Re: Active Low COR
> What is the advantage of an active low COR.
Goes well with red wine...
> Most I have talked to say they have their controllers set
> that way, so I set mine that way,plus the Maxtrac I am using
> as a receiver default is active low.
Normally...
If the source device fails, the trailing device does not
receive an active low (turn-on or key on the air) logic
signal.
> I simulated a power failure to the receiver and the line
> went low and the transmitter thought it was time to
> transmit.
Normally one would hopefully expect the active low output of
a device (receiver) not to have adjacent paralleled parts
(resistors) pulling the output control (cor) line down when
the unit loses power. The "pull-up resistor" located at the
input of the trailing device ensures the receiver status on/off
doesn't matter to the controlling logic line.
So it's probably the location of a pull up resistor and now
you've described a valid reason for preferring an active high
cor in your specific situation.
> I also accidentally pulled the cord from the controller off
> the back of the receiver and again a low status and the
> transmitter thought it was time to transmit. I'm not seeing
> a benefit of a active low COR in those respects.
If you separate the transmitter from the control circuit and
install a pull up resistor (in/at the transmitter), then remove
what ever device (probably a resistor) draining the logic line
when the receiver is off... active low would be the way to go.
> Should I go to active high or since those things don't
> usually happen often leave it LOW..
> Any advice or ideas appreciated..
> 73s
If it's easy to relocate what ever pull-up resistor or function
/part from the receiver/source to the transmitter/trailing device
then smart money is on the active low operation.
In the practical world, it's probably more dependent on how easy
it is to access the circuit/pc-board to place an remove resistors.
If something original works better one way or another, then the
obvious answer is to use the converse.
When I build repeater control circuits, the source device (receiver)
is an active ground transistor/FET/relay (typical). The trailing
slave device provides the pull up resistor at its logic
input location. Each device control logic in a path is designed
this way...
If the receiver or repeater controller source device fails,
the transmitter doesn't get toggled onto the air.
And since some of your are not fond of fixed hardware transmitter
time-out timers, we get to see your stuck carriers on the air when
a hardware/software fault occurs.
cheers,
s.
