Model 152 PSU dummy loads - Re: NeXT Cube - powers on briefly then off again

[Ian Finder]

Not sure how much of a noob you are, although you repeatedly claim to be
one so just on the safe side we'll cover some Engineering for Poets (or
Programmers) to reassure you ;) --

V = I * R
Power (watts) = I * V

You know the voltage of the monitor. You know the resistance of your
resistor. So, you also know the maximum power the resistor needs to be
rated to dissipate.

If the spec says the single air-cooled resistor you're buying is good to
dissipate X watts into ambient temperature Y, I'd just go ahead and believe
it.

Make sure the numbers work out and you're fine, no heavy duty HVAC needed.
:-P

Cheers,

- Ian

On Mon, Oct 26, 2015 at 10:52 AM, Toby Thain <toby at telegraphics.com.au>
wrote:

> On 2015-10-26 1:23 PM, Ian Finder wrote:
>
>> This thread took a turn for the absurd. Oil? Water? What a practical
>> bunch of people. /s
>>
>> They make resistors with adequate cooling... Almost as if they're
>> rated for a certain number of watts of dissipation and you can buy
>> them based on that. They are resistors after all.
>>
>> And if they overheat-- oh wait, they're heavy duty resistors, not
>> ICs. Get a couple, put them in a metal project box, put it inline
>> with the cable, and call it a day.
>>
>
> Damn, I already ordered a pile of HVAC gear.
>
> j/k - yeah that was what I was basically planning, Ian ... just as a noob,
> I'm not totally confident with what a single air cooled part can dissipate.
>
> (The thread was kind of interesting anyway!)
>
> --Toby
>
>
> Sent from my iPhone
>>
>> On Oct 26, 2015, at 09:24, simon <simski at dds.nl> wrote:
>>>
>>> please skip this ridicule and grab yourself a couple of headlights from
>>> a car.
>>>
>>>
>>>
>>> On 26-10-15 17:16, Dale H. Cook wrote:
>>>> My recommendation of oil is based upon my decades of experience with
>>>> broadband dummy loads from 60 watts to 2.5 kilowatts. The dummy loads that
>>>> I have worked with for medium wave and below and from 5 kilowatts down have
>>>> all been convection air cooled. Broadband dummy loads that I have used for
>>>> higher powers (up to 25 kilowatts) have been forced air cooled.
>>>>
>>>> I prefer to stick with what I have experience with. As for water, YMMV.
>>>>
>>>> Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
>>>> http://plymouthcolony.net/starcityeng/index.html
>>>>
>>>
>>> --
>>> Met vriendelijke Groet,
>>>
>>> Simon Claessen
>>> drukknop.nl
>>>
>>
>>
>


-- 
   Ian Finder
   (206) 395-MIPS
   ian.finder at gmail.com