Suitable USB-C powerbank for Rigol DHO800/900 series - Page 1
Forum section: electronics / testgear

author: Houseman
author_rank: Regular Contributor
timestamp: February 07, 2024, 04:36:07 pm
content: Hi folks.Time to get a return of the bucks invested for my Rigol DHO that has been claimed been powered by a powerbank..As also claimed in this video:Need to do some low noise tests and the 230V wall socket is too noisy.Apart from the fact that also the powerbank will inject some noise into the scope via internal circuitry I cannot find a suitable powerbank to make my tests.The PD specs arrives at maximum 25W at 12V, nothing needed for our greedy beasts... i have a beefy 23800mAh PD 65W Power Bank Yeah but at specs USB C(In-Out): 5V-3A 9V-3A 12V-3A 15V-3A 20V-3.25A (Max 65W). that does not even turn the fan on.So any help would be very appreciated for any link or hint.The are some Power Bank, 25000mAh 100W Fast Charging Powerbank. should I trust them?And after all... does it make sense for You in terms of noise? best regards and thanks

author: coromonadalix
author_rank: Super Contributor
timestamp: February 07, 2024, 04:52:18 pm
content: some powerbank will not inject noises if you have a good cell count in it, a good pack may or will have some BMS, but normally you're not supposed to get any noises out of them if they don't up or down the voltage(s)i do have one with 16850 cells from Ali non branded... but very clean on the output ?? it's a 10 ampgosh I hate the number gimmick they use 10000 ma, 25000 ma, i hope to see 1000000 ma bank loll

author: ebastler
author_rank: Super Contributor
timestamp: February 07, 2024, 05:04:19 pm
content: There already is a recent thread about this topic:https://www.eevblog.com/forum/testgear/powerbanks-tested-with-dho800900/Edit: How do you know that the noise comes in via the power line?

author: Houseman
author_rank: Regular Contributor
timestamp: February 07, 2024, 05:06:30 pm
content: Ah ok I understand that's a good starting point.You mean placing a 3S (something parallel) 18560 and a simple BMS will do the job rather than investing in some ready made branded Power Delivery circuitry?Thank You

author: Houseman
author_rank: Regular Contributor
timestamp: February 07, 2024, 05:08:32 pm
content: Quote from: ebastler on February 07, 2024, 05:04:19 pmThanks for the link.By simply switching my LED monitor OFF , the noise floor will be reduced by 20mVpp!!!!

author: Houseman
author_rank: Regular Contributor
timestamp: February 07, 2024, 05:14:02 pm
content: So maybe an old black-heavy sealed 12V 7A used inside UPS will do the job?

author: ebastler
author_rank: Super Contributor
timestamp: February 07, 2024, 06:18:11 pm
content: If you are not after portability but want to avoid any switching noise, why not? It's a 7 Amp*hour battery, not 7 A, and when discharged at 4 A it will give you less than 7 Ah capacity. But should certainly last you more than an hour.I am not 100% convinced by your cause-of-noise analysis. Can you be sure it's wire-bound immission rather than radiated? Also, if the immissions are indeed coming wire-bound from your monitor -- why not switch that off while you are taking the measurements?I believe we had someone comparing noise between a mains-powered DHO800 and one powered from a battery, and there was no significant difference. The power supply of the DHO800 itself is pretty decent. (Excluding the 12V fixed supply shipped with the pilot models last summer.)EDIT: Assuming that you observed the noise while using probes, have you tried using the ground springs instead of the short ground leads?

author: alm
author_rank: Super Contributor
timestamp: February 07, 2024, 06:45:50 pm
content: Did you try if connecting the scope to earth via a separate wire helps? I believe the manual advices this. It's also a good idea for safety if you work with any dangerous voltages, since it prevents the exposed metal bits on the scope to be at elevated voltages.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: February 07, 2024, 07:28:50 pm
content: I got these a year or two back to check the different input stages before a given product, as a lot of my tools are centered around portability and the use of powerbanks, and the AC PSU to some of my gear seemed quite noisy.

author: Pinkus
author_rank: Frequent Contributor
timestamp: February 08, 2024, 11:33:08 am
content: Note for the post above: Search at Aliexpress for "ripple test board". The set (USB A und USB C) costs about $30.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: February 08, 2024, 03:52:43 pm
content: Quote from: Pinkus on February 08, 2024, 11:33:08 amDoesn't do much at my end, ..https://aliexpress.com/w/wholesale-ripple-test-board.html?spm=a2g0o.productlist.search.0but then again quite a lot of listings are behind-region lock in 2024 on Aliexpress, so could be that you see listings I dont, not to mention these adapters are quite old, so you can't take for granted they are still for sale.Maybe you could share an active purchase link, as I cant.. hence none in stock for quite a while.In regards to powerbanks and certain Rigol products, worth noting they seem to consume a roundtrip to the moon & back in their breathing standby-mode atleast on this unit I got, that aint a DHxxx but a signal gen [DG800PRO) that uses the same form-factor, but it's a new product not released yet in the west, so could also be down to a far from optimal firmware.above 6 watts in a closed with power-status (FY6900 around 0.4w & DG800PRO 6watt)https://i.imgur.com/wtk7uhu.mp4

author: Houseman
author_rank: Regular Contributor
timestamp: February 09, 2024, 06:55:55 am
content: Is it a BNC connector connected to the VUSB and ground via a resistor and a capacitor?How do you use it?Thank you

author: flaotte
author_rank: Contributor
timestamp: March 11, 2024, 10:17:57 am
content: I just want to double check.If oscilloscope is powered from power bank, is it save to measure mains/mains coupled wires?300V insulation means single phase at a time?

author: ebastler
author_rank: Super Contributor
timestamp: March 11, 2024, 10:25:53 am
content: Quote from: flaotte on March 11, 2024, 10:17:57 amYou run less danger of damaging thescopethat way -- since it is not grounded, you will not cause a short circuit if you connect the probe's ground clip to a high potential.But you much increase the danger of damagingyourself! While you will not notice a problem with the scope's functionality if you make that connection, it will connect parts of the scope which you can touch -- nost notably the BNC connectors, and the shells of any BNC plugs you connect to them -- to that high potential. You can potentially kill yourself by tuoching them.So, please don't use the scope to measure mains voltage that way!