X-Mozilla-Keys:                                                                                 

Chuck, I assumed you connected the red wire to 12 volts to power the
tach. Correct? PL

Chuck Dunlap wrote:

I did'nt use the red wire at all, just tied black wire to
ground, and used a 9 volt battery, plus side thru a 180 ohm
pull-up resistor to the yellow wire, minus side to ground. The
voltage is not critical, 12 volts would work fine, the battery
was just easier to wire for a temporary setup.

Make sure you orient the same direction of airflow for
calibration as you mount it in the duct - I measured a 50%
difference in speed front to back due to the shape of the
blades.

Chuck Dunlap


Thanks for the tips Chuck. I will wire it up and 
stick it on my scope tomorrow.

Paul Lamar
 
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