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Electronic load MOSFET replacement

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diegobarriga:
Hello All,

I'm trying to do an electronic load as the one shown in the video
http://www.eevblog.com/2010/08/01/eevblog-102-diy-constant-current-dummy-load-for-power-supply-and-battery-testing/

Can I replace the MTP3055 FET with one of the following ones that I have available?
IRFP260
IRFZ44N
IRFP150N

Kleinstein:
The shown FETs are quite a bit larger. The IRFZ44 is more like 3 times the size - not sure if it is really well suited for linear operation. It might work at low voltage (e.g. up to 20 V).
The IRFP260 should be ok - though even bigger.

I would prefer something like an IRFP240 or IRFP250, so smaller brothers of the IRFP260, but still the large TO247 case.

The IRFP150 is not that good, as it is a lower voltage device.

Benta:

--- Quote from: diegobarriga on January 03, 2017, 05:22:42 pm ---
Can I replace the MTP3055 FET with one of the following ones that I have available?
IRFP260
IRFZ44N
IRFP150N

--- End quote ---

No.
And you can't even use an MTP3055.

Somewhere in the video (as an aside), it's mentioned that a logic-level MTP3055 is used, which is something else.

What you can and should do, is use a rail-to-rail opamp instead of the LM324.

THEN you can use all of your different MOSFETs (and the standard MTP3055).

And before someone flames me: 5 V is sufficient gate voltage to let the MOSFET work in this configuration (linear).

Benta.

diegobarriga:

--- Quote from: Benta on January 03, 2017, 11:32:46 pm ---
--- Quote from: diegobarriga on January 03, 2017, 05:22:42 pm ---
Can I replace the MTP3055 FET with one of the following ones that I have available?
IRFP260
IRFZ44N
IRFP150N

--- End quote ---

No.
And you can't even use an MTP3055.

Somewhere in the video (as an aside), it's mentioned that a logic-level MTP3055 is used, which is something else.

What you can and should do, is use a rail-to-rail opamp instead of the LM324.

THEN you can use all of your different MOSFETs (and the standard MTP3055).

And before someone flames me: 5 V is sufficient gate voltage to let the MOSFET work in this configuration (linear).

Benta.

--- End quote ---

What would be your recommendation? What I'm planning is to make an electronic load that has one 12V battery as power supply

Benta:

--- Quote ---What I'm planning is to make an electronic load that has one 12V battery as power supply
--- End quote ---

If you can supply your LM324 from 12 V instead of 5 V, it's fine and will work, also with the MOSFETs you listed. This was not clear.

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