Signal amplifier works

[Uncle Steve]

On Fri, Feb 08, 2013 at 09:01:39PM -0800, Jon Kirwan wrote:

On Fri, 08 Feb 2013 21:18:13 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

big snip of everything

You forgot the bootstrap effect >:-}

...Jim Thompson

I didn't miss out on the "Negative Feedback in Audio
Amplifiers" thread. But since this is posted in .basics it
seems appropriate to put on the kid gloves. There's still
plenty of time to add in a bootstrap, too!

I've still got an audio power amp that's better than my somewhat
expensive speakers. Haven't blown that up yet.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Jon Kirwan]

So. I guess the LM383 is the model of the design for this.
Won't do 10V p-p into 2 ohms. Set it up in bridge mode, with
two, maybe? Rochester or Jameco. About $5 each.

Saves more thinking, anyway.

Jon

 

[Jon Kirwan]

On Sat, 09 Feb 2013 13:01:31 -0800, Jon Kirwan
<jonk@infinitefactors.org> wrote:

So. I guess the LM383 is the model of the design for this.
Won't do 10V p-p into 2 ohms. Set it up in bridge mode, with
two, maybe? Rochester or Jameco. About $5 each.

Saves more thinking, anyway.

Of course, there's no spec at 50kHz.

Jon

 

[Uncle Steve]

On Sat, Feb 09, 2013 at 12:56:15AM -0800, Jon Kirwan wrote:

Here's a schematic of something close to what you want. It is
set for around 50kHz (I'm assuming you wanted that) and uses
your three transistor types. If your IN drive is low
impedance, then you don't want it to go more than about
40-50mV p-p. I set the quiescent Vc=7.5V or so. Gain is
40*Iq*R2, but since Iq is about 400uA that's about Av=160. It
will actually be a little lower than that. But it's still
likely to be somewhere around 120 to 140. With about +/-3V
around the 7.5V center, roughly speaking, that would mean no
more than 6vp-p/140 or about 43mVp-p. Which is why I said
40-50mv p-p input at C1.

Ok, thanks for that; it looks interesting. I suppose R5 should be 5
or 10W? (The speaker is only 2 ohms because it is wired in series
with a 2 ohm 10W resistor. Otherwise it has I-don't-know-what
impedance in operation; it's just a ribbon so it's basically 0 ohms to
DC.)

I've even included the ever-popular bootstrap (R7 and C4):

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

Since I've no idea what is driving the thing, except that it
appears to be some kind of low impedance driver if it expects
a 5.1 ohm resistor, then I feel fine stopping here. You may
need to supply that DC path, though, as a resistor divider
and then drive C1 from that.

As I explained in another message, the input is the signal generator
in my DSO. It puts out a 1V signal, and I have no idea what the
impedance of the circuit. I am guessing that the resistor divider you
refer to is what I call a trim pot, and I have a couple different ones
so I should be able to adjust the input signal as you suggest. Now
that you've put it in those terms I now surmise that part of the
signal distortion that I was seeing earlier was a result of misusing
the trim-pot.

I suppose there may be an issue because the signal generator and
probes share a common ground...

The 5.1 ohm resistor is normally wired in series with the speaker when
it is installed in the cabinet and hooked up to the crossover. In
this setup, I'm using 2 ohms because I don't have a 5 ohm resistor
beefy enough to handle the power that was coming out of the original
broken circuit. I assume it is just ballast to give the amplifier
something to push against.

I'll see about wiring this up later this weekend and giving it a try.
It looks simple enough that I ought to be able to figure out what does
what without too much difficulty. 50kHz is the target frequency for
testing and experimentation since my workbench is in a closet and I
don't want to destroy my sanity by working with audible frequencies,
but in practice I may want to use 1 or 2kHz when testing the final
product.

Thanks again!


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sat, Feb 09, 2013 at 02:06:21AM -0800, Jon Kirwan wrote:

On Fri, 08 Feb 2013 19:43:23 -0800, I wrote:

snip

Ignore everything from the base of Q2 and beyond (to the
right.) Ignore C1 for a moment (assume it isn't connected
up.) Just look at R1, R2, Q1, and the +12V supply rail:

+12 +12
| |
| |
| \
| / R2
| \ 5.9k
\ /
/ R1 |
\ 510 |
/ |
| +----Q1 collector ???
| |
| |
| |/c Q1
'------| 2N2222
|>e
|
|
|
gnd

No signal input (obviously.) So you think Q1's collector will
be at 6V? Really?

