[Amps] using a scope to time relays

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Mon, 25 May 2009 11:10:08 -0600, "Steve Flood" <kk7uv at bresnan.net>
wrote:

>I'm attempting to set my input and output relay sequencing using a scope.  I am using a 9v battery source to provide the indication of contact closure.  How do you get the scope to show the actual sudden voltage change as contact closure occurs? My traces simply move up and down as I close the amp key line.  I get the impression this is a common way to set up the relays but what am I missing here?

REPLY:

You don't say what kind of scope you have, but assuming you have a
triggered-sweep  type, set the scope for normal triggering (not auto),
DC triggering  and about 5 mS per division sweep. 

It may be easier to get the triggering right using the external
trigger DC input.  Triggering off the vertical channel will work but
the trigger point will change with changes in trace position. With
external trigger, it won't. 

73, Bill W6WRT