On Fri, 3 May 2002, Dwayne Reid wrote:

>At 10:48 PM 5/2/02 +0300, Peter L. Peres wrote:
>>On Wed, 1 May 2002, Eoin Ross wrote:
>>
>> >Any ideas on how to add a speed controller to my heat gun? I
>>
>>Switching a simple diode in series with it will reduce the power a little
>>(30% or so).
>
>Actually, adding a series diode reduces the power by exactly 50% (1/2).

You are correct, I had lightbulbs in mind, and the real situation where
switching a diode in series with a blower does not cut the temperature or
the heatflow in half. It cuts the power in half. And airflow and heat are
coupled so the temperature drops about 30% in this case. For the subject
at hand (carpet blower) from 420C to about 270C which is just right for
SMD work with some care. These are real measured numbers, unlike the goof
above.

thanks for pointing out the goof,

Peter

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