Let's see. Assume Q1 Vbe=0.7V (within 0.1V, probably) for
now. This means Ib=(12-0.7)/510=22.2mA. Ic, even in the worst
possible case where Q1 is completely saturated and its Vce=0,
would be Ic=12/5.9k=2mA. So the base current is about ten
times the maximum possible collector current. Now THAT is
overdriven, with beta=0.1. You don't see that very often. But
the gist is that Q1's Vce will be driven so close to 0 as to
make no difference at all.

It won't be 6V. The collector is hard-clamped against ground.
snip

I made a mistake reading your values. You are using a 510k,
not 510 for R1. This reduces Ib by a factor of 1000, to
22.2uA. With a beta of 200 or so for the 2n2222, this
suggests a possible Ic=4.44mA. That times a 5.9k ohm
collector resistor, this is a drop of 26.2V across R2. Not
possible at a supply of 12V. Instead, you will see a drop of
about 11.8V with Ic=2mA.

Not as "hard-clampled" as I wrote earlier. But it is still in
saturation and will clip half-cycles. Not so good.

Yeah, I noticed the clipping. In practice, explained in my reply to
your previous post, I was assuming a 'beta' of 50, which may be
trueish of the 2N3055, but is clearly unreasonable for the 2N2222.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sat, Feb 09, 2013 at 10:28:34AM -0700, Jim Thompson wrote:

On Sat, 09 Feb 2013 00:56:15 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

Here's a schematic of something close to what you want. It is
set for around 50kHz (I'm assuming you wanted that) and uses
your three transistor types. If your IN drive is low
impedance, then you don't want it to go more than about
40-50mV p-p. I set the quiescent Vc=7.5V or so. Gain is
40*Iq*R2, but since Iq is about 400uA that's about Av=160. It
will actually be a little lower than that. But it's still
likely to be somewhere around 120 to 140. With about +/-3V
around the 7.5V center, roughly speaking, that would mean no
more than 6vp-p/140 or about 43mVp-p. Which is why I said
40-50mv p-p input at C1.

I've even included the ever-popular bootstrap (R7 and C4):

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

Since I've no idea what is driving the thing, except that it
appears to be some kind of low impedance driver if it expects
a 5.1 ohm resistor, then I feel fine stopping here. You may
need to supply that DC path, though, as a resistor divider
and then drive C1 from that.

Jon

How much power can that deliver to the 2 Ohm load ?:-}

The OP seemed to want 10V P-P across the load. The OP was somewhat
vague on the load, 2 Ohm in series with a "ribbon tweeter". Wonder if
that was a piezoelectric or voice-coil type?

It's a voice coil, and looks like this:

-------------------
| Terminal |
--------+ +--------
+-----+ | | +-----+
| | |R| | |
| | |i| | |
| M | |b| | M |
| a | |b| | a |
| g | |o| | g |
| n | |n| | n |
| e | | | | e |
| t | | | | t |
| | | | | |
| | | | | |
+-----+ | | +-----+
--------+ +--------
| Terminal |
-------------------

I've left out some of the chassis. The two magnets are on the ends of
a cast-aluminum 'horseshoe' that wraps around the back of the driver.
The terminals as shown above are about 2x2x5/16" slabs of aluminum
with a slot machined in the front where the ribbon is affixed with a
small block and Al screw. Physically, the gap between the magnets is
9mm and the ribbon should be slightly smaller. The magnets are
electrically isolated from the terminals. The ribbon is crimped along
its length to facilitate movement.

I'd suggest a class-B structure with some feedback (and some
engineering thought

What he said.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[VWWall]

Uncle Steve wrote:

It's a voice coil, and looks like this:

-------------------
| Terminal |
--------+ +--------
+-----+ | | +-----+
| | |R| | |
| | |i| | |
| M | |b| | M |
| a | |b| | a |
| g | |o| | g |
| n | |n| | n |
| e | | | | e |
| t | | | | t |
| | | | | |
| | | | | |
+-----+ | | +-----+
--------+ +--------
| Terminal |
-------------------

I've left out some of the chassis. The two magnets are on the ends of
a cast-aluminum 'horseshoe' that wraps around the back of the driver.
The terminals as shown above are about 2x2x5/16" slabs of aluminum
with a slot machined in the front where the ribbon is affixed with a
small block and Al screw. Physically, the gap between the magnets is
9mm and the ribbon should be slightly smaller. The magnets are
electrically isolated from the terminals. The ribbon is crimped along
its length to facilitate movement.

