>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??
Tektronix was doing this over a decade ago. A thermistor controlled the
base current flow through a pass transistor whose emitter drove a DC
brushless fan. The hotter the thermistor got, the faster the fan ran.
Thus, the air exhaust temp was fairly constant but as things heated up in
the o'scope, noise and air volume increased proportionately.
>Any help,
>pointers to info, real life experience, advice, would be appreciated.
>
>thanks....
>
>Don/N0FGK
>
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- Rich..., 805.386.3734, www.vcnet.com/measures.
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