electronic adjustable resistor

luka · 1st August 2006, 03:06 PM

Does any one have this kind of resistor?
For testing supplys,amps,...

mrshow4u · 1st August 2006, 03:12 PM

I'm not sure what you need. These might not deal with reverse polarities, ....I didn't check'm out. <http://www.home.agilent.com/cgi-bin/...OUNTRY_CODE=US>

luka · 1st August 2006, 03:21 PM

Yes like that, but I would like to build one myself,but I dont know where to start, and I don't have any schema for now.

mrshow4u · 1st August 2006, 03:24 PM

You could parallel up a bunch of MOSFET's and bias the gates up to make an adjustable power resistor. I've never tried that, but in concept it works. It sounds interesting

luka · 1st August 2006, 03:29 PM

That's what I thougt, but gate drive must be somewhat complicated, because it has to keep the resistance the same, independeble of voltage applyed to mosfer's.

mrshow4u · 1st August 2006, 03:34 PM

..

Yes, that's where the "fun" would come in. You'd have to monitor the summed currents, measure the voltage across the MOSFETS, then adjust the Vgs to mantain the load resistance.

luka · 1st August 2006, 03:36 PM

Now how to do that...

luka · 1st August 2006, 03:46 PM

It would be great to have adj. max current to.

luka · 1st August 2006, 04:10 PM

Uuu and max power limit.

http://www.elektor-electronics.co.uk...d=28&art=50616

jackinnj · 1st August 2006, 04:42 PM

We have a great company in NJ -- Transistor Devices -- which makes electronic loads -- they have units which will dissipate 120kW !!! Very often you will see their units for sale on EBay or at Hamfests:

1st August 2006, 03:06 PM	#1
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	electronic adjustable resistor Does any one have this kind of resistor? For testing supplys,amps,...

1st August 2006, 03:12 PM	#2
mrshow4u diyAudio Member Join Date: Jul 2006	I'm not sure what you need. These might not deal with reverse polarities, ....I didn't check'm out. <http://www.home.agilent.com/cgi-bin/...OUNTRY_CODE=US> __________________ ".........These go to eleven"

1st August 2006, 03:24 PM	#4
mrshow4u diyAudio Member Join Date: Jul 2006	You could parallel up a bunch of MOSFET's and bias the gates up to make an adjustable power resistor. I've never tried that, but in concept it works. It sounds interesting __________________ ".........These go to eleven"

1st August 2006, 03:34 PM	#6
mrshow4u diyAudio Member Join Date: Jul 2006	.. Yes, that's where the "fun" would come in. You'd have to monitor the summed currents, measure the voltage across the MOSFETS, then adjust the Vgs to mantain the load resistance. __________________ ".........These go to eleven"

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1st August 2006, 03:21 PM	#3
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	Yes like that, but I would like to build one myself,but I dont know where to start, and I don't have any schema for now.

1st August 2006, 03:29 PM	#5
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	That's what I thougt, but gate drive must be somewhat complicated, because it has to keep the resistance the same, independeble of voltage applyed to mosfer's.

1st August 2006, 03:36 PM	#7
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	Now how to do that...

1st August 2006, 03:46 PM	#8
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	It would be great to have adj. max current to.

1st August 2006, 04:10 PM	#9
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	Uuu and max power limit. http://www.elektor-electronics.co.uk...d=28&art=50616

1st August 2006, 04:42 PM	#10
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	We have a great company in NJ -- Transistor Devices -- which makes electronic loads -- they have units which will dissipate 120kW !!! Very often you will see their units for sale on EBay or at Hamfests:

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