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ea-ps_2084-03b [2015/05/26 17:41] – created kingkevinea-ps_2084-03b [2024/01/07 17:49] (current) – external edit 127.0.0.1
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   * wide voltage range (0-50 V)   * wide voltage range (0-50 V)
   * silent   * silent
-  * will an earth connection+  * have an earth connection
   * not expensive   * not expensive
   * not noname   * not noname
-  * most importantly: provide a communication interface+  * provide a communication interface (most important)
  
 I found and bought a used power supply on eBay for ~ 80 €. I found and bought a used power supply on eBay for ~ 80 €.
-And now I own an [[http://www.elektroautomatik.de/en/|Elektro-Automatik]] (EA) [[http://shop.elektroautomatik.de/shop/shop__POWER%20SUPPLY%200...84V0...3A100W__1::4::14::42::a39200116__en_GB;jsessionid=C2A626184771916CACA5FCD99944B2CB|PS 2084-03 B]] power supply.+And now I own an [[http://www.elektroautomatik.de/en/|Elektro-Automatik]] EA-[[http://shop.elektroautomatik.de/shop/shop__POWER%20SUPPLY%200...84V0...3A100W__1::4::14::42::a39200116__en_GB;jsessionid=C2A626184771916CACA5FCD99944B2CB|PS 2084-03 B]] power supply. And this fulfilled are the requirements: 
 +  * set voltage and current: in 0.1 V and 0.01 A steps 
 +  * wide voltage range (0-50 V): 0-84 V, 0-3 A (not a lot, but enough for electronics), limited to 100 W 
 +  * silent: no fan, full passive cooling 
 +  * have an earth connection: on the front panel 
 +  * not expensive: ~ 80 € 
 +  * not noname: Elektro-Automatik (never heard of it, but it's German and they have a decent website) 
 +  * provide a communication interface: USB with proprietary documented protocol
  
 +{{:ea-ps_2084-03b:dsc02164-mini.jpg?400|}}
  
 +Here some more documents about this power supply:
 +  * [[http://shop.elektroautomatik.de/shop/dos2/Web/Datenblaetter/datasheet_ps2000b.pdf|datasheet]] ({{:ea-ps_2084-03b:datasheet_ps2000b.pdf|archive}})
 +  * [[http://shop.elektroautomatik.de/shop/dos2/Web/manuale/39200112.pdf|manual]] ({{:ea-ps_2084-03b:ps_2000_b.pdf|archive}})
 +  * [[http://www.elektroautomatik.de/files/eautomatik/treiber/ps2000b/programming_ps2000b.zip|programming manual]] ({{:ea-ps_2084-03b:programming_ps2000b.zip|archive}})
 +  * [[http://www.elektroautomatik.de/files/eautomatik/treiber/usb/usb_cdc_acm_driver.zip|driver]] (USB ACM for Windows)
 +  * [[http://www.elektroautomatik.de/en/easyps2000.html|easyPS2000 software]] (Windows, demo version)
 +
 +====== measurement ======
 +
 +When powering the device on, I noticed that the voltage on the display did not change while I was turning on the knob.
 +But the Digital Multi-Meter (DMM) actually shows that the voltage actually does change.
 +Just the reading on the screen is inaccurate.
 +
 +It was time to measure how inaccurate this power supply is.
 +But doing that manually just takes to long.
 +So I decided to implement the protocol to control the the power supply, and I will measure the set output using a DMM connected to the computer.
 +
 +{{:ea-ps_2084-03b:dsc02146-mini.jpg?400|}}
 +
 +===== power supply =====
 +
 +To control the power supply I implemented the protocol described in the {{:ea-ps_2084-03b:ps2000b_programming.pdf|programming manual}}.
 +The source code is available on [[https://git.cuvoodoo.info/kingkevin/ea-ps_2084-03b/|git]].
 +
 +The [[https://git.cuvoodoo.info/kingkevin/ea-ps_2084-03b/src/branch/master/control.rb|control]] programming will increment the voltage from 0 to 84 V in 0.1 V steps, at 1.0 A.
 +It will set the voltage and current which are set, actual (measured by the power supply), and [[#mutlimeter|measured]] (measured by the DMM)
 +
 +Using [[https://git.cuvoodoo.info/kingkevin/ea-ps_2084-03b/src/branch/master/probe.rb|this script]] I could also find the following undocumented objects (for commands): 80, 81, 82, 83, 84, 85, 86, 87, 88, 149, 150, 151, 152, 156, 158, 160, 161, 162.
