Thanks. That was what I was looking for.Because the two junctions are not symmetrical. The doping concentrations at the base-emitter and base-collector junctions are very different.
It is explained right here on AAC:
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-2/bipolar-junction-transistors/
"Before FETs"? < > Dang, I thought I was old. </ >You can swap emitter and collector leads in a junction resistor. The swapped circuit has much less gain because the target is so small, and the collector offset voltage is very small. Before the advent of FETs, inverted transistors were often use to reduce offset.
Back during the Late Jurassic when I started as a hobbyist, I was playing with germanium transistors such as the 2N107, 2N170, CK722 and the 2N1305, as well as vacuum tubes like the 12AX7, 6AU6 and the 6L6. Good stuff."Before FETs"? < > Dang, I thought I was old. </ >
There will also be a much lower effective BVcbo, as the new "collector" won't be able to stand much more than 5-7 volts with respect to the base. This didn't used to be much of a problem with the old germanium transistors, since BVebo was often almost as high as the BVcbo.With a real world bipolar transistor you actually can swap the C and E and it will still work as a transistor, albeit with a much reduced gain of about one.
I remember them all fondly. OA2 rectifiers, Magic eye tubes used for tuning. Radios that stood on the floor. The 6L6s that powered my Ameco 40 and 80 meter transmitter kit I built. Wired chassis before there were circuit boards.Back during the Late Jurassic when I started as a hobbyist, I was playing with germanium transistors such as the 2N107, 2N170, CK722 and the 2N1305, as well as vacuum tubes like the 12AX7, 6AU6 and the 6L6. Good stuff.
I will never understand the fondness for tubes. They were hot, bulky and unreliable in rough service. The day they replaced all but one of the R390 era receivers was a day of celebration for having a few less vacuum tube era devices to maintain when I served on my first ship.I remember them all fondly. OA2 rectifiers, Magic eye tubes used for tuning. Radios that stood on the floor. The 6L6s that powered my Ameco 40 and 80 meter transmitter kit I built. Wired chassis before there were circuit boards.
(singing) Those were the days.
The OA2 wasn't a rectifier; it was a gas-discharge voltage regulator tube used more or less the way we use Zener diodes today.I remember them all fondly. OA2 rectifiers...
R390? Ah, yes. 6HA5's, 6C4's, 6BA6's. Remember them. I wasn't Radioman. I was Data System technician back before computers had ICs. When Univac was king. The Navy had some good schools back then. I spent half my enlistment in schools.I will never understand the fondness for tubes. They were hot, bulky and unreliable in rough service. The day they replaced all but one of the R390 era receivers was a day of celebration for having a few less vacuum tube era devices to maintain when I served on my first ship.
That sounds right. Thank you for correcting my failing memory.The OA2 wasn't a rectifier; it was a gas-discharge voltage regulator tube used more or less the way we use Zener diodes today.
I was a UYK-* repairman too.R390? Ah, yes. 6HA5's, 6C4's, 6BA6's. Remember them. I wasn't Radioman. I was Data System technician back before computers had ICs. When Univac was king. The Navy had some good schools back then. I spent half my enlistment in schools.
Tubes had their place, in their time just like core memory did. We still have a few for HV regulation in machines making transistors today.Don't knock tubes. They are rugged, radiation resistant devices. I repair antique auto radios, and almost never have to replace a tube. I flew as radar tech is a super constellation in the late 50s, full of tubes, but the biggest failure item was the circuit boards not the tubes.