RoboGames 2007 Scrolling LED Medal - SMBT3904 vs 2N3904 driver transistors

T&E Engineer

After comparing the original RobOlympic schematic to the new RoboGames2007 schematic I noticed the driver transistors are listed as SMBT3904.

Can standard 2N3904 NPN transistors be used as a replacement?

The symbology through me off somewhat as they look like FETs or something. I have some high current N channel FETS (and a few other high current driver parts - ULN2803? or UDN2982? ICs)·I can use too if the 2N3904 can't be used.

Also I would like to rebuild this with·some larger (2) 8x8 LED matrix instead of the (3) 5x7 matrixs - on a solderless breadboard.

I beleive the SX-28 is limited to 16 bits for arrays so it should be ok.

pwillard

It is just a 2N3904 in a surface mount SOT23 package. No clue why is shown as an FET. My data sheets show it as a standard NPN. Using SOT23 or TO92 should make little difference. So... My guess is that the symbology on that schematic isn't right.

T&E Engineer

Thanks pwillard.

My guess is that the FET symbol was carried over from the original RobOlympic schematic.