View Full Version : BS2 and transistor help.

Joe M
05-09-2006, 08:42 PM
Hello Everybody - I want to drive 4 LEDs with a transitor controlled by the bs2... So I hook up a 2n3906 to the bs2, with the power coming from VDD on the BOE. Everything here works fine, although 2 leds is all I can power with VDD.

Everything there works fine, but if I use say 8v going in to the positive on the transistor instead of vdd it doesn't work right. Is my problem simply that the 2n3906 won't switch 8volts?


Mike Green
05-09-2006, 08:55 PM
You're going to have to be more specific about what is connected to what. The 2n3906, when properly connected, can switch much more than 8v. It all depends on the details.

Tom Walker
05-09-2006, 09:16 PM
Definitely need more info.
If I had to hazard a guess, making completely unjustified assumptions about how you have it wired up, it sounds like a common ground issue.

Or, it could be that the platypus is not facing the right way....

Or the horizontal jackstaff limiter relay is sticking....

Truly Understand the Fundamentals and the Path will be so much easier...

Joe M
05-09-2006, 09:36 PM
I'm going with the platypus. That thing is always in backwards....

So after I posted it I took a look back at my breadboard and its a ground issue. Thank you guys for the info.


Beau Schwabe
05-09-2006, 11:24 PM

You will need to use an NPN (2n3904) transistor to do what you want with an 8V supply.

To see why this is, check out the link below...


Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.