On Sat, May 01, 2004 at 02:52:35PM -0400, James wrote:
> Thanks for all the useful information!
>
> To turn "on" the PNP transistor, the base has to be at least 0.6V less
> than the emitter (and also a small current needs to flow) right?

Right.

>
> So if my active low signal goes between 0 and 5V...and my motor power,
> which is connected to the emitter is 5V, then I'm set.

Presuming that you've taken care of the power and back EMF issues.

> What if my motor power was let's say 9V?  Does that mean, even though
> the microcontroller is holding the pin at 5V, the transistor would
> still turn on, because the emitter is at 9V and the base is at 5V?

That's right. Most times folks use a Darlington (or the complimentary pair
whose name starts with a SZ, szuliki?) config where the PIC drives the 1st
transistor base, which then drives the second base. Allows for higher voltage
and stiffer current for the main driver.

BAJ

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads