"David Lord" <sn...@lordynet.org> wrote in message
news:7upjodf9s...@mid.individual.net...
[]
I checked pps from MSF rx with digital meter and that showed a
signal but not very well. That has a 50ms pulse so 100ms from
Garmin should be as easy to spot. Analogue meters I have around
would give a much better indication.
Another alternative is a transistor + three resistors and
LED. A pot could be used for R2 to confirm voltage swing
of PPS output.
+5V -- R3 --- LED ---+
|
c
pps --- R1 ---+--- b
| e
R2 |
| |
0V ----------+------+
David
On the GPS-18 devices here, I found that an LED and 1K5 resistor alone
were adequate to indicate the PPS signal, and it pulled down the voltage
hardly at all. You could even hand hold the resistor and LED across the
relevant RS232 pins (PPS/DCD and ground). I used a low-current LED for a
brighter display.
Yours is the better way, as it loads the GPS a little less, and I know we
have had discussions about exact signal levels before.
Cheers,
David
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