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DC Load - I need some guidance

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mvno_subscriber:
Hi,

I'm looking to finally get an electronic DC load. Previously, I've used power resistors, but it's cumbersome. I then started researching and I realized that there were programmable loads with a great deal of features that would be very handy today, and others that would probably be great tomorrow.

Regardless of where I go, I find praise and criticism for both. There's always someone who finds them utterly useless, noisy, etc. My primary need is to test out both linear and switching power supplies, but battery testing and simulating noisy loads and how they affect other parts of a circuit is also very relevant.

I originally began looking at Rigol DL3021 and Sigilent SDL2021X-E. I thought I had decided on the SDL2021X-E, simply because the software seemed better, and it wasn't as noisy as the Rigol (I have a Rigol scope, and even though I love it, it drives me nuts sometimes).

Now, of course, as always, doubt sets in. And while perusing other loads at other dealers, I stumbled upon B&K Precision 8550, which for some reason seemed very attractive to me. It also boasted more features/better software, larger LCD and seemed more practical on the whole. Except for the backside, which has none of the connectivity of Rigol/Sigilent. I don't have any need for it now, as a USB stick with preprogrammed routines will work fine, but who knows.

Price wise of course, the 8550 is in a totally different bracket than SDL2021X-E. Forking out for the latter is still a large investment to me, but I'm also not foreign to spending bucks to get good stuff that will last and still prove useful 10-20 years on, as my projects and knowledge evolve.

Then, I read that B&K is simply ITech, only overpriced, and that's that. I know there are hundreds of threads like this, and I've tried my best to google around in the last couple of weeks, but right now I feel pretty stuck. Any advice or input would be greatly appreciated.

2N3055:

--- Quote from: mvno_subscriber on June 10, 2024, 04:56:25 pm ---Hi,

I'm looking to finally get an electronic DC load. Previously, I've used power resistors, but it's cumbersome. I then started researching and I realized that there were programmable loads with a great deal of features that would be very handy today, and others that would probably be great tomorrow.

Regardless of where I go, I find praise and criticism for both. There's always someone who finds them utterly useless, noisy, etc. My primary need is to test out both linear and switching power supplies, but battery testing and simulating noisy loads and how they affect other parts of a circuit is also very relevant.


--- End quote ---

You might be overcomplicating things.

General loads (all of the ones you mentioned are in that category) are very useful tools. But also limited.

They are useful for :

- static loading of voltage/current sources for purposes of thermal testing
- for testing/measuring battery capacity
- for testing of solar panels I/V curves
- for dynamic load testing where switch between two currents and look for load/unload response.
- for testing large LED

What you cannot do with them is using them as a load while performing any kind of frequency response analysis. Or use it as a load while measuring PSU noise and ripple.
They are also limited in speed of load change, not very good at low currents (because that is not what they were designed for.).

Honestly, all of the ones mentioned can do the job. I personally have Maynuo 9812 that have "LED mode" that changes control loop response. Unit is a bit old fashioned UI on the device. It has very powerful software for the PC though.

If I were you I would choose by price and ease of driving.

nctnico:

--- Quote from: mvno_subscriber on June 10, 2024, 04:56:25 pm ---Hi,

I'm looking to finally get an electronic DC load. Previously, I've used power resistors, but it's cumbersome. I then started researching and I realized that there were programmable loads with a great deal of features that would be very handy today, and others that would probably be great tomorrow.

Regardless of where I go, I find praise and criticism for both. There's always someone who finds them utterly useless, noisy, etc. My primary need is to test out both linear and switching power supplies, but battery testing and simulating noisy loads and how they affect other parts of a circuit is also very relevant.

Now, of course, as always, doubt sets in. And while perusing other loads at other dealers, I stumbled upon B&K Precision 8550, which for some reason seemed very attractive to me. It also boasted more features/better software, larger LCD and seemed more practical on the whole.

--- End quote ---
The B&K Precision 8550 is a rebadged Tonghui DC load.

I have been looking at a DC load myself and settled on a Korad KEL2010 (after testing it thouroughly). After a fix to swap the fan and move the mains transformer away from the analog circuitry, the KEL2010 also works well for currents in the single digit mA range.

See these threads:
https://www.eevblog.com/forum/testgear/dc-load-korad-kel2010-or-tonghui-th8402a/msg4969006/
https://www.eevblog.com/forum/testgear/korad-kel2010-multicomp-mp710771-review/msg4975759/

mvno_subscriber:

--- Quote from: 2N3055 on June 10, 2024, 06:30:42 pm ---
What you cannot do with them is using them as a load while performing any kind of frequency response analysis. Or use it as a load while measuring PSU noise and ripple.
They are also limited in speed of load change, not very good at low currents (because that is not what they were designed for.).


--- End quote ---

This I don't quite understand -- when in transient mode, switching between currents, or in list mode, wouldn't that be useful for measuring PSU ripple and transient response? B&K has features specifically made to test DC power supplies as well (sweep mode, load regulation test).

Also, with regards to low currents - mA resolution are from 0.05mA to 1mA in CC mode, depending on model. In my world that's low current. Or am I not reading the specs correctly?

mvno_subscriber:

--- Quote from: nctnico on June 10, 2024, 07:10:19 pm ---The B&K Precision 8550 is a rebadged Tonghui DC load.

--- End quote ---

Not sure if that is meant as a bad thing or not, as far as I read in the threads you provided, Tonghui is seen as an ok brand. Buying Korad, Tonghui or Rigol from AliExpress is not any cheaper than buying RND, B&K or Rigol here at home, when considering shipping and taxes (except you don't get any proper warranty or support!).

When it comes to having to modify the unit in order to make it work properly; that's not for me. I need a device that works well, with good support and firmware upgrades.

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