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--- ea-ps_2084-03b [2015/05/27 22:21] – [connection] kingkevin
+++ ea-ps_2084-03b [2015/06/07 19:03] – add picture kingkevin
@@ Line 27: / Line 27: @@
   * 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:
@@ Line 44: / Line 46: @@
 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 =====
@@ Line 60: / Line 64: @@
 ==== connection ====
+=== UT-D02 ===
 The DMM comes with an RS232 [[http://www.uni-trend.com/en/product/2014_0626_553.html|UT-D02]] cable.
@@ Line 78: / Line 84: @@
   * RS232 signals are inverted compared to UART. This was solved by inverting the signal using an NPN transistor and two resistors.
-More details about the cable and modification is described in this picture:
+^ 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.
@@ Line 97: / Line 114: @@
 </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 lay 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|}}