At 01:19 PM 6/5/2004 -0700, you wrote:
>Yeah, it's working because it has been reverse biased, but it should not
>be as bright as if it were in the correct way.
>
>-Shawn

It will still likely be saturated. "Real" 2N2222/2N2222A transistors are in
metal TO-18 case, and the plastic versions have bastardized part numbers
such as PN2222.

2N2222/2N2222A
http://www.semiconductors.philips.com/acrobat/datasheets/2N2222_CNV_2.pdf


PN2222A
http://www.fairchildsemi.com/ds/PN/PN2222A.pdf
http://www.rohm.com/products/databook/tr/pdf/umt2222a.pdf
http://www.ece.utexas.edu/~valvano/EE345L/DataSheets/PN2222-D.pdf

Reverse beta of such a transistor is almost surely enough to saturate
it in the given circuit (forced beta ~5), so it will work either way.
Typically it's probably more like 10 or 15.

Note that the breakdown voltage Vceo is now limited by the Vebo
maximum, which is only 5 or 6 volts. And vice versa. That doesn't matter
in a 5V-only circuit, of course. It can be handy if you need a
transistor with a very high Vebo, and there are also some advantages
in terms of the saturation voltage.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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