From: jl@glen--canyon.com
On Sun, 18 Jan 2026 15:29:11 +1100, Bill Sloman
wrote:
>On 18/01/2026 10:33 am, john larkin wrote:
>> On Sat, 17 Jan 2026 15:58:01 +1100, Bill Sloman
>> wrote:
>>
>>> On 17/01/2026 4:19 am, john larkin wrote:
>>>> On Sat, 17 Jan 2026 03:59:00 +1100, Bill Sloman
>>>> wrote:
>>>>
>>>>> On 16/01/2026 11:01 am, john larkin wrote:
>>>>>> On Thu, 15 Jan 2026 23:01:38 +0000, John R Walliker
>>>>>> wrote:
>>>>>>
>>>>>>> On 15/01/2026 18:15, john larkin wrote:
>>>>>>>> On Thu, 15 Jan 2026 17:51:59 +0000, liz@poppyrecords.invalid.invalid
>>>>>>>> (Liz Tuddenham) wrote:
>>>>>>>>
>>>>>>>>> john larkin wrote:
>>>>>>>>>
>>>>>>>>>> On Thu, 15 Jan 2026 15:18:31 +0000, liz@poppyrecords.invalid.invalid
>>>>>>>>>> (Liz Tuddenham) wrote:
>>>>>>>>>>
>>>>>>>>>>> john larkin wrote:
>
>
>
>> I'll reveal the secret mathematics:
>
>The secret you reveal isn't in the mathematics. It's the thermal
>resistance from the dissipating element to ambient
No; average power is low.
What matters is microsecond-range heat capacity in the resistive
element. The ceramic substrate may help a little.
>>
>> 180 watts at 0.1% duty cycle is 0.180 watts.
>>
>> 15c divided by 0.18 is 83 watts per degree C.
>>
>> Please keep this confidential.
>
>Why? It's on the data sheet of whatever resistor you happen to be using,
>which you haven't specified. You may not realise this.
The data sheet of a cheap thickfilm resistor does not characterize it
for pulsing at 1000x rated power.
Or 2000x, which I'm running now.
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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