"Dave D" wrote in message ...
"Robert Morein" wrote in message
...

snipped

In my experience with 12V fans,

They're 5V fans.

a series resistor works nicely, as does
running them from a stiff 6V supply.

A series resistor generates heat, diodes drop voltage and run cooler.. They
can be soldered into the fan leads then covered with heatshrink sleeving. A
6V supply will speed these fans up.

I tried running the unit off 4.5 V and it works - but almost no torque .


Unless you have something unusual, these fans do vary RPM in response to
power supply voltage.

You will have to determine the resistor by trial and error, since the fans
do not respond linearly to voltage.



Silicon diodes in series allow small increments and an easier way to select
the required speed.

Interesting idea - thanks


BTW, you replied to my post, I did not post the query :-) Maybe your news
service isn't showing all the posts?

Dave