Gareth Magennis wrote in message
...


"amdx" wrote in message
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On 3/28/2012 9:07 AM, N_Cook wrote:
Under thermistor control. If at power up the DC voltage is too low to
start
the fan can you always rely on the fan starting at some point with a
slowly
increasing voltage or does it depend on the make/design of fan ?


Different fans will start at different voltages.

Your circuit is NOT a thermistor and a fan in series, right?
Mikek



I think the question is will the fan ALWAYS start with a slowly ramping
voltage, rather than perhaps sit there in a stalled state.



Gareth.


3 fans fed from the same varying supply. 2 large , one small, all nominally
12V. The 2 large start with the applied "cold" voltage and eventually the
small one starts with warming of the amp . Checked by slowly powering from
a bench ps a few tmes . But I randomly picked up another new fan that I had
about and once out of 10 or so times it did not start by the time it had
reached 12V. I decided as this amp was never used for low power use that I
would disable the ramping and set it on maximum drive always, not worth the
risk/inconvenience of stressed components/mid-performance chance of a cut
out