ET5410 Electronic Load mod: add external sense

[cybermaus]

Thaks.
So it is slightly newer then mine. But at it still does not work on battery test, I guess it is not so important.

Tbh, I never run into the problem. The device works well enough for me.  A more common slight annoyance I have is that the font is rather small, but that is also related to my aging eyes.

[idolclub]

I tried CR in Battery mode and agree that it does not work. when setting to low current and low voltage mode, it does not even show current flow even though it draws current.
On the attached picture you can check H/W and S/W revision # (Attachment Link)

You may try to ask "East Tester" to get a new ET5410 firmware that is newer than v1.02.2030 (Year 2020, week 30) to fix the CR Battery mode issue.

[ass20]

et5410 do not have fw update  function on menu ....
Do anybody have support email of eat tester  company?

[idolclub]

et5410 do not have fw update  function on menu ....
Do anybody have support email of eat tester  company?

https://www.easttester-cn.com/et54-series-programmable-electronic-load-product/

https://www.easttester-cn.com/contact/

[PaWill68]

Don't even rely on technical support. Forget about her.

[Algasman]

I found the pictures from my mod. They were still on my camera.
Trying to get the pics inline does not work (maybe its a Safari iPad issue). The first three pictures are taken before the modification and show the controller board attached to the front panel and the original wireing. One can see the power lines and the thin black & white sense lines

[Algasman]

Right above the relay is the connector for the sense signals. I ordered some decent Hirschmann Terminals. The big ones are 63A rated.

[Algasman]

Now to the mod: It’s quite easy, since the front panel is the same for the two channel version. So the positions for the sense terminals are defined. Just some drilling and filing necessary.

[Algasman]

The new sense wires soldering and mounted to terminals. All terminals mounted. The main lines are unaltered, just the old sense wires are cut.
The modification is really simple. I did not use a switch, just have to put a bracket between the terminals if I use it without external sensing

[cybermaus]

The new sense wires soldering and mounted to terminals. All terminals mounted. The main lines are unaltered, just the old sense wires are cut.
The modification is really simple. I did not use a switch, just have to put a bracket between the terminals if I use it without external sensing

Brackets may be as good as my switch. I hope the switch will not have contact corrosion in a few years.

More importantly, you did also not think to add polarity protection"

Alas no reverse polarity protection on the now separate sense wires, I am now wondering if I should have shorted the middle of the 4 100K resistors with a diode. After all, the TL072 can only stand -0.3V

I think a diode, with it's 0.6V threshold placed strategically in the middle of that 4x 100K network, would not at all affect precision, but if I accidentally cross the sense wires, it would deflect the negative voltage before it reaches the TL072.

But I did not take any action on it yet.

[Dwaine]

Has anyone seen the newer version with sense wires in the wild?  It's listed on their site, but I have not seen it sold any where yet.

Dwaine

[end0101]

The new sense wires soldering and mounted to terminals. All terminals mounted. The main lines are unaltered, just the old sense wires are cut.
The modification is really simple. I did not use a switch, just have to put a bracket between the terminals if I use it without external sensing

Brackets may be as good as my switch. I hope the switch will not have contact corrosion in a few years.

More importantly, you did also not think to add polarity protection"

Alas no reverse polarity protection on the now separate sense wires, I am now wondering if I should have shorted the middle of the 4 100K resistors with a diode. After all, the TL072 can only stand -0.3V

I think a diode, with it's 0.6V threshold placed strategically in the middle of that 4x 100K network, would not at all affect precision, but if I accidentally cross the sense wires, it would deflect the negative voltage before it reaches the TL072.

But I did not take any action on it yet.

Do you have any alt part suggestions for a 2n4148? Just got one of these (et5410) and planning to do the same type of mods but not finding 2n4148's other than a single ebay listing or any proper datasheets on it other than it suggests it's a thyristor in to52 from 42years ago

[cybermaus]

2N4148? Or did you mean 1N4148?

Well it is hard to remember exactly my plans, and I do not have the schematic.

But for the purpose as I remember it, placed as bridge from the middle of the bottom (GND) pair of 100K resistors, to the middle of the top (+V up to 150V) pair of 100K resistors, it does not need much in way of specs. The front resistors would pick up most voltage as well as reduce current down to a few volts and mA

It  just needs to prevent incorrect polarity from reaching the OpAmp. I think even speed is not to critical, as the OpAmp can probably handle a few useconds.

So pretty much any diode will do, 1N4148, 1N4001 up to 1N4007.

But do check precision before and after.

[end0101]

2N4148? Or did you mean 1N4148?

Well it is hard to remember exactly my plans, and I do not have the schematic.

But for the purpose as I remember it, placed as bridge from the middle of the bottom (GND) pair of 100K resistors, to the middle of the top (+V up to 150V) pair of 100K resistors, it does not need much in way of specs. The front resistors would pick up most voltage as well as reduce current down to a few volts and mA

It  just needs to prevent incorrect polarity from reaching the OpAmp. I think even speed is not to critical, as the OpAmp can probably handle a few useconds.

So pretty much any diode will do, 1N4148, 1N4001 up to 1N4007.

But do check precision before and after.

Gotcha, asked on 2n4148 because it's what you said way back in page 1 :p
So setting up like a voltage isolation transformer (to step voltage down into the range a ideal diode controller can work with) or a voltage transducer (like a v500-iso from Tifomy) and separate power feed to a ideal diode circuit/power mosfet setup wouldn't be necessary in this setup then, I also don't have a schematic.

