Re: thermal resistance, dummy loads

From	"Edward Rawde" <invalid@invalid.invalid>
Newsgroups	sci.electronics.design
Subject	Re: thermal resistance, dummy loads
Date	2026-04-23 20:44 -0400
Organization	BWH Usenet Archive (https://usenet.blueworldhosting.com)
Message-ID	<10seecr$2bbq$1@nnrp.usenet.blueworldhosting.com> (permalink)
References	<874il1tl9u.fsf@librehacker.com>

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"Christopher Howard" <christopher@librehacker.com> wrote in message news:874il1tl9u.fsf@librehacker.com...
> Hi, I'm wondering what could be used as a dummy load for testing low
> voltage, high wattage DC power supplies. E.g., I have a 12V 500W DC PS I
> wanted to test under heavy load. I see 50 ohm dummy loads for ham stuff
> are easy to get, but that would be too high a resistance for something
> like 12V.

Consider filament lamps if you can still buy them, and if you can put enough of them in
parrallel to get the load resistance you want at 12V, and if the non-linear v/i
characteristic is not an issue.

>
> I see 1 ohm, 200W resistors are easy to find, like the HS200 1R J. But
> in the fine print you've got to provide a correctly rated heatsink. When
> I did the calculations for maximum total thermal resistance, assuming
> 200W power dissipation, and some non-conservative values of standard
> room temp and a max junction temp of 200 ?, I'm looking at less than 1 ?
> / W total thermal resistance, and the heatsink ends up being five times
> the cost of the resistor.
>
> So I'm wondering what is the practical way forward. Like, put the
> resistor in mineral oil? Or get some nichrome...?
>
> -- 
> Christopher Howard

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Thread

thermal resistance, dummy loads Christopher Howard <christopher@librehacker.com> - 2026-04-23 13:33 -0800
  Re: thermal resistance, dummy loads joegwinn@comcast.net - 2026-04-23 18:32 -0400
    Re: thermal resistance, dummy loads Christopher Howard <christopher@librehacker.com> - 2026-04-23 15:15 -0800
      Re: thermal resistance, dummy loads joegwinn@comcast.net - 2026-04-24 18:12 -0400
  Re: thermal resistance, dummy loads john larkin <jl@glen--canyon.com> - 2026-04-23 17:18 -0700
  Re: thermal resistance, dummy loads Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-04-24 00:42 +0000
  Re: thermal resistance, dummy loads "Edward Rawde" <invalid@invalid.invalid> - 2026-04-23 20:44 -0400
    Re: thermal resistance, dummy loads Jeff Layman <Jeff@invalid.invalid> - 2026-04-24 08:46 +0100
  Re: thermal resistance, dummy loads Jan Panteltje <alien@comet.invalid> - 2026-04-24 07:32 +0000
  Re: thermal resistance, dummy loads liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-04-24 09:28 +0100
  Re: thermal resistance, dummy loads legg <legg@nospam.magma.ca> - 2026-04-24 11:18 -0400
  Re: thermal resistance, dummy loads Simon Simple <nothanks@nottoday.co.uk> - 2026-04-27 23:34 +0100
    Re: thermal resistance, dummy loads Jan Panteltje <alien@comet.invalid> - 2026-04-28 06:44 +0000

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