Re: [ATM] Electronics help needed - temperature control

["Don Clement" <clement.focuser@verizon.net>]

The 555 timer IC is very useful component. The ubiquitous 555 IC can be
found in many commercial circuits from dew controllers to PWM motor
controls. The 555 IC is readily available and easy to use. Here is an on
line tutorial:

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

-Don

>
> Mark,
>
> I think your idea of the shunt and swapping the sensors would work. I have
a
> suggestion: Use a 555 timer IC between the output of the comparator and
> switch. Use the comparator to change the duty cycle of the 555 driving the
> switch.  A 50% duty cycle could have the fans running at half speed for
> example.  Then up the duty cycle to 100% and the fans would go full blast.
> This way energy isn't being wasted with a shunt and the switch could drive
> one fan or many fans without changing circuit components.
>
>

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