[TenTec] Noise from Fans

[Mike Bryce]

Guys,

I’ve designed a small circuit that will run the a dc fan at high speed for a dozen seconds then drop the speed down to as low as it will run.

That way, the fan is sure to start, no matter how much cat hair it’s sucked up, or the condition of the bearings. Once started, runs at full speed for a bit,  then it slows downs.

both the fast on and slow run speeds are adjustable.

input voltage may be either 6.3 v ac, 12 v ac, or 12-18 v dc.

The prototype pcbs should be here within a week or so.

The circuit is simple, four transistors, a LM317 and a few diodes.


Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o 

A man with one clock knows what time it is. A man with two clocks is never sure. 



On Mar 7, 2014, at 12:16 PM, Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de> wrote:

> A few diodes would be cheaper than lots of beer.
> You don't even have to calculate much.
> Just figure on 0.6v drop per resistor.
> I buy these diodes generally 100 at a time.
> They cost just a few pennies each in those quantities.
>