An update on the Rigol DP832 lab power supply fix.
+1An update on the Rigol DP832 lab power supply fix.
IMO, :palm:
"Precision" ? Where? This design doesn't have proper sense terminals. As you've just demonstrated in the video, it's easy to lose 20mV down a few cm of wire when you start pushing current through it - that's twice the claimed basic resolution! It makes a mockery of the 90 bucks you paid to check that the 1mV software switch worked.
Every "multiple output" PS I've ever used has had completely independent/isolated returns ("the black binding post") such that the outputs could be wired in series.
For V3.0, fix the returns, and make the "5V" output adjustable and/or with presets (1.8V, 3.3V, etc.)
It's not uncommon at all to have supplies with a shared common output... It's a design/cost tradeoff.
The 5V output is adjustable.
Is there a cap missing on the new board?
With that current sensing their claim to a precision power supply is just hogwash.
With that current sensing their claim to a precision power supply is just hogwash.
Only for the usage case demonstrated. Otherwise it is a precision supply and meets its spec.
So in the 4 possible connection usage cases:
1) Single supply = meets precision spec
2) Dual isolated supply = meets precision spec
3) Dual isolated + 3rd channel (separate return grounding) = meets precision spec
4) Dual isolated + 3rd channel (shared return ground) = may not meet it's precision spec (depending upon output current)
Regarding that current sensing in the ground connection, shame on Rigol. Every serious article about power supply design tells you not to do it on the ground connection, unless the channel is completely isolated. With that current sensing their claim to a precision power supply is just hogwash.
Except putting the sense resistors low here has caused no problem, and nor would I expect it to. It'd work just fine if they strongly tied the two common terminals together, and just had one voltage sense wire sampling the potential at this "one true ground".
You are going soft Dave :), this is a lazy Claytons fix. As you said the correct solution would have been to reduce the voltage coming from the tranny. I guess Rigol already have a stock of trannies they need to shift. IMHO there is still far too much power going into heating the lab. As you would say, you can fly to the moon on a few hundred milliwatts. Have you considered adding a contra winding the secondary to reduce the tranny output voltage? Yes it's a dirty hack but an effective hack all the same.
You are going soft Dave :), this is a lazy Claytons fix. As you said the correct solution would have been to reduce the voltage coming from the tranny.
IMHO there is still far too much power going into heating the lab.
Have you considered adding a contra winding the secondary to reduce the tranny output voltage?
Hmm considering that so far all people have got black anodized heatsinks on their PSU, would it be possible that they just put in custom (much larger) heatsink just for you?
Don't ask me how, but I've got a couple pictures of Rigol's newest power supply, code named the DP92:I would have guessed they would just use some water cooling on that next time. :scared:
What really grinds my gears is all that output capacitance. Imagine if you had something that you were running on constant current at 10mA, then you disconnect it and connect it again, and all that cap just entirely discharges into the load... :--Use a constant current source then.
Who would have guessed that they fail to calculate the size requirement for that heatsink, twice.
yea well. SMPS PSU have their use. But they also have downsides, so depending on your application you have to choose. I know a liniar is not very efficient, but I don't care, I want some thing that is 100% noise free.
yea well. SMPS PSU have their use. But they also have downsides, so depending on your application you have to choose. I know a liniar is not very efficient, but I don't care, I want some thing that is 100% noise free.
But then, the whole thing must be considered as a whole, not just the regulator that powers the processor. There is a i.MX processor running on 100's of MHz along with an internal switching regulator, DDR memory and wide parallel bus going into LCD, I'd think that is already quite far from 100% noise free analog stuff anyway. Small switch-mode regulator doesn't change EMI properties that much anymore. It would be a different thing if there weren't any digital electronics in that thing.
Regards,
Janne
Yes, it's pretty silly.
The first time they realised it themselves (or had someone else find it?) and changed from the small one to the larger black anodised one. Then due to my video they doubled the size again with the same footprint.
Yes, it's pretty silly.
The first time they realised it themselves (or had someone else find it?) and changed from the small one to the larger black anodised one. Then due to my video they doubled the size again with the same footprint.
Sorry if I missed this answer somewhere. I did read all of this thread.
Is the larger black anodised one still ok? I measured 63C at 25C ambient on the side of the heat sink with the fins. It was powered on for about 20 minutes. I should also mention it was with the case on, I stuck my thermocouple through the holes.
Thanks!
-Matt
I checked my replacement DP832A and it still has the power on voltage spikes. My question to the
Forum is, do your other power supplies also exhibit power on spikes? I own a Hameg triple power supply that also shows power on spikes.
Too many issues on this thing, don't worth buying.
Too many issues on this thing, don't worth buying.
I don't think that's true at all. Every bit of test gear will have something that any given user won't like.
Just be aware of the issues your equipment has and you'll be fine.
I'll be buying one of these soon. I am aware of the issues, and given the price and features, this is a pretty awesome power supply.
Any news on the reset and the power-on (voltage spikes while output is disabled) issues?
Any news on the reset and the power-on (voltage spikes while output is disabled) issues?
I'm also curious about the reset issue... Has it been fixed with the new revision?
Any other option with similar features and maximum 32cm deep?
I´m looking for a new PS for my bench and, in general, I liked this DP832. Obviously those circular keys are ridiculous, but the features and the display looks very nice. But 42 cm deep is too much for my bench. Why so deep?
Two questions:
Any other option with similar features and maximum 32cm deep?
What is the model or where to buy this temperature sensor Dave uses in his Fluke? I have one Fluke 187 and would be nice to have this probe.
Thank you!
I´m looking for a new PS for my bench and, in general, I liked this DP832. Obviously those circular keys are ridiculous, but the features and the display looks very nice. But 42 cm deep is too much for my bench. Why so deep?
Two questions:
Any other option with similar features and maximum 32cm deep?
[..]
That is a 2 edged sword, what about full current transient response without the output cap? Some old hp supplies have the output cap connected thru rear terminal straps so you can unstrap the cap when you don't want it.
why are you calibrating a new supply? don't dink with calibration unless you know what you are doing and you have the proper equipment. |O
somewhere I believe there are calibration instructions for the dp832. if you don't have them, find them, and if you can get an inexpensive voltage standard on eBay (they can be had) you might be able to make something happen with it, such as finding out how far your 87V is out.
try ch3, too.followup... First, I'm not very smart :-\, and second, you are correct, current limit on ch1 is off by 2-3 ma. I set the limit to 1mA, it actually limits to 3-4ma. I suppose that's within the spec for that. Don't know if it has anything to do with what I did. Thanks for the feedback.
besides, if your calibration is out, you can't really trust anything about it until it is calibrated again. it might think it is sending 1ma into ch1 but actually be sending 3ma. if cal is out, you cannot trust those times.
Hi all,Have you seen the new Rigol 2014 Calibration Guide attached here?
Sorry for repeat my problem, but i lost two channels (2 and 3) of my dp832, after that i install the new top board (version 2.01).
I can calibrate just the channel 1 and him works fine, i have sure that follow all steps recommended by rigol correctly.
I updated the firmware and bootloader of version 1.03 to 1.09.
Somebody have any idea to help me solve this problem ?
Thanks.