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IPAC and flashing LEDs

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The 80s Man:


--- Quote from: ahofle on March 22, 2006, 03:06:47 pm --- Well the lights do work and flash, but they are the inverse of what they should be.
Thx,
Andy

--- End quote ---

The same thing happend to me the first time I made a driver board. My problem was that I use NPN transistors in stead of PNP ones. Dumb me..

ahofle:

LOL OK that's my problem too then (this board has NPN transistors). 
Thanks for that clarification!  Off to radio sack I go.

whammoed:


--- Quote from: The 80s Man on March 22, 2006, 08:30:52 pm ---
--- Quote from: ahofle on March 22, 2006, 03:06:47 pm --- Well the lights do work and flash, but they are the inverse of what they should be.
Thx,
Andy

--- End quote ---

The same thing happend to me the first time I made a driver board. My problem was that I use NPN transistors in stead of PNP ones. Dumb me..

--- End quote ---

Yep, thats probably it.  The first sites I read simply said that PNP and NPN transistors "did the same thing".  Didn't actually matter for me since I am using advmame and have greater control over whether the leds are off or on.  Switch out the transistors and all should be well I would think.

whammoed:


--- Quote from: The 80s Man on March 22, 2006, 08:30:52 pm ---
--- Quote from: ahofle on March 22, 2006, 03:06:47 pm --- Well the lights do work and flash, but they are the inverse of what they should be.
Thx,
Andy

--- End quote ---

The same thing happend to me the first time I made a driver board. My problem was that I use NPN transistors in stead of PNP ones. Dumb me..

--- End quote ---

Also, I don't think it was too dumb to think you could substitute one for the other.  A few popular hits from googling don't quite reveal the difference between the two.  Here is a site that does:
http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html
There's at least two of us who thought it would be just fine.  ;)
Yes, I am still dumb, but I'm just not sure this is a defining moment...  :D

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