This looks exactly like one of the old-time ribbon microphones. I've
never seen them used as an acoustic output device.

--
Virg Wall

 

[Jasen Betts]

On 2013-02-09, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 00:56:15 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:


How much power can that deliver to the 2 Ohm load ?:-}

The OP seemed to want 10V P-P across the load. The OP was somewhat
vague on the load, 2 Ohm in series with a "ribbon tweeter". Wonder if
that was a piezoelectric or voice-coil type?

No, it's a ribbon type.

http://www.visaton.com/en/lexikon/R/8.html

--
⚂⚃ 100% natural

 

[Uncle Steve]

On Sat, Feb 09, 2013 at 10:21:48PM +0000, Jasen Betts wrote:

On 2013-02-09, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
On Sat, 09 Feb 2013 00:56:15 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:


How much power can that deliver to the 2 Ohm load ?:-}

The OP seemed to want 10V P-P across the load. The OP was somewhat
vague on the load, 2 Ohm in series with a "ribbon tweeter". Wonder if
that was a piezoelectric or voice-coil type?

No, it's a ribbon type.

http://www.visaton.com/en/lexikon/R/8.html

Yeah, except in my case, I have used copper leaf (used for gilding) to
fit in the two spares I'm fooling around with. It's incredibly
difficult to work with, such that the shape I impose on as with the
diagram referenced above is so fragile that it can be destroyed by bug
farts or heavy breathing. I may have to locate something slightly
thicker to make it practical.

The bonus with the thin stuff is that it produces incredible detail.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Jim Thompson]

On Sat, 09 Feb 2013 12:17:11 -0800, Jon Kirwan
<jonk@infinitefactors.org> wrote:

On Sat, 09 Feb 2013 12:34:56 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 11:27:27 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

On Sat, 09 Feb 2013 10:28:34 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 00:56:15 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

Here's a schematic of something close to what you want. It is
set for around 50kHz (I'm assuming you wanted that) and uses
your three transistor types. If your IN drive is low
impedance, then you don't want it to go more than about
40-50mV p-p. I set the quiescent Vc=7.5V or so. Gain is
40*Iq*R2, but since Iq is about 400uA that's about Av=160. It
will actually be a little lower than that. But it's still
likely to be somewhere around 120 to 140. With about +/-3V
around the 7.5V center, roughly speaking, that would mean no
more than 6vp-p/140 or about 43mVp-p. Which is why I said
40-50mv p-p input at C1.

I've even included the ever-popular bootstrap (R7 and C4):

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

Since I've no idea what is driving the thing, except that it
appears to be some kind of low impedance driver if it expects
a 5.1 ohm resistor, then I feel fine stopping here. You may
need to supply that DC path, though, as a resistor divider
and then drive C1 from that.

Jon

How much power can that deliver to the 2 Ohm load ?:-}

The OP seemed to want 10V P-P across the load.

No power supply bypassing, either. Anyway, half that at best.
And with plenty of distortion.

The OP was somewhat
vague on the load, 2 Ohm in series with a "ribbon tweeter". Wonder if
that was a piezoelectric or voice-coil type?

I'd suggest a class-B structure with some feedback (and some
engineering thought

Ah, come on. It's got the three transistors in the original
configuration and it has a bootstrap, too!

Now _you_ want a differential pair, current mirrors, a VAS
and a Vbe multiplier, two to perhaps four output BJTs, loop
feedback, speaker reactance compensation, a bipolar power
supply or perhaps a bridge-tied speaker, and THD of 0.1% with
bandwidth to 50kHz? With crafted design thinking to boot?

Yeah, right. It took less than 10 minutes for me to hack up
the above with only a few calculations and then use my custom
program to convert the schematic into ASCII text. I'm sitting
pat at that level of effort to help.

Jon

OK. How much signal does it put into 2 Ohms ?

My guess is that it just peak charges the 3.3uF (C3) which then decays
slowly thru R5 (1K).

