X-Mozilla-Keys:                                                                                 
Chuck Dunlap wrote:

Paul wrote:Great work Chuck. Do you remember the brand name?

I dont remember the brand but they all come from Taiwan with who knows what
brand on them. The one I used was a dual fan. Only one side had the tach wire. If it
has a tach, it will have three wires, the tach wire being yellow. The other side had
the tach circuit inside (a hall effect sensor) but no yellow wire. They are rather

delicate to take apart to modify but it can be done.

I will pop over to Fry's and buy half a dozen.

I could make a little switch box to use one counter and look
at each tach in turn like some EGT/CHT gauges work.

Wonderful news Chuck. Thanks.

Paul Lamar

I just got back from Fry's and I found one for $21.95 with the three
wires one of which was yellow. The dimensions of the fan are 3 inch
square and it comes with of all things a remote thermistor. Now you can
use the 
thermistor to check the temp distribution on your rad and  the inlet
and outlet water temps. Just glue the thermistors on with RTV or 5 min
epoxy. 

Thermistors are non-linear sensors so one can stick it in the kitchen 
oven with a turkey thermometer and slowly raise the oven temp while 
recording the resistance of the thermistor as a function of temp.

The name on the box was DC Brushless Fan Thermo Control Compuman.
Also there was a part number PLU #:2482160 PA-FAN8BTH.
I have not taken it apart yet but there is a snap ring holding the fan 
shaft in.

While I was at Fry's I picked up a BK Tool Kit 2704B do everything 
digital VOM and Hertz counter, transistor tester, capacitor tester
and you name it for $59.95. Nine volt battery powered of course.
All this allows real world measurements under actual conditions
while flying. Now there is no excuse for cooling problems with this 
kind of test equipment being so cheap. 

What you need now is a selector switch capable of selecting one of
six dual wire circuits. This should be available from Digi Key.
You then have six thermistors and six air flow sensors one can read.

http://www.digikey.com/

BTW in case you were wondering VOM's are analog to digital converters.

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

Great work Chuck! We all owe you a lot. Thanks

BTW I think I like your motor mount. Could you send a picture?

Paul Lamar
 
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