User Timers
20-7
Example: Fan Control
Installing a fan to cool a repeater or link transmitter is always a good idea. It
can extend the life of the transmitter significantly. But, leaving the fan running
all the time will shorten the life of the fan.
To extend the life of the fan, the fan can be operated whenever the transmitter
is keyed and for a couple of minutes after. A User Timer can be used to
control the amount of time the fan stays on after the transmitter unkeys.
Three macros will be required to implement the fan control: one is triggered
when the transmitter is keyed, a second is triggered when the transmitter is
unkeyed, and a third is triggered when the timer times out. To control the fan,
a Logic Output will be used to power the fan through a switching device, e.g. a
relay or HexFET.
For this example, we’ll create macros 8701, 8702, and 8703. We’ll use timer
#9 and logic output #1.
First, setup the timer and assign the macros.
; Setup
(PW) 49 09 03 1200 * ; Set Timer 120.0 seconds
(PW) 49 09 02 8703 * ; Set Timer Macro
(PW) 26 82 8701 * ; Set Tx1 Active Macro
(PW) 26 84 8702 * ; Set Tx1 Inactive Macro
Enter the macro that is triggered when the transmitter is keyed. This macro
stops the timer and enables the logic output to activate the fan for the entire
time that the transmitter is keyed.
; Macro: Tx1 Active: Stop Timer, Logic Out On
(PW) 20 8701 (PW) 49 09 00 * ; stop timer
(PW) 29 8701 (PW) 701*;Logic Out 1 ON
Enter the macro that is triggered when the transmitter is unkeyed. This macro
starts the timer and leaves the fan on.
; Macro: Tx1 Inactive
(PW) 20 8702 (PW) 49 09 01 * ; start timer
Enter the macro that is triggered when the timer times out. This macro turns
off the fan.
; Macro: Timer Timeout
(PW) 20 8703 (PW) 711*;Logic Out 1 OFF
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