Rigol DP832 vs DP831A (not 832A) and general +/- dc supply questions

[PaulHart]

I am interested in purchasing my first programmable bench power supply and I am particularly attached to the recently reviewed DP832 (EEVblog #509) for its price, functionality and low ripple/noise specifications.

The DP831A (not to be confused with the 832A) provides +30v and -30v rails instead of the two 30v rails of the DP832.

Is this of any consequence for powering split supply circuits like op amps and ACDs? How does using a +/- power supply differ from using two ‘positive’ channels in series with the connection between them used as a virtual ground? Also, is it possible to terminate the virtual ground of the supply to earth ground?

Thank you for any help and advice.

[tlu]

I'm also interested in the negative voltage usage as well. Can the dp832 do this with a virtual ground as mentioned?

[alm]

Yes, you can put two channels in series for +/- 30 V rails as long as they're isolated (they are in the DP832) and ground whatever point you find convenient. Grounding is not required, however. I haven't read the DP831A datasheet, but if they advertise +/- 30 V rails, then this most likely means these rails are not isolated but have a common terminal, similar to channel 2 & 3 in the DP832. This makes the supply less versatile.

[neslekkim]

I ordered an 832A, but got an 831A in the mail now...

I have reported back to the supplier that I got wrong model, but I'm wondering, is there any reason to redo the deal, and keep the 831A instead of the 832A? (to save the hassle of carrying this monster back to the postoffice.. )

There are more Amps on the 832A, which was the reason for ordering that instead of the 831A since the price is almost the same, but is there any other reason for choosing one over the other?

[Stupid Beard]

The most obvious difference is the way the channels are setup. I didn't look too closely at the other specs though.

831A has CH1 8V 5A, CH2 30V 2A and CH3 -30V 2A
832A has CH1 30V 3A, CH2 30V 3A and CH3 5V 3A

See http://www.rigolna.com/products/dc-power-supplies/dp800/dp831a/ and http://www.rigolna.com/products/dc-power-supplies/dp800/dp832a/

[Macbeth]

The 831 would probably be useful if you are working on a design with a seperate analog and digital section isolated from each other where the analog needs a split rail for the op-amps for example.

The 832 can do a split rail with its normally isolated 30V outputs connected in series (e.g. CH1+ connected to CH2-), but the 5V channel shares it's ground with CH2 so the digital side would no longer be isolated.

However the 832 has up to 60V at 3A available, and you can parallel the isolated outputs to get 6A at 30V. You can't parallel the +/-30V on the 831, so 2A max it is.

Also, I think the 832 is much more widely known and would probably be easier to sell on. It seems to have had quite a few firmware revisions and the heatsink fix. Also don't forget Riglol  I don't know about the 831.

If it's the suppliers fault then I would return it for replacement at their cost. If it's your cockup then find out how much return post is and decide if it's really worth pursuing.

[neslekkim]

Thanks for the replies, much helpful!

If it's the suppliers fault then I would return it for replacement at their cost. If it's your cockup then find out how much return post is and decide if it's really worth pursuing.

Luckily it's not my cockup, I checked the invoice I paid before they sent it, and modelnumber+serial number is different than on the model received.
I guess someone was stressing and put the shipmentpapers on wrong carton..

But now I know more so I think I swap to the one I wanted, I already have an 2x30v 1.5A psu, so It's better with an 3a, especially since I can use it in paralleled mode.
I saw that the front was easier on this regarding -30-gnd-+30, but I have read somewhere else that I also can configure the 832 the same way for that type of use (Bought an opamp training board from TI that i want to hook up, among other things.)

[Macbeth]

Ah, yes I have the same TI board but haven't had a chance to go through the course yet. I decided to be pro-active and download all its content because I don't want to be tied to the internet when watching the vids, or worse, find they have pulled the content when I finally get round to it! PITA downloading those vids I tell ya (had to mess about with Chrome dev mode).

Anyway, either PSU is good enough. One thing, you say you are getting the 831A vs the 832 (non A)?. You may want to keep hold of it as it's actually the one with all the extra features and sells for a few hundred dollars more!! Sell it as new and then buy an 832 (non A) which you enable the Riglol hack features with   Profit!

[neslekkim]

I ordered 832A, and got 831A..

[neslekkim]

yay, new psu on it's way.