[time-nuts] Oncore 1pps driver & LED

Randy Warner Randy at synergy-gps.com
Thu May 4 15:42:08 EDT 2006


You can drive the LED from the DCD line, but along with a series
resistor you need to be sure to include an extra steering diode in
series with the LED. LED's have absolutely no sense of humor about being
reverse biased above a volt or two. This might also affect your 1PPS
pulse accuracy. If you do it this way use a high efficiency LED and draw
as little current through the LED as necessary.



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Glenn
Sent: Thursday, May 04, 2006 12:35 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Oncore 1pps driver & LED

Could I just drive the LED off the DCD line?


Randy Warner wrote:

>You "should" be alright. You're driving a lot of CAT5, but since the 
>data is only at 9600 baud you should be OK. The 1PPS on the DCD line 
>will be fine too. To blink an LED you just need to buffer the 1PPS 
>signal coming out of the UT+ as it does not have enough drive capacity.
>Just about anything will work: IC buffer or inverter (I use standard 
>74LVC04's in my designs) or just a simple xstr inverter or emitter 

time-nuts mailing list
time-nuts at febo.com

More information about the time-nuts mailing list