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Old 06-01-2019, 12:35 PM   #41
Dannyx
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Thumbs up Re: DPS5020 dual power supply build

Thank you redwire for the schematic. We'll stick with this I think.

I need to scrounge up some Y caps (in parallel with the 1 meg resistors), though I believe they're misrepresented in the schematic as polarized ones.

Also, what diode should go on the output there ? I have a P600K on my current supply just tied between the output terminals as an after-thought, simply because that's the only type I had which had long enough leads to go from one binding post to the other
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Old 06-01-2019, 01:50 PM   #42
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Default Re: DPS5020 dual power supply build

diode should be schottky or very fast, with a nice safety area.
if it's schottky - the highest voltage you can find.
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Old 06-01-2019, 02:51 PM   #43
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Default Re: DPS5020 dual power supply build

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Originally Posted by Dannyx View Post
I'm the kind of guy who measures a dozen times, everything seems perfect, but when it's time to finally make the cut, I F it all up BIG TIME !
My father usually said: measure twice, cut once
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Old 06-01-2019, 02:58 PM   #44
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Default Re: DPS5020 dual power supply build

That's precisely what I said: I DO measure a dozen times and it all seems perfect, but somehow I STILL mess up the final cut and it all turns to sh!t
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Old 06-01-2019, 03:16 PM   #45
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Default Re: DPS5020 dual power supply build

templates & guides fixes that.
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Old 06-01-2019, 03:19 PM   #46
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Default Re: DPS5020 dual power supply build

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I need to scrounge up some Y caps (in parallel with the 1 meg resistors)
*ONLY* the hot side ground should be connected to earth ground (using either Y cap or RC)!
The analog ground (i.e. to the power transformer right) should not!

If you do connect them say goodbye to the 2 DPS working in series.
Even worst:
a human heavy electric static discharge on the analog terminal, i.e.: power supply analog ground output,
will make the main power electric differential to actuate and cut the power
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Old 06-01-2019, 03:24 PM   #47
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Default Re: DPS5020 dual power supply build

So you're saying I should not use the 1 meg resistors +caps ?

As for grounding the 230v input, the filter I showed in post #27 does that internally I believe.
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Old 06-01-2019, 03:55 PM   #48
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Default Re: DPS5020 dual power supply build

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So you're saying I should not use the 1 meg resistors +caps ?
As for grounding the 230v input, the filter I showed in post #27 does that internally I believe.
Yes that's it.
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Old 06-02-2019, 05:12 AM   #49
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Talking Re: DPS5020 dual power supply build

THIS popped up in my suggested articles on Ali today...I think it's starting to enter the realm of ridiculous for such an application Also, I think inrush of that thing would.....kill !
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Old 06-02-2019, 07:59 PM   #50
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Default Re: DPS5020 dual power supply build

It's good to have a reverse-diode across each output. P600 is good.
If you put the power supplies in series for more voltage, but something goes wrong (overload) the weaker PSU gets forced reverse voltage on its output.
The other reason is if you connect a battery backwards (smoke!) or connect an inductive load like motor, car coil etc there would be -ve voltage spikes.

Not having a 1MEG and Y-cap I disagree with megaraider, although I'm not clear what "hot side ground" and "analog ground" are.
For sure you don't want stray leakage currents lifting up the DPS voltages floating, so you need a path to earth ground. Prove it by measuring the AC leakage voltage and current (to PE, or between channels) without any 1MEG 10nF kind of thing. Or look at it with a scope.

