[arm-allstar] Fan control via GPIO and control circuit you can get from Amazon

[Doug Crompton]

Arthur,

 I assume you want to trigger it on PTT. This could be simple or more
sophisticated. For me it is simple.

The simple way is just to have a fan always running on the TX heat sink.
This is the way I do it. I run a small 12V muffin fan with a resistor in
series to lower the speed. You don't need to blow much air over a heat sink
to cool it.

More sophisticated would be to key the fan on and off with PTT or a GPIO
bit that follows PTT.  Just following PTT would not need a script. The PTT
line goes to ground in most cases on key.

Even more sophisticated would be a script that turns the fan on at PTT and
leaves it on for a period after PTT.

To me option 2 and 3 are unnecessary but if you want to do it and write a
script here is a start -

If you create events in rpt.conf like this. It will create a zero length
file every time you PTT and delete the file when you unkey. This is to a
tmp filesystem so no worry about writes.  Then you write an independent
script that looks for the existence of this file and turns the fan on and
off. This would be done by setting a GPIO or USB FOB bit. Delay could be
added in the script.

[events]
touch /tmp/RPT_TXXKEYED = s|t|RPT_TXKEYED
rm -f /tmp/RPT_TXKEYED = s|f|RPT_TXKEYED

Yet another option totally independent of the PI would be to get a temp
sensor and attach it to the heat sink that turns the fan on and off. Then
in very cold environments it would not go on unnecessarily.


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*



On Sat, Oct 27, 2018 at 11:02 AM "Arthur Putnam via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> I would like to use the following control circuit, to control a bun fan to
> cool radio.
> SunFounder Relay Module for Arduino and Raspberry Pi 5V DC Trigger by
> HIGHLO (HIGH Trigger)
>
> I am looking for script to use this control circuit and how to apply it to
> the Rpi 3+ I am using.
> Any ideas or feedback would be much appreciated.
>
>
>
>
> Arthur Putnamemail:n7mnk at yahoo.com
>
>
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