Maker Pro
Maker Pro

How would one use NPN transistors only?

B

B

Jan 1, 1970
0
All:

I am familiar with the typical amplifier using NPN, and PNP
transistors. It just makes good common sense, even to lay people like
me.

What about amplifiers that use ONLY NPN transistors? How would that
work? It may be elementary, but when I am trying to theorize that, it
just doesn't make sense to me.

There are a few people now building amplifiers with only NPN
transistors, and I understand the advantages, but I don't understand
how they make it work.
 
H

Hank

Jan 1, 1970
0
B said:
All:

I am familiar with the typical amplifier using NPN, and PNP
transistors. It just makes good common sense, even to lay people like
me.

What about amplifiers that use ONLY NPN transistors? How would that
work? It may be elementary, but when I am trying to theorize that, it
just doesn't make sense to me.

There are a few people now building amplifiers with only NPN
transistors, and I understand the advantages, but I don't understand
how they make it work.

What type of amplifier are you talking about? I can build a class A amplifier
all day long with just one npn transistor.
 
A

Activ8

Jan 1, 1970
0
On Tue, 08 Jun 2004 16:19:42 GMT, Hank wrote:

What type of amplifier are you talking about? I can build a class A amplifier
all day long with just one npn transistor.

It takes you all day? ;)
 
J

John Larkin

Jan 1, 1970
0
All:

I am familiar with the typical amplifier using NPN, and PNP
transistors. It just makes good common sense, even to lay people like
me.

What about amplifiers that use ONLY NPN transistors? How would that
work? It may be elementary, but when I am trying to theorize that, it
just doesn't make sense to me.

There are a few people now building amplifiers with only NPN
transistors, and I understand the advantages, but I don't understand
how they make it work.

Advantages?

John
 
M

MikeM

Jan 1, 1970
0
B said:
All:

I am familiar with the typical amplifier using NPN, and PNP
transistors. It just makes good common sense, even to lay people like
me.

What about amplifiers that use ONLY NPN transistors? How would that
work? It may be elementary, but when I am trying to theorize that, it
just doesn't make sense to me.

There are a few people now building amplifiers with only NPN
transistors, and I understand the advantages, but I don't understand
how they make it work.

How did they manage when all they had is tubes?
Tubes are like NPNs; there were no PNP tubes...

MikeM
 
W

Winfield Hill

Jan 1, 1970
0
MikeM wrote...
How did they manage when all they had is tubes?
Tubes are like NPNs; there were no PNP tubes...

In the early Ge transistor days, everything was all PNPs. :>)

In tube days the issue of making multistage dc amplifiers (that's
where one runs into a problem) was handled with fixed-voltage
level shifters, made from resistors, or from neon lights. In
more recent times with early ICs that were NPN only, resistors
were used, both as voltage dividers and with current sinks, as
well as 6V zener diodes (made from reversed-BE junctions).
Examples can be seen in the old uA702, uA709 and uA715 opamps.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)
 
T

Tim Wescott

Jan 1, 1970
0
MikeM said:
How did they manage when all they had is tubes?
Tubes are like NPNs; there were no PNP tubes...

MikeM

Yea, it's a bitch keeping the antimatter tube elements connected up to
the rest of the device - but heating the cathode really isn't a problem.
 
H

Hank

Jan 1, 1970
0
Activ8 said:
On Tue, 08 Jun 2004 16:19:42 GMT, Hank wrote:



It takes you all day? ;)

It takes about 1 minute. I spend the rest of the day wasting my time on the
internet. :)
 
A

Activ8

Jan 1, 1970
0
It takes about 1 minute. I spend the rest of the day wasting my time on the
internet. :)

At least you have your priorities straight ;)
 
A

Activ8

Jan 1, 1970
0
How did they manage when all they had is tubes?
Tubes are like NPNs; there were no PNP tubes...

MikeM

With a transformer. You can find plenty of Marshall and Fender Amp
schems out there as examples.
 
D

Del Cecchi

Jan 1, 1970
0
Activ8 said:
With a transformer. You can find plenty of Marshall and Fender Amp
schems out there as examples.

