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ET5410 Electronic Load mod: add external sense

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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:

--- Quote from: cybermaus on April 20, 2021, 07:08:43 pm ---
--- Quote from: Algasman on April 16, 2021, 06:55:09 pm ---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

--- End quote ---

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"

--- Quote ---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
--- End quote ---

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.

--- End quote ---

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:

--- Quote from: cybermaus on April 25, 2021, 04:26:06 pm ---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.

--- End quote ---

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:

--- Quote from: end0101 on April 26, 2021, 09:01:32 am ---Gotcha, asked on 2n4148 because it's what you said way back in page 1 :p

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


--- Quote from: end0101 on April 26, 2021, 09:01:32 am ---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.

--- End quote ---
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.

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