Saturday, April 21, 2012

DP-9 Connector Breakout Board


or

Why You Should Take the Time to Build Yourself the Proper Tools

I'm really kicking myself tonight; I was working on my frequency counters, and finally got them into a state working enough that I was able to fire up my Rubidium frequency reference and phase compare it to my GPS time source and see if there is a measurable difference between them.
This is my Rubidium frequency reference.  It outputs a very good 10MHz sine wave, and a TTL one pulse per second, both derived for an intrinsic physical property of elemental Rubidium, meaning this is something on the order of a million times more accurate than your typical wrist watch.  The Rb reference needs both 5V and 15V, for the TTL logic and the heater, respectively.  I want you to notice how I have 15V stupidly fly-wire clipped next to all those TTL I/O pins on the same DB-9 connector...

I came to regret that tonight.  I bumped the setup, and managed to short the 15V power pin to the /LOCK pin, putting 15V onto all of the logic, and made both my Rb reference and power supply very cranky.  This released the magic blue smoke from my Rb reference, which now has little use beyond being an impressive, but painfully expensive, heated drink coaster...
This was stupid, because I was cutting the corner of sitting down and only taking the 15 minutes it would take to build the proper breakout board.  People don't appreciate this, and I'm certainly guilty of this, but when you're working on a project, you (should) often end up spending more time building the jigs, frames, and target boards that will make the project turn out better than actually working on the final project itself.

It isn't glamorous, and it doesn't feel like you're getting anything useful done, but the 15 minutes I just spent building this would have saved me a $50 part, and now it's sitting in my "connectors" junk box, ready to go the next time I need to probe a DB-9 connector for something.
Lesson learned, and it cost me a $50 part.  Hopefully you heed my advice and take the extra time to be careful the first time.

2 comments:

  1. i think we've all done that... don't beat yourself up too much... ;>(

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  2. "...you (should) often end up spending more time building the jigs, frames, and target boards that will make the project turn out better than actually working on the final project itself."

    I'd say this is true in almost any endeavor. My family does custom cabinetry and I remember growing up my dad would always put a lot of effort into his jigs.

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