I've always drawn non-polarized capacitors with a curved plate.
Old film caps have polarity as an "outside foil wrap", which you want connected to GND for shielding or to the output of a stage. This is a very old reason for the curved (-) plate (stripe mark) on a non-polarized film cap.
https://www.youtube.com/watch?v=BnR_DLd1PDI
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Last edited by redwire; 06-02-2019 at 08:01 PM..
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Old 06-02-2019, 11:42 PM   #51
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Thumbs up Re: DPS5020 dual power supply build

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Not having a 1MEG and Y-cap I disagree with megaraider, although I'm not clear what "hot side ground" and "analog ground" are.
I believe he's referring to the primary of the transformer (hot) and the secondary of the transformer ("analog") respectively, though I would like a confirmation indeed.
Sure sounds industry-standard to have a y-cap between your regulated ("cold") output and chassis (earth) GND....true, SMPSs are not designed with series-connection in mind, so I'm not sure how well the concept would transfer to our build here.
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Old 06-03-2019, 01:07 AM   #52
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Default Re: DPS5020 dual power supply build

Does this bother anyone? Imagine looking at it every day.... every day...
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Old 06-03-2019, 03:04 AM   #53
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Default Re: DPS5020 dual power supply build

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Does this bother anyone? Imagine looking at it every day.... every day...
Other than the DPS being ever so slightly crooked, it's decent
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Old 06-04-2019, 03:11 PM   #54
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Default Re: DPS5020 dual power supply build

Quote:
Originally Posted by Dannyx View Post
I believe he's referring to the primary of the transformer (hot) and the secondary of the transformer ("analog") respectively, though I would like a confirmation indeed.
Yes.
Quote:
Originally Posted by Dannyx View Post
Sure sounds industry-standard to have a y-cap between your regulated ("cold") output and chassis (earth) GND....true, SMPSs are not designed with series-connection in mind, so I'm not sure how well the concept would transfer to our build here.
Being a consumer and industry standard itís also applied in electronic lab equipment (mainly due to EMI test compliant), but with a big twist:
With the electronic lab equipment design engineer wariness of demand for flexibility in lab environment the connection from PE to ground is done only to bypass the compliant tests.
Therefore if any qualified experienced user needs to break it itís easily spotted and undoable, i.e. PE to analog connection only (PE to chassis and to cold ground remains connected).
See schematic for the KSGER 96W 24V 5A Electric Power Supply Unit in this post
Note the remark: ďSkinny trace for PE GNDĒ
Why skinny? Good example for the above mentioned isnít it?
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Old 06-04-2019, 03:14 PM   #55
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Default Re: DPS5020 dual power supply build

Btw, imo youríre overdoing the filter stage leading me to believe you might have forgot the overall picture.
Voltage ripple before the DPS5020 stage is not a concern, but the inrush current value is!

Why isnít ripple a concern at that stage? Because that job is up to the next stage: the DPS5020 module.

The only thing you must ensure is that the input voltage never falls below the minimum threshold at maximum output power set (highest voltage and current values).
Within the expected ripple frequencies 100Hz (120Hz USA) it can be feed even with a saw tooth wave for that matter, because the DPS5020 module has a feedback sample frequency in the tens of KHz at least.
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Old 06-05-2019, 03:12 PM   #56
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Talking Re: DPS5020 dual power supply build

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Btw, imo youríre overdoing the filter stage.
Yeah you are probably right.
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Old 06-05-2019, 06:30 PM   #57
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Default Re: DPS5020 dual power supply build

maybe update your schematic and see if everyone likes.
The small capacitors I'm suggesting are not for EMI or compliance, but are to swamp the power transformer's winding capacitance.
You can measure it, pri-sec, sec-core (with windings shorted) and see how much it is.
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Old 06-06-2019, 04:53 AM   #58
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Default Re: DPS5020 dual power supply build

what are the transformers, cubes or toroids??
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Old 06-06-2019, 08:49 AM   #59
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Default Re: DPS5020 dual power supply build

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what are the transformers, cubes or toroids??
See post no. 8: they're laminated ("E-I") UPS transformers, not toroids.
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Old 06-10-2019, 02:21 AM   #60
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Question Re: DPS5020 dual power supply build

Quote:
Originally Posted by redwire View Post
The small capacitors I'm suggesting are not for EMI or compliance, but are to swamp the power transformer's winding capacitance.
You can measure it, pri-sec, sec-core (with windings shorted) and see how much it is.
How do you do this ? Haven't done it before. A capacitance meter with one probe on the shorted windings of the primary and the other probe on the shorted secondary windings ? Worth a try I guess...
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