Don't need transformer. But no one said what kind of amp. If you talking
audio amp, go to the library and look at old old late 60's issues of
"popular electronics" or "radio Electronics" or evne the british "wireless
world".

I might even have one in my file. Basically the output stage is an emitter
follower for the pull up and a common emitter stage for the pull down.
Drive the bases out of phase, and away you go.

del cecchi
 
K

Ken Smith

Jan 1, 1970
0
B said:
What about amplifiers that use ONLY NPN transistors? How would that
work? It may be elementary, but when I am trying to theorize that, it
just doesn't make sense to me.

Consider this circuit:
Vcc
!
\
/R1
\
!-----------------------
! !
\ Vcc -----
/R2 ! ----- C1
\ !/ !
!----------! Q2 !
!/ !\ !
-! Q1 !------------------- To load
!\ !
! !/
!----------! Q3
\ !\
/ R3 !
\ GND
!
GND

If Q1 is on, Q3 is also on and Q2 is off so the output swings down to
ground. If Q1 os off, Q3 is alos off and R1 and R2 pull up on Q2 turning
it on and the output swings up near Vcc. If Q1 is partially on, Q3 is
also partailly on so some current flows through it. There is some voltage
drop on the R1, R2 combination so the base of Q2 is at some middle voltage
and thus the output will be somewhere in the middle.

This circuit doesn't work in real life because as the temperature changes,
the current through Q2 and Q3 goes all over the place. At least, a
resistor in the emitter of Q3 should be added before you tinker the
circuit together.

"What does C1 do?" I hear you ask. Well imagine the circut is making a
small sinewave on its output and that C1 is huge. How much AC current
flows in R2?
 
I

Ian Bell

Jan 1, 1970
0
MikeM said:
How did they manage when all they had is tubes?
Tubes are like NPNs; there were no PNP tubes...

MikeM

Same as when all they had was PNPs - they used transformers.

Ian
 
J

Jan Panteltje

Jan 1, 1970
0
On a sunny day (Tue, 8 Jun 2004 21:28:16 +0000 (UTC)) it happened
Consider this circuit:
Vcc
!
\
/R1
\
!-----------------------
! !
\ Vcc -----
/R2 ! ----- C1
\ !/ !
!----------! Q2 !
!/ !\ !
-! Q1 !------------------- To load
!\ !
! !/
!----------! Q3
\ !\
/ R3 !
\ GND
!
GND

If Q1 is on, Q3 is also on and Q2 is off so the output swings down to
ground. If Q1 os off, Q3 is alos off and R1 and R2 pull up on Q2 turning
it on and the output swings up near Vcc. If Q1 is partially on, Q3 is
also partailly on so some current flows through it. There is some voltage
drop on the R1, R2 combination so the base of Q2 is at some middle voltage
and thus the output will be somewhere in the middle.

This circuit doesn't work in real life because as the temperature changes,
the current through Q2 and Q3 goes all over the place. At least, a
resistor in the emitter of Q3 should be added before you tinker the
circuit together.

"What does C1 do?" I hear you ask. Well imagine the circut is making a
small sinewave on its output and that C1 is huge. How much AC current
flows in R2?
How about specifying what is emittor and collector, and NPN and PNP?
JP
 
B

B

Jan 1, 1970
0
Hank said:
What type of amplifier are you talking about? I can build a class A amplifier
all day long with just one npn transistor.

Hank:

Just an audio amplifier. One wwith considerably more power than can
be had with a single transistor. I just have no clue how you wowuld
pair them, or use more than one b/c of the nature of the transistor.

Thanks!
 
A

Activ8

Jan 1, 1970
0
Don't need transformer. But no one said what kind of amp. If you talking
audio amp, go to the library and look at old old late 60's issues of
"popular electronics" or "radio Electronics" or evne the british "wireless
world".

I might even have one in my file. Basically the output stage is an emitter
follower for the pull up and a common emitter stage for the pull down.
Drive the bases out of phase, and away you go.

del cecchi

That's the other one I was thinking of, but I couldn't say
push-pull, cause it's different and it's not complementary symmetry
or if it is, is not the same as the complimentary symmetry amp that
*does* use a pnp.
 
Top