[David White]

I posted this to sci.eelctronics.basic, where it probably belongs, but
things seem a bit quiet over there at the moment.

Based on previous advice from the groups, I have attempted
to revise our circuit utilizing a complimentary pair, and diodes to
establish a 1.4V DC offset between the two output signals.

Here is the schematic, if anyone would please be able to comment on
mistakes.

http://www.4shared.com/photo/-Uflsi2Z/Dual-Emitter-Follower.html

If this sounds familliar, there are several of us cooperating on the
same project, none obviously any more gifted than the other.

Thank you,

David White

 

[mike]

I posted this to sci.eelctronics.basic, where it probably belongs, but
things seem a bit quiet over there at the moment.

Based on previous advice from the groups, I have attempted
to revise our circuit utilizing a complimentary pair, and diodes to
establish a 1.4V DC offset between the two output signals.

Here is the schematic, if anyone would please be able to comment on
mistakes.

http://www.4shared.com/photo/-Uflsi2Z/Dual-Emitter-Follower.html

If this sounds familliar, there are several of us cooperating on the
same project, none obviously any more gifted than the other.

Thank you,

David White

+1 on the "what are you trying to accomplish?

What are the characteristics of the two different inputs?
And what does it mean to have an offset between two different "audio
sine wave" inputs that are half-wave rectified?
And how does the base-emitter reverse breakdown voltage compare the the
input signals?
And what do the batteries do?
If you draw a box around the top half and apply norton's theorm,
the output current has to be less than the input current by the amount
of diode current.

 

[David White]

I don't see how that can work. The floating battery, and D1, mean that
the upper-circuit power rails (namely the B1 terminals [1] ) will
flail all over the place as a function of the input and output
currents. Looks like you'll zener the base of Q1 on negative input
swings, adding to the fun.

What are you trying to do?

[1] A battery is a "B", not a "BT"

If I understand correctly, John, if the diodes were removed the
circuit would work.

The question is, why are they there?

As I attempted to indicate on the diagram, the two outputs are meant
to be floating (dual single wire system), one above and one below the
grounded battery common by 0.7V.

IOW one swings 0.7V positive to 9V positive. The other is 9V negative
to 0.7V negative.

Putting aside convention, for the moment, the unique point is NOT to
have them referenced to ground. Perhaps we are going about it the
wrong way, but we seem to have tried everything else.

I would like to go ahead and build the circuit if anyone can tell me
how to give it half a chance.

How about replacing the diodes with +/- 5V voltage regulators? We
could use +/- 12VDC rails to compensate for the voltage loss.

David

 

[miso]

It looks to me like you are trying to make a class B or class AB output
driver. Why not look at those circuits first before rolling your own?

 

[David White]

What is it supposed to do?

With diodes removed, I assume one output would swing between +9 and 0
Volts, and the other -9 and 0 volts. Can we say that much will work?

What is the bigger problem you are trying to solve>

The intended circuit is a learning exercise, and, as yet, has no
practical application.

The only object is to output two identical signals with no direct
ground reference to each other or the supply; one being offset
positively from ground and the other negatively.

Not being a conventional approach, it appears difficult to get one's
head around. But I assume it is possible ... somehow.

David

 

[Phil Allison]

"David White"

The intended circuit is a learning exercise, and, as yet, has no
practical application.

** You have no knowledge of electronics at all - do you ?

The only object is to output two identical signals with no direct
ground reference to each other or the supply;

** Only way to do that involves isolation transformers.

one being offset
positively from ground and the other negatively.

** That implies they ARE referenced to each other.

You show the inputs with a common ground too - contradicting your own
words.

Not being a conventional approach,

** No, it is a fuckwit approach.


.... Phil