[cybermaus]

Gotcha, asked on 2n4148 because it's what you said way back in page 1 :p

Oopsie. slip of the keyboard, will fix. I definitely meant a highly generic one, like 1N4148 or 1N4001

So setting up like a voltage isolation transformer (to step voltage down into the range a ideal diode controller can work with) or a voltage transducer (like a v500-iso from Tifomy) and separate power feed to a ideal diode circuit/power mosfet setup wouldn't be necessary in this setup then, I also don't have a schematic.

I have no idea what you mean by this.
Voltage transformer? I just suggest to clamp the voltage if you accidentally reverse connect the sense pair.
Don't want to blow out the OpAmp. But it may not even be needed.

You know what, I am going to open it up and recheck what I meant all those months back.

[cybermaus]

Ok, I opened it and added the diode(s) as in the picture
It will clamp reverse polarity to 0.6~1.0V depending on the input. (I tried up to -20V)
(images 1 & 2)

Also, I added 2x 1n4148, because the small leakage of the diode would affect precision a tiny bit.
And according to the 1n4148 datasheet while up to 5uA max, from the graph you see it is more between 10~100nA, dropping really fast if you stay away from the 75V max rating.
(images 3 & 4)

So by putting 2 diodes serial, we stay nicely away from that.
Not that anyone who buys this C brand would ever truly need that precision.

[end0101]

looks good, I was going over the unit that delivered couple days ago (mine was made jan 2021 and looks like they omitted ps2 port), and some of my igbt legs and copper bars have some of the worst joints/pin not being seated, or outright they skipped out on soldering entirely, may wanna check the joints at top and bottom on copper and igbt legs

edit: think a 1N3595 low leakage from On Semi (digikey has 1N3595TR on cuttape for 0.24 us cents ea or 10 for 2usd) would be the ideal diode? low forward @10ma (0.65-0.8 ), 150v peak, 1na @125v reverse leakage, not really doing high speed switching to need the 4ns unless I am forgetting something?

[cybermaus]

I think a 1N3595 low leakage from On Semi (digikey has 1N3595TR on cuttape for 0.24 us cents ea or 10 for 2usd) would be the ideal diode? low forward @10ma (0.65-0.8 ), 150v peak, 1na @125v reverse leakage, not really doing high speed switching to need the 4ns unless I am forgetting something?

With 1nA 150V it would surely seems like a better option.
And I see no other problems with its specs, other then the fact you would need to special order them.

But still I think the 1N4148 is quite good enough for this purpose, especially as you (presumably, like everyone else) already have those lying around.
So it is all your own choice.

And before you value my ideas about all of this: I am only a hobbyist, I am not even sure the OpAmp even needs protection.
The TL072G OpAmp specs do list -0.5V absolute max common voltage, but also -10mA (so reverse) input current.
I just got it in my head that now the sense lines are separate, so I could make the mistake of hooking them up wrong, and I guessed the diode does not make it worse (ignoring the tiny leakage current)

BTW: I did hook up the main current inputs wrong once for a handful of seconds, and it shorted out the CC power supply, but both survived.

[gico750]

Hi, I buy from aliex a ET5410, please could you explain to me why you need the modification and bring the thin wires on other bushings? thank you

[gico750]

I mean the sense wires which have been placed centrally with two bushings

[cybermaus]

@gico750

it is only needed if you want to ignore any voltage drop that your connection leads may give.


Consider the example case: 12V power supply that you want how far the voltage drops between 0-3 Amperes
If your test wires are thin, your test wires themselves may drop .5V Or more

So you measure 11.5V at 3A load, thinking that your power supply is loosing voltage quickly. But the power supply may be keeping up nicely, and it is your wires.
By moving the voltage measure point to the power supply, you eliminate this problem
Look into generic explanations of 4-wire voltage measurement and kelvin clamps.

Alternative and easier solution would be to ensure you always use thick wires, and not cheap china ones.
If you want to measure up to 3Amp, use wires that are rated to 30Amps. Or something like that.

[gico750]

thanks for the answer, yesterday the tool arrived and I would like to make this modification, so just detach the thin wires and put them thicker in the center of the panel with two bushings, but then how are they used?
Sorry but I'm not very experienced.

[gico750]

ok, i read the 4 terminal measurement and saw the kelvin tweezers ....
Now he wants to understand only the diodes you put to protect the opamp.
Are they just those two I see in the picture? Thank you

[cybermaus]

just detach the thin wires and put them thicker in the center of the panel with two bushings

They do not even need to be thicker. The sense wires can be thin.

ok, i read the 4 terminal measurement and saw the kelvin tweezers ....
Now he wants to understand only the diodes you put to protect the opamp.
Are they just those two I see in the picture? Thank you

Yes, only those two diodes in the picture. I am not even absolutely sure it is needed, but I feel it is safer.

[ceut]

Hello !
I have made a small mod for the (too loud) fan.
I use a lot 40°C Thermal Switch (Normally Open) for many devices which have too loud fan (I don't know the real name of this component).

So the Fan is completely shutted down when the temperature is under 40°C   

The mod is simple, only take time to find how to put the sensor...
Here are somes photos 
Also, you will see a "Fan Error" icon on the top of the screen, which disappears when the Thermal switch is on: it is a good feature 

I have checked with my lab powersupply at 20V/3A: no problem it works well 
(Siglent SPD3303)

Edit: I think I will buy a Noctua 80mm fan (or something like this) to replace it, too loud for me when it is active.

Edit2: Here is the no-name fan reference, 12V/0.35A/ 4500rpm