Jim Stewart wrote:
On 07/03/2020 08:46, Rod Speed wrote:
Jim Stewart wrote
I take it car blower resistor packs are cooled by the airflow of the
fan they are controlling....?

Unlikely they use resistor packs anymore.
what is used then ? .....

Electronic control using MOSFETs probably, switch the power to the
motor on and off very fast varying the on/off ratio to give speed
control. There are lots of speed control chips available off the
shelf for driving the MOSFET, overall very cheap to implement nowadays
and can easily be well over 90% efficient as MOSFETs are very nearly
perfect switches.

--
Chris Green
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