ea-ps_2084-03b
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ea-ps_2084-03b [2015/05/26 18:36] – measurement part 1 kingkevin | ea-ps_2084-03b [2015/06/03 21:35] – experiments kingkevin | ||
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* [[http:// | * [[http:// | ||
* [[http:// | * [[http:// | ||
- | * [[http:// | + | * [[http:// |
====== measurement ====== | ====== measurement ====== | ||
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The [[https:// | The [[https:// | ||
- | It will set the voltage and current which are set, actual (measured by the power supply), and [[#mutli-meter|measured]] (measured by the DMM) | + | It will set the voltage and current which are set, actual (measured by the power supply), and [[#mutlimeter|measured]] (measured by the DMM) |
- | ===== mutli-meter | + | ===== multimeter |
+ | To measure the output of the power supply I used two [[http:// | ||
+ | These are good multimeters for electronics which you can get [[http:// | ||
+ | More functions and its accuracy are available in the [[http:// | ||
+ | ==== connection ==== | ||
+ | |||
+ | The DMM comes with an RS232 [[http:// | ||
+ | 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:// | ||
+ | I also tried the [[https:// | ||
+ | |||
+ | 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. | ||
+ | |||
+ | 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. | ||
+ | |||
+ | More details about the cable and modification is described in this picture: | ||
+ | |||
+ | For the second multimeter I used a [[http:// | ||
+ | This time the data doesn' | ||
+ | |||
+ | ==== communication ==== | ||
+ | |||
+ | To read the data from both multimeter I used [[http:// | ||
+ | It supports the [[http:// | ||
+ | |||
+ | Once [[http:// | ||
+ | < | ||
+ | sigrok-cli --driver uni-t-ut61e-ser: | ||
+ | </ | ||
+ | or | ||
+ | < | ||
+ | sigrok-cli --driver uni-t-ut61e: | ||
+ | </ | ||
+ | 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 {{: | ||
+ | |||
+ | Here are the resulting graphs: | ||
+ | * 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 | ||
+ | {{: | ||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | 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). |
ea-ps_2084-03b.txt · Last modified: 2024/01/07 17:49 by 127.0.0.1