? (Attached picture)
Since I have a probe adapter, I thought it would be easier this way.

What scope settings are you measuring at?
Sec/Div, BW Limiter, Acquire Method etc...

[ptluis]

@ptluis: Thank you!
OK, I've plugged in the soldering iron. 

What do you think of this construction? (Attached picture)
Since I have a probe adapter, I thought it would be easier this way.

What scope settings are you measuring at?
Sec/Div, BW Limiter, Acquire Method etc...

Don't forget to split the cable and twist the wires, don't leave them parallel to each other. Certify that insulation is in good condition to avoid shorts.
Normally I press Auto, manual only to zoom in the results or in case Auto fails to show proper results
AC coupling

Edit: if you get to much noise try the spring approach

[Aldo22]

Don't forget to split the cable and twist the wires, don't leave them parallel to each other. Certify that insulation is in good condition to avoid shorts.
Normally I press Auto, manual only to zoom in the results or in case Auto fails to show proper results
AC coupling

Edit: if you get to much noise try the spring approach

OK, I forgot to twist the wires. It's done now. 

It may depend on the scope, but for me “Auto” simply sets DC to show the 12V. But I need AC with 5mV or 2mV/div

It does make a difference whether I set “Peak Detect” or “Average” etc. on the scope. Also the Sec/Div.

In the attached pictures you can see my self-made PSU above and the (noisy) PDS-3010G below, both without load @12V.
Settings: AC | Peak Detect | No BW-Limitation | 200us/Div | 5mV/Div.

[ptluis]

Don't forget to split the cable and twist the wires, don't leave them parallel to each other. Certify that insulation is in good condition to avoid shorts.
Normally I press Auto, manual only to zoom in the results or in case Auto fails to show proper results
AC coupling

Edit: if you get to much noise try the spring approach

OK, I forgot to twist the wires. It's done now. 

It may depend on the scope, but for me “Auto” simply sets DC to show the 12V. But I need AC with 5mV or 2mV/div

It does make a difference whether I set “Peak Detect” or “Average” etc. on the scope. Also the Sec/Div.

In the attached pictures you can see my self-made PSU above and the (noisy) PDS-3010G below, both without load @12V.
Settings: AC | Peak Detect | No BW-Limitation | 200us/Div | 5mV/Div.

As you can see with the 2 capacitors and the twist cable approach you got cleaner results.

Did you tried RISE instead of peak detect? I think rise will be better for manual trigger fine tuning and to analyze ripple I don't know if your scope allows manual setting 1mV/div or lower so that you get a better view of the results, but of course the lower you go the more you amplify external contamination.

Btw from my understanding peak detect will be better to analyze switching spikes and not so good for ripple, the experts correct me if I'm wrong.

[Aldo22]

Did you tried RISE instead of peak detect?

Hi

I don't know what RISE is.
My cheap scope has the acq. modes: Normal - Hi-Res - Peak - Average.

Thank you.