Yeah, I see that clearly now. Active one side only. Well, I'm
just an ignorant hobbyist. So I'll chalk up last night to
that, plus a kick in the head. Thanks. Well, at least it was
only a few minutes wasted time last night.

Jon

It wasn't wasted time if you learned something. I know that most here
just think me to be a harsh asshole... but I'm trying to teach
thoughtful analysis of circuits and get folks to drop the hand-waving
BS.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Sat, 09 Feb 2013 16:25:30 -0500, Uncle Steve <stevet810@gmail.com>
wrote:

On Sat, Feb 09, 2013 at 12:56:15AM -0800, Jon Kirwan wrote:
Here's a schematic of something close to what you want. It is
set for around 50kHz (I'm assuming you wanted that) and uses
your three transistor types. If your IN drive is low
impedance, then you don't want it to go more than about
40-50mV p-p. I set the quiescent Vc=7.5V or so. Gain is
40*Iq*R2, but since Iq is about 400uA that's about Av=160. It
will actually be a little lower than that. But it's still
likely to be somewhere around 120 to 140. With about +/-3V
around the 7.5V center, roughly speaking, that would mean no
more than 6vp-p/140 or about 43mVp-p. Which is why I said
40-50mv p-p input at C1.

Ok, thanks for that; it looks interesting. I suppose R5 should be 5
or 10W? (The speaker is only 2 ohms because it is wired in series
with a 2 ohm 10W resistor. Otherwise it has I-don't-know-what
impedance in operation; it's just a ribbon so it's basically 0 ohms to
DC.)

I've even included the ever-popular bootstrap (R7 and C4):

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

Since I've no idea what is driving the thing, except that it
appears to be some kind of low impedance driver if it expects
a 5.1 ohm resistor, then I feel fine stopping here. You may
need to supply that DC path, though, as a resistor divider
and then drive C1 from that.

As I explained in another message, the input is the signal generator
in my DSO. It puts out a 1V signal, and I have no idea what the
impedance of the circuit. I am guessing that the resistor divider you
refer to is what I call a trim pot, and I have a couple different ones
so I should be able to adjust the input signal as you suggest. Now
that you've put it in those terms I now surmise that part of the
signal distortion that I was seeing earlier was a result of misusing
the trim-pot.

I suppose there may be an issue because the signal generator and
probes share a common ground...

The 5.1 ohm resistor is normally wired in series with the speaker when
it is installed in the cabinet and hooked up to the crossover. In
this setup, I'm using 2 ohms because I don't have a 5 ohm resistor
beefy enough to handle the power that was coming out of the original
broken circuit. I assume it is just ballast to give the amplifier
something to push against.

I'll see about wiring this up later this weekend and giving it a try.
It looks simple enough that I ought to be able to figure out what does
what without too much difficulty. 50kHz is the target frequency for
testing and experimentation since my workbench is in a closet and I
don't want to destroy my sanity by working with audible frequencies,
but in practice I may want to use 1 or 2kHz when testing the final
product.

Thanks again!


Regards,

Uncle Steve

Here's what I was driving at...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier.pdf

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jon Kirwan]

On Sat, 09 Feb 2013 17:44:32 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 12:17:11 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

On Sat, 09 Feb 2013 12:34:56 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 11:27:27 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

On Sat, 09 Feb 2013 10:28:34 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 09 Feb 2013 00:56:15 -0800, Jon Kirwan
jonk@infinitefactors.org> wrote:

Here's a schematic of something close to what you want. It is
set for around 50kHz (I'm assuming you wanted that) and uses
your three transistor types. If your IN drive is low
impedance, then you don't want it to go more than about
40-50mV p-p. I set the quiescent Vc=7.5V or so. Gain is
40*Iq*R2, but since Iq is about 400uA that's about Av=160. It
will actually be a little lower than that. But it's still
likely to be somewhere around 120 to 140. With about +/-3V
around the 7.5V center, roughly speaking, that would mean no
more than 6vp-p/140 or about 43mVp-p. Which is why I said
40-50mv p-p input at C1.

I've even included the ever-popular bootstrap (R7 and C4):

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

Since I've no idea what is driving the thing, except that it
appears to be some kind of low impedance driver if it expects
a 5.1 ohm resistor, then I feel fine stopping here. You may
need to supply that DC path, though, as a resistor divider
and then drive C1 from that.