 +These probably allow you to flash the firmware or calibrate the power supply.
 +===== multimeter =====
 +
 +To measure the output of the power supply I used two [[http://uni-trend.com/UT61E.html|UNI-T UT61E]].
 +These are good multimeters for electronics which you can get [[http://www.aliexpress.com/wholesale?catId=0&SearchText=uni-t+ut61e|quite cheap]], with 22000 counts, and a connection to the PC.
 +More functions and its accuracy are available in the [[http://uni-trend.com/manual2/UT61English.pdf|manual]] ({{:ea-ps_2084-03b:ut61english.pdf|archive}}).
 +
 +==== connection ====
 +
 +=== UT-D02 ===
 +
 +The DMM comes with an RS232 [[http://www.uni-trend.com/en/product/2014_0626_553.html|UT-D02]] cable.
 +To connect to the PC you need a RS232 to USB converter (are PCs with COM ports still manufactured?).
 +
 +The cheapest RS232 to USB converter one is based on the CH341 chip.
 +Sadly the 7O1 mode used by the multimeter [[http://www.cnx-software.com/2015/03/07/sigrok-and-pulseview-in-ubuntu-14-04-with-uni-t-ut61e-digital-multimeter/|isn't supported]] by the linux driver.
 +I also tried the [[https://github.com/karlp/linux/tree/ch341-3.18.6|patch]], and after toggling DTR I get wrong data out.
 +
 +I also has an old ARL3116 based RS232 to USB converter, but there too the mode didn't seem to be supported.
 +
 +Finally I found a FT232-based RS232 to USB converter.
 +This is an expensive cable (but good quality), from an evil company, and it worked.
 +
 +Here is the schematic of this cable:
 +
 +{{:ea-ps_2084-03b:ut-d02.svg?400|}}
 +
 +But instead of using it, I decided to connect the cable to a CP2102-based UART to USB converter.
 +Then you have to keep two things in mind:
 +  * RS232 signals are between -12 to +12 V, while UART uses 0-5 V. This was solved by simply using the 5 V pin from the converter to power the cable.
 +  * RS232 signals are inverted compared to UART. This was solved by inverting the signal using an NPN transistor and two resistors.
 +
 +^ UT-D02 wire ^ CP2102 UART signal ^ PNP ^
 +| green | GND | |
 +| yellow | GND | |
 +| orange | 5V | |
 +| | GND | E |
 +| | 5V + 10kΩ | C |
 +| brown + 10kΩ | | B |
 +| | RX | C |
 +
 +{{:ea-ps_2084-03b:dsc02143-mini.jpg?400|}}
 +
 +=== UT-D04 ===
 +
 +For the second multimeter I used a [[http://www.uni-trend.com/en/product/2014_0626_555.html|UT-D04]] USB cable.
 +This time the data doesn't come over a serial port, but rather a HID device.
 +
 +==== communication ====
 +
 +To read the data from both multimeter I used [[http://sigrok.org/|sirgork]].
 +It supports the [[http://sigrok.org/wiki/UNI-T_UT61E|UNI-T UT61E]] and [[http://sigrok.org/wiki/Device_cables#UNI-T_UT-D02|both]] [[http://sigrok.org/wiki/Device_cables#UNI-T_UT-D04|cables]].
 +
 +Once [[http://sigrok.org/wiki/Sigrok-cli|sigrok-cli]] installed you can record the data using the following command:
 +<code>
 +sigrok-cli --driver uni-t-ut61e-ser:conn=/dev/ttyUSB0 --samples 1 -O analog
 +</code>
 +or
 +<code>
 +sigrok-cli --driver uni-t-ut61e:conn=1a86.e008 --samples 1 -O analog
 +</code>
 +depending on the cable.
 +
 +====== experiments and results ======
 +
 +I've run 5 experiments:
 +  * go from 0 V to 84 V in 0.1 V increments, without any load
 +  * go from 0 V to 84 V at 1.0 A in 0.1 V increments, with a 678 Ω load
 +  * go from 0 V to 11 V at 1.0 A in 0.1 V increments, with a 10.2 Ω load
 +  * go from 0 A to 3 A in 0.1 A increments, with a short
 +  * go from 0 A to 1 A at 10 V in 0.01 A increments, with a 10.2 Ω load
 +
 +After changing a value I've waited 3 seconds for the measurements to stabilized.
 +
 +The measurements and accuracy calculations are available in this {{:ea-ps_2084-03b:accuracy.tar.gz|spreadsheet}}.
 +
 +Here are the resulting graphs:
 +  * go from 0 V to 84 V in 0.1 V increments, without any load
 +{{:ea-ps_2084-03b:voltage-no_load-difference.svg?900}}
 +{{:ea-ps_2084-03b:voltage-no_load-set_accuracy.svg?900}}
 +{{:ea-ps_2084-03b:voltage-no_load-nominal_accuracy.svg?900}}
 +  * go from 0 V to 84 V at 1.0 A in 0.1 V increments, with a 678 Ω load
 +{{:ea-ps_2084-03b:voltage-678_ohms-difference.svg?900}}
 +{{:ea-ps_2084-03b:voltage-678_ohms-set_accuracy.svg?900}}
 +{{:ea-ps_2084-03b:voltage-678_ohms-nominal_accuracy.svg?900}}
 +  * go from 0 V to 11 V at 1.0 A in 0.1 V increments, with a 10.2 Ω load
 +{{:ea-ps_2084-03b:voltage-10_ohms-difference.svg?900}}
 +{{:ea-ps_2084-03b:voltage-10_ohms-set_accuracy.svg?900}}
 +{{:ea-ps_2084-03b:voltage-10_ohms-nominal_accuracy.svg?900}}
 +  * go from 0 A to 3 A in 0.1 A increments, with a short
 +{{:ea-ps_2084-03b:current-short-difference.svg?900}}
 +{{:ea-ps_2084-03b:current-short-set_accuracy.svg?900}}
 +{{:ea-ps_2084-03b:current-short-nominal_accuracy.svg?900}}
 +  * go from 0 A to 1 A at 10 V in 0.01 A increments, with a 10.2 Ω load
 +{{:ea-ps_2084-03b:current-10_ohms-difference.svg?900}}
 +{{:ea-ps_2084-03b:current-10_ohms-set_accuracy.svg?900}}
 +{{:ea-ps_2084-03b:current-10_ohms-nominal_accuracy.svg?900}}
 +
 +As you can see the measured values are most of the time higher than the set values, but within the 0.2 % accuracy (to 84V or 3A).
 +But the actual values displayed by the power supply is way below what is set, and outside of the accuracy, particularly on the low voltages.
 +
 +Conclusion: don't trust the displayed voltage (it's too low), but you can be confident the output is right (except for the very low voltages and currents).
 +
 +====== teardown ======
 +
 +Well laid out, good components, german quality ;)
 +
 +{{:ea-ps_2084-03b:dsc02155-mini.jpg?175|}}
 +{{:ea-ps_2084-03b:dsc02154-mini.jpg?300|}}
 +{{:ea-ps_2084-03b:dsc02151-mini.jpg?175|}}
 +
 +{{:ea-ps_2084-03b:dsc02157-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02159-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02148-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02150-mini.jpg?120|}}
 +
 +{{:ea-ps_2084-03b:dsc02156-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02160-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02163-mini.jpg?200|}}
 +{{:ea-ps_2084-03b:dsc02162-mini.jpg?200|}}
 +
 +====== conclusion ======
 +
 +pro:
 +  * fulfils all initial power supply criteria 
 +  * **set output is within accuracy**
 +  * good design, lay out, quality components
 +  * fast first contact response
 +
 +contra:
 +  * output is not switched of completely
 +  * **measured value is up to 0.4 V lower than output voltage**
 +  * second digit after . of voltage is always 0 and not settable (it should not be displayed in this case)
 +  * second digit after . of voltage is always 0 and does not show measured value (the actual measured data is precise enough to show this digit)
 +  * can skip fast knob turns
 +  * USB cable does no fit in port because of the indent
 +  * information in english programming manual missing
 +  * small mistakes in programming manual
 +  * can not be calibrated by end user, and vendor only calibrates if under warranty
 +  * no contact support
ea-ps_2084-03b.1432662063.txt.gz · Last modified: 2024/01/07 17:49 (external edit)

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