Products > Test Equipment
ET5410 Electronic Load mod: add external sense
klausES:
Yes, it is a shame that even the newer A+ models External Sense is still missing.
That's why I struggled with myself for longer whether I should take it or not
until I decided to create a way to compensate for the voltage drop until the entrance for my device.
cybermaus:
Well, I checked, no calibration in software version 1.02
Also, if you think calibration would be useable for sense-compensation, you might be mistaken.
as you probably know, the voltage drop will vary with current as well as temperature. You'd have to have a separate calibration value for each cable and each current that you might use.
You do not need a exterbal sense, if you just want to stress test some power supplies, and need to dump the energy somewhere.
A simple multi-meter could be your voltage sense.
However, if you want to test some batteries, or simply want to have the convenience of not having to hook up an extra multimeter, yeah, it is a bit silly they still sell this without sense wires.
mawyatt:
--- Quote from: andobovsayvkub on March 16, 2024, 11:35:24 pm ---Hello. I just made a connection for 4 wires on 5410A+. I cut the traces and simply added a 22 ohm resistor between +V and +SENSE. Setting more then 20 Ohm will lead to an measurement error with 2-wires, and low values will cause voltage drop with 4-wires.
This made it possible to use both a 2-wire connection and a 4-wire connection without adding a switch. The standard behavior of the device has not changed.
Yes, it is possible that a voltage error may occur with a 2-wire connection but no more than 1 in the last digit on the screen. Tested in the range of 5-60V, 0-25A. And it still measures absolutely accurately with 4-wires connection. Also thinking of diode protection, but later.
part of original
(Attachment Link)
new one
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appearance
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And one more moment. The motherboards have been replaced due to a transistor that burned out on the first day. And I can't remember if the "software sense" function worked correctly when measuring the resistance of the wires connected to the battery or to other weak source.
The line resistance measurements are correct with a laboratory power supply. But when I try to measure the line resistance with the battery connected, I get incorrect data as the source voltage has a drawdown. Is it like this for everyone or is the new board also defective?
That was my the main reason to transfer it to 4-wires schema.
--- End quote ---
Interesting and clever mod :-+
Would think you would also want a 22 ohm resistor between the - Power terminal and 119.2K 199.2K resistor and "SENSE -" between to balance out the differential amplifier.
Best,
klausES:
--- Quote from: cybermaus on June 21, 2024, 06:44:21 pm ---Well, I checked, no calibration in software version 1.02
...
--- End quote ---
Thanks for the info.
--- Quote from: cybermaus on June 21, 2024, 06:44:21 pm ---...
Also, if you think calibration would be useable for sense-compensation, you might be mistaken.
as you probably know, the voltage drop will vary with current as well as temperature. You'd have to have a separate calibration value for each cable and each current that you might use.
...
--- End quote ---
No fixed values, i was already thinking of an activable / deactivable external sense (at the moment with a front microbutton, logical flipflop und gas tube relay).
Since i couldn't find a circuit diagram from Kunkin KP184, i would be interested to know how the Kunkin reacts
if you activated ext Sense in your menu and then didn't connect the sense cable to the source ?
cybermaus:
--- Quote from: klausES on June 22, 2024, 01:38:51 am ---if you activated ext Sense in your menu and then didn't connect the sense cable to the source ?
--- End quote ---
Not sure for that model, but for my model,
I described that on the very first post of this thread:
--- Quote from: cybermaus on September 25, 2020, 06:11:01 am ---Originally, I had some worry on how the device would respond if there was accidentally no voltage on the sense wires. I worried about software hanging with "divide by zero errors", but it is behaving perfectly:
- CC mode: it does not care, just keep drawing the current, but V and W display go to 0, and back up when reconnect
- CP, CR and CV mode : the device just stops drawing current, but does not hang, Reconnect, and it starts up again.
Even repeatedly switching from internal to external sense seems to not bother the device.
--- End quote ---
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