Jon

How much power can that deliver to the 2 Ohm load ?:-}

The OP seemed to want 10V P-P across the load.

No power supply bypassing, either. Anyway, half that at best.
And with plenty of distortion.

The OP was somewhat
vague on the load, 2 Ohm in series with a "ribbon tweeter". Wonder if
that was a piezoelectric or voice-coil type?

I'd suggest a class-B structure with some feedback (and some
engineering thought

Ah, come on. It's got the three transistors in the original
configuration and it has a bootstrap, too!

Now _you_ want a differential pair, current mirrors, a VAS
and a Vbe multiplier, two to perhaps four output BJTs, loop
feedback, speaker reactance compensation, a bipolar power
supply or perhaps a bridge-tied speaker, and THD of 0.1% with
bandwidth to 50kHz? With crafted design thinking to boot?

Yeah, right. It took less than 10 minutes for me to hack up
the above with only a few calculations and then use my custom
program to convert the schematic into ASCII text. I'm sitting
pat at that level of effort to help.

Jon

OK. How much signal does it put into 2 Ohms ?

My guess is that it just peak charges the 3.3uF (C3) which then decays
slowly thru R5 (1K).

Yeah, I see that clearly now. Active one side only. Well, I'm
just an ignorant hobbyist. So I'll chalk up last night to
that, plus a kick in the head. Thanks. Well, at least it was
only a few minutes wasted time last night.

Jon

It wasn't wasted time if you learned something. I know that most here
just think me to be a harsh asshole... but I'm trying to teach
thoughtful analysis of circuits and get folks to drop the hand-waving
BS.

...Jim Thompson

Yes, I learned to not write at night. hehe. I already KNEW
what you had to rub my nose into, though. I just wasn't
engaged in considering all the issues. Had blinders on. Oh,
well. There is a lesson there, too.

Jon

 

[Uncle Steve]

On Sat, Feb 09, 2013 at 12:56:15AM -0800, Jon Kirwan wrote:

: ,---------------+---------------+------------+----------,
: | | | | |
: | | | | |
: \ \ | | ---
: / R4 / R2 | | - V1
: \ 150k \ 10k | | --- 12
: / / | | -
: | C1 | |/c Q3 | |
: | || .047u +-------------| 2N2222 | |
: IN------------||---, | |>e | |
: | || | | | | gnd
: | | | | |
: | | | | |/c Q2
: | R7 | |/c Q1 '-+--------| 2N3055
: +---/\/\---+--| 2N2222 | |>e
: | 220k |>e | |
: | C4 | \ |
: | ||.047u | / R6 | C3
: +-------||------+ \ 2.2k | || 3.3u
: | || +-------, / +----||-----,
: | | | | | || |
: \ \ | | | |
: / R3 / R1 --- C2 gnd \ |
: \ 33k \ 2.7k --- .47u / R5 )| /
: / / | \ 1k )|/ speaker
: | | | / )|\ 2 ohm
: | | | | )| \
: gnd gnd gnd | |
: gnd |
: gnd

I've been looking at this circuit, and I don't see how the input to
the base of Q3 can be reasonable unless the output of Q1 is kept so
low that it doesn't go over a volt or so, in which case what's the
point of having it?

In the previous circuit I was using, the intent of Q2 (Q3 in your
circuit) was to boost the current of the signal from Q1, however I was
apparently working with bogus information from a web-page that posted
circuits that don't work (i.e. Figure 16).

Are you sure you didn't rattle a bunch of components in a metaphorical
box and then open it to produce the above circuit?


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sun, Feb 10, 2013 at 11:28:24AM -0700, Jim Thompson wrote:

On Sat, 09 Feb 2013 17:51:18 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

[snip]

Here's what I was driving at...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier.pdf

...Jim Thompson

Further amusing myself...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier_revB.pdf

Far simpler, but slightly less swing capability.

You must admit that as amusing as it may be (to you), it mitigates the
threat that a civil discussion will result from either 'design'.

It makes no difference that people with your values dominate the
newsgroups; only that you seem to feel that the world begins and ends
with you. The rest of us are only a minor inconvenience to that
worldview, I suppose.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Sun, Feb 10, 2013 at 01:49:20PM -0500, Phil Hobbs wrote:

