# 12vdc

**URL:** <https://community.sparkfun.com/t/12vdc/2956>\
**Category:** MicroMod\
**Tags:** msp\
**Created:** [October 20, 2006, 7:01pm UTC](https://community.sparkfun.com/t/12vdc/2956 "2006-10-20T19:01:25Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Solid\_Reign](https://avatars.discourse-cdn.com/v4/letter/s/e79b87/32.png) [@Solid\_Reign](https://community.sparkfun.com/u/Solid_Reign)\
**Post date:** [October 20, 2006, 7:01pm UTC](https://community.sparkfun.com/t/12vdc/2956/1 "2006-10-20T19:01:25Z")

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I got a development board, the olimex easyweb II, but don’t have the adapter, so I got an ac to dc converter, the thing is I’m not sure if it’s positive on the inside of the adapter or if it’s negative on the inside, I’m guessing it’s positive inside but I don’t want to fry it.

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**Author:** ![mare](https://avatars.discourse-cdn.com/v4/letter/m/49beb7/32.png) [@mare](https://community.sparkfun.com/u/mare)\
**Post date:** [October 20, 2006, 9:22pm UTC](https://community.sparkfun.com/t/12vdc/2956/2 "2006-10-20T21:22:34Z")

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> [http://www.olimex.com/dev/pdf/ARM-USB-OCD.pdf:](http://www.olimex.com/dev/pdf/ARM-USB-OCD.pdf:)  
> The inner pin of the power supply jack is +

I think olimex has all baords same polarity.

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**Author:** ![Philba](https://avatars.discourse-cdn.com/v4/letter/p/ed655f/32.png) [@Philba](https://community.sparkfun.com/u/Philba)\
**Post date:** [October 20, 2006, 9:37pm UTC](https://community.sparkfun.com/t/12vdc/2956/3 "2006-10-20T21:37:00Z")

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well, trace it out. gnd should be pretty apparent on the board, then use a DMM to see which of the jack’s pins are connected to gnd. that’s all it take.