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Welcome to JMC's Thermal Design News. The purpose
of our newsletter is to update customers about our ongoing projects.
Read ahead to
see what's happening at JMC.
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JMC has designed a new soft start circuitry to
meet Intel's in-rush current limitation requirements for high current
fan and blower applications. We have successfully implemented the
soft start circuitry so that it limits the in-rush current when
the air-moving device starts up in high duty cycles. This feature
is available in our 60x38mm DC fan form factor and will be implemented
in other form factors by customer demand. The soft start circuit design is notably beneficial
in our PWM fan designs. In traditional PWM fans, a current spike
was experienced at start up. Due to this, the power supply would
not turn the application on because the fan required too much power.
This was particularly a problem when working with an application
that contained multiple fans such as fan trays. With JMC's soft
start PWM fans, the fan start-up current draw is low and doesn't
consist of a current spike. Therefore the application will turn
on without any obstacles caused by the fan. |
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Life Testing of JMC Fans The bearing system incorporated in DC fans is
the determining factor in the life of a fan. Electronic component
failures in the circuitry of the fan are insignificant in comparison
with bearing system rates of failure. Bearing system life is measured
by
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Testing PWM Fans In order to test a PWM fan, JMC suggests using a function generator to apply the duty cycle and frequency PWM signal. You will also need a frequency counter to count the tachometer signal returned from the fan or the actual revolutions of the fan. JMC uses an Agilent 34970A data acquisition unit with one 43901-switch module to measure the tachometer, voltage, current, and temperature. We then use an Agilent 33220A function generator to apply the PWM signal. To read our Frequently Asked Questions page on
PWM fans,
CLICK HERE. |
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Riddle Me This - Enter to Win
A man, when asked by his niece how old he
was, replied,"My age is now four times yours, but five years ago
it was five times yours." How old was he? Congratulations to our Jan/Feb winner Sharad Shah
of AMD who won a JMC polo shirt! Jan/Feb Riddle:
If this sum is correct, what digits do A and M represent: MA + A
= AM. Answer: M = 8, A = 9. . |
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an L10 testing process. In all cases the MTTF (Mean Time To Failure)
and MTBF (Mean Time Between Failure) of the electronic components
is many times greater than the L10 bearing system life measurements.
JMC uses only top graded bearings to prevent side loading and hence
provide better dynamic and static loading stability and wear. As
the bearings wear, loading begins to occur and the failure mode
begins.
Email
us your answer by replying to this message. If you are correct,
we will enter your name to win the April giveaway - a JMC polo shirt!
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