[time-nuts] 1pps signal presence with no GPS signal.

David Kirkby david.kirkby at onetel.net
Sat Jul 9 06:09:50 EDT 2005

Bill Janssen wrote:
> David Kirkby wrote:

>> PS,
>> A couple of suggestions on how I think the Synergy SynPaQ III could be 
>> improved, if people choose to mount it inside another enclosure.

>> 2) Have some method of bringing the drive to the LEDs out of the box, 
>> so  they can be replaced by LEDs on a front panel. I'd like to get the 
>> 1pps LED to a front panel, but short of soldering wires onto the PCB, 
>> that is not possible. I might either use a light pipe, or use the 1pps 
>> output and put it into a pulse stretcher, so it can drive an LED on a 
>> front panel. I'm not sure of the speed of a 555 timer, but I suspect 
>> that will do the job of stretching the pulse to something that is 
>> reasonable for an LED. But it would make life a lot easier if those 4 
>> LEDs could be bought onto a front panel with not too much hassle.
>> David Kirkby
> Well you could use some sleeving to attach photo transistors on the 
> existing LED's and use
> that to drive your front panel LED's. Kinda haywire but you don't have 
> to modify a board.
> Think of it as a electronic light pipe.
> Bill K7NOM

I did modify the case by drilling/tapping a couple of holes to mount the 
box, but do not intend modifying the PCB to get some light out.

The photo transistor or photo diode plus an LED is certainly one way out.

However, having thought about it more carefully, 3 of the 4 LEDs could 
probably be driven from the 9-pin RS-232 port on the box, without the 
need for an optical detector. The 1pps appears on pin 1, the TXD on pin 
2 and the RXD on pin 3, with pin 5 common. I assume just using those 
lines to switch a transistor would work fine - it might even be possible 
to drive a low current LED directly with a resistor.

I'm not sure about the DIFF LED though. That might be possible to get 
from the connector on the front, although I am not using that at all, 
and the LED has never lit.

So I think my critisism about the LEDs was unfair, although I still 
think it could benefit from a better method of mounting it.

David Kirkby,

Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/

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