[Amps] Controlling blower fan speed...

[Gary Schafer]

thaxton@ptgroup.com wrote:

> I'd like to hear from anyone who has constructed/ designed/jury-
> rigged, a fan speed controler for the tubes in their amp.
>
> I found a couple of squirell cage blowers that I'd like to adapt and
> control their speed for my amp.  The oem blower does about
> 30cfm.  The blowers I picked up are 50 and 60cfm blowers.  I'd like
> to be able to control their speed and reduce their output when I'm
> just loafing, i.e. 500watts or less, and then have the fans crank up
> when I kick in more power, i.e. 600 to 1500 watts.  All of this
> perhaps to be controlled by a temperature sensor above and/or
> around the tubes of my amp.
>
> Has anybody developed a methodology to do this??  Any help,
> pointers to info, real life experience, advice, would be appreciated.
>
> thanks....
>
> Don/N0FGK
>

I have used a series capacitor to slow the blower speed down. Then place
a temperature switch above the tube in the air path that will short out
the capacitor when things heat up.

73
Gary  K4FMX