Author Topic: EEZ Bench Box 3 (BB3)  (Read 58679 times)

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Offline AlanS

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Re: EEZ Bench Box 3 (BB3)
« Reply #275 on: March 22, 2020, 06:27:20 am »
Sorry Denis I was being a smart arse. The BB3 is getting close to doing all of our jobs for us. :palm:
 

Offline wizard69

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Re: EEZ Bench Box 3 (BB3)
« Reply #276 on: March 24, 2020, 02:03:16 am »
With respect to MircoPython is there a physical RS232 port available?    I didn't notice if one existed and if MicroPython even supports such for the controller board.   The idea of course is to be able to hook up to the most basic of process controller, most of which seem to do RS232 comms.
 

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #277 on: March 24, 2020, 06:44:36 am »
There is not RS232 port per se. But UART (TTL) port is exposed on the front panel (Din1 and Dout2 pins) and Virtual COM via USB is supported. It is important to understand that MicroPython is not implemented here as "core engine" but it's just one of the process under control of FreeRTOS. Therefore you are not able to access directly with MP any hardware resource, and cannot, let's say, compromise core processes. MP has on its disposal "high-level" functions that are accessible with SCPI commands. For example, you cannot go with MP to DAC on the Ch1 power module and set its value to 1.25 V to have 20 V on the power output, but you can use scpi("VOLT 20") to do the job. So, the MP is added as a scripting tool in the first place, that one can easily automate various tasks. Those who are interested can find existing examples on the following link: https://github.com/eez-open/modular-psu-firmware/tree/master/scripts
 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #278 on: April 12, 2020, 11:16:39 am »
A short introduction to newly added power output ramp and delay feature.

 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #279 on: April 14, 2020, 07:20:29 am »
The prototypes of the three new modules (PREL6, SMX46 and MIO168) have been assembled and ready for integration into BB3.

All modules will be presented and accessible via a local touchscreen and supported through SCPI and MQTT and managed using MicroPython scripts. The first practical scenario for their use will be to automate testing of assembled BB3 units once we have passed the required certification tests.





 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #280 on: April 14, 2020, 07:22:53 am »
Front panel view with new module:


 
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Online jbb

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Re: EEZ Bench Box 3 (BB3)
« Reply #281 on: April 14, 2020, 08:15:02 am »
It’s so great to see these modules coming out. And using these parts to test your own products is really showing some confidence... and should find all kinds of little bugs.

I know what they’re all for, but that seems like a lot of analog switch ICs :-). I’m sure people will find the V / I / NTC input ranges helpful.
 
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Offline jan28

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Re: EEZ Bench Box 3 (BB3)
« Reply #282 on: April 14, 2020, 04:31:36 pm »
A short introduction to newly added power output ramp and delay feature.



First of all: Nice feature.

I played around with the trigger, list and ramp features in the simulator and am wondering: Why is ramp a separate function instead of a property of the list implementation?
I will try to explain using SCPI commands. If there would be an command like:

[SOURce[<n>]]:LIST:TYPE   {ramptype}[, ...]  where ramptype = 0 mean step, 1 = linear ramp, 2 = exponential ramp, ... = use imagination...

This would make:
-[SOURce[<n>]]:CURRent:MODE STEP, CURRent:TRIGgered and CURRent:RAMP:DURation {<duration>} (and voltage equivalents) obsolete
- programmability more flexible because a list can generate ramps arbitrary up/down steps, etc.
- UI could stil have a menu to program a STEP in a simple way: This would just create a LIST with the right properties. The user can even edit the list afterwards to add steps (in that case going back to STEP menu would clear the list after a warning/conformation)
- The list edit menu would also need a type selection (icon?) for voltage and current. I think this would fit.

Makes any sense?
 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #283 on: April 15, 2020, 07:14:00 am »
Yes, it makes sense what you said. What we have now may have happened to others as things gradually added. I tried to add a similar set of commands that can be found with e.g. Keysight or R&S. What is count on the first place is user experience, and that is of course a question of taste, habit and experience. For advanced user it will be more interesting to have everything on single place as you suggested. For beginners, setting up just a turn-on ramp&delay might be sufficient.
What we are missing is more flexible way for adding ramps (triangle) in program list, the same stands for e.g. sine wave generation. For that I'd like to add [SOURce[<n>]]:ARB subsystem, again to be more "compatible" with big guys. Perhaps [SOURce[<n>]]:LIST:TYPE is also implemented by others, if you have any reference please let me know.

Offline jan28

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Re: EEZ Bench Box 3 (BB3)
« Reply #284 on: April 15, 2020, 10:00:23 am »
I didn't look to the big guys, just made it up.  ;D

I did some digging in manuals: Keysight doesn't have a property like this in there list function in the models I looked up. The R&S NGP800 has an 'interpolate' option in there implementation of a list which they call ARB. It's not exactly defined what interpolation it does, but looks like lineair interpolation, which I called lineair ramp before. On there product page they have a screenshot of it (under Arbitrary Function): https://www.rohde-schwarz.com/nl/product/ngp800-productstartpage_63493-670592.html

The word Interpolate/Interpolation is a much more specific description of the functionality compared to the TYPE I made up.

The R&S SCPI implementation is not so nice (to my taste), because you quickly get into some kind of comma-counting-hell  >:D and it doesn't allow for adding options/features later on in a backwards compatible way:
ARB:BLOC:DATA 1,1,1,1,0,2,2,2,1,1,3,3,1,0  (its a repeat of volt, current,time,interpolate)

BB3 equivalent:
LIST:VOLT  1,2,3
LIST:CUR   1,2,3
LIST:DWEL 1,1,1
LIST:INTerpolate 0,1,0  (new, instead of TYPE, 0= step, 1= interpolate)

Both sets of commands do the same:
- 1V,1A for 1 sec as a step
- rising from 1V,1A to 2V,2A in 1 sec   (this is the function we're talking about)
- 3V,3A for 1 sec as a step

I agree that more complex ways of interpolation (e.g. exponential) might be better handled with the ARB subsystem. Just adding the interpolation makes the list function very powerful (in my opinion).
 
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Offline Rerouter

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Re: EEZ Bench Box 3 (BB3)
« Reply #285 on: April 15, 2020, 10:29:45 am »
That method while possibly needing a little polish would leave room for odd ramps, e.g. a sine wave could be done by adding type classes for the 3 sine segments,  step gets you square like waves, interpolate gets you ramps, and other modes gets you sine and other,
Sine I see as being 3 main options, either crest / peak with the slow start and then fast change,
fast change to slow crest / peak
or from crest to peak or vice versa as a half sine wave.

If you wanted to you might then later make use of that chunk of code to generate some of the simple shapes via UI.

This way a sine wave would just be an arb table of the min / max voltage and the smooth type with the frequency being the inverse of the interpolation time.

Edit: and things like simulating a rectifier output would just be a fast start segment + a ramp down in a cycle.
Edit2: while probably not the easiest thing, allowing things like % as an input for the values would make things a bit more powerful, so e.g. adjusting the maximum amplitude, the min being set at 60% then tracks along at 60% of that start value, or vice versa if the end was a % and the start a fixed value. this would be more for UI than SCPI, but I'm dreaming.
Edit3: or relative values, e.g. *-2V for 2V less than the start value, probably again for UI.
« Last Edit: April 15, 2020, 10:51:35 am by Rerouter »
 

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #286 on: April 18, 2020, 07:30:44 am »
@Jan28, @Rerouter thanks for additional comments and suggestions. I have opened a new ticket (#22) in which I have added your suggestions that can be taken into account in the new firmware revision. I'll keep you posted on the progress.
 
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Offline prasimix

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EEZ BB3 User manual
« Reply #287 on: April 18, 2020, 01:47:20 pm »
EEZ BB3 User manual on English and German is now available online: https://www.envox.hr/eez/eez-bench-box-3/bb3-user-manual/1-introduction.html
 
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Offline jan28

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Re: EEZ Bench Box 3 (BB3)
« Reply #288 on: April 21, 2020, 08:40:35 pm »
Looks nice and clear. Can't wait to actually assemble mine.

After Figure 26 (insert SD card) you might want to add an instruction to turn the device off and remove the power cord before continuing with the power modules. Just to be sure.
 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #289 on: April 21, 2020, 09:36:31 pm »
Good point! I'll add that.

Offline MaxZ

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Re: EEZ Bench Box 3 (BB3)
« Reply #290 on: April 28, 2020, 05:57:17 pm »
Hi,


I love the concepts of your open source power supply! Since my lab supply blew up today and I need one I am curious if you have any idea how big the backlog is. Or in other words: when would I get one if I order now  ;D

Second question: I'm working with royer oscillators and other inverter topologies. My last supply didn't like that very much (not a high end one, but still) and I've heard this could cause problems with other, better supplies. Do you know if your supply is robust enough? Can it handle spikes of HF ripple on the output?


Thank you (for all of your work and for reading my questions ;) )
Max
 

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #291 on: April 28, 2020, 06:59:01 pm »
Hi,


I love the concepts of your open source power supply! Since my lab supply blew up today and I need one I am curious if you have any idea how big the backlog is. Or in other words: when would I get one if I order now  ;D

Second question: I'm working with royer oscillators and other inverter topologies. My last supply didn't like that very much (not a high end one, but still) and I've heard this could cause problems with other, better supplies. Do you know if your supply is robust enough? Can it handle spikes of HF ripple on the output?


Thank you (for all of your work and for reading my questions ;) )
Max

Hi Max, we're going to ship 50+ more units to CS/Mouser together with campaign fulfillment. Therefore if you order it now, I don't see a reason not to receive it in the same time as campaign backers.

Powering mentioned kind of devices could be a problem and is not easy to cover different scenarios when connected load/device works under different input voltage, switching frequency, has connected different load to its output, etc. I have an oscillator that is used to generate 10 kV+ and producing plasma beam/arc. It is so nasty that once it was almost completely destroyed my previous mobile phone that was more then a meter away. When powered from H24005 from my previous project it has a power to wipe off all content on the TFT display and occasionally even reset a whole unit. I tried the same scenario many months with BB3 and didn't seen similar effect (ok, the TFT display and MCU is different). I can try it once again, but that is no warranty that your or similar device do not generate problem to BB3.
« Last Edit: April 28, 2020, 09:49:38 pm by prasimix »
 
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Offline mcdanlj

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Re: EEZ Bench Box 3 (BB3)
« Reply #292 on: April 28, 2020, 11:38:53 pm »
I saw this from Kerry Wong:
http://www.kerrywong.com/2020/04/12/non-destructive-testing-of-fuses/

Seemed like the kind of thing that the python scripts would be useful for. ☺
 
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Offline danielbriggs

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Re: EEZ Bench Box 3 (BB3)
« Reply #293 on: April 29, 2020, 06:58:50 pm »
Does the DCM220 allow for using shrouded 4mm banana plugs?
 

Online jbb

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Re: EEZ Bench Box 3 (BB3)
« Reply #294 on: April 30, 2020, 12:36:02 am »
...I'm working with royer oscillators and other inverter topologies. My last supply didn't like that very much ... Do you know if your supply is robust enough?

I guess this depends on whether it's RF content (MHz+) getting in and messing things up or big swings in power flow due to converter ripple (kHz - MHz) messing up the regulation.

If it's the former, you could try clip on ferrite EMI filters.

If it's the latter, I've achieved some good results in the past with a crude method:
  • Use internal voltage sense, not 4 wire external sense
  • Put a shunt resistor directly across the bench supply output, drawing 1% to 5% of power supply current rating. This will get the output stage, drivers etc. conducting. Unfortunately power supply current reading will now have an offset. (If you let the resistor warm up to constant temperature the offset should be pretty stable, at least.)
  • Put a series resistor between the bench supply and load. I've used enough in the past to drop 1% to 5% of the supply voltage under expected load.  Unfortunately power supply voltage reading will now be wrong, and the offset will depend on load current.

 

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #295 on: April 30, 2020, 07:58:16 am »
Does the DCM220 allow for using shrouded 4mm banana plugs?

No, it does not.

Online jbb

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Re: EEZ Bench Box 3 (BB3)
« Reply #296 on: April 30, 2020, 08:18:24 am »
Someone (Cal Tech?) makes some converters which have a shrouded banana jack on one end and a standard banana plug on the other. There’s a little grub screw inside so that you can lock the banana plug into place.

Ooh, not what you’re looking for but Pomona 2894 (banana plug to binding post) could be handy.
 

Offline jan28

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Re: EEZ Bench Box 3 (BB3)
« Reply #297 on: April 30, 2020, 01:48:42 pm »
I'm thinking about https://spot.staubli.com/fileadmin/spot/24.0163_en.pdf for the DCM220. They're not very expensive about 2 euro's a piece.




 
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Offline danielbriggs

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Re: EEZ Bench Box 3 (BB3)
« Reply #298 on: April 30, 2020, 01:54:27 pm »
I'm thinking about https://spot.staubli.com/fileadmin/spot/24.0163_en.pdf for the DCM220. They're not very expensive about 2 euro's a piece.

That's an interesting solution (also good for other instruments I have here).

@Denis, is there any scope for the DCM220 to accept the same terminals as on the other modules that accept shrouded 4mm's? (Even if I drill out the panel slightly)

Have you got the part numbers for both connectors on either module to hand?
 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #299 on: April 30, 2020, 02:03:24 pm »
Hm, I didn't pay too much attention to the DCM220 because I saw it as an auxiliary power source from the beginning. To reduce costs, I also chose cheaper terminals. That turns out to not be the wisest decision :)
At the moment, I can only promise that in the next version, the DCM module will get the same terminals as the DCP module.

Part numbers can be found in BOMs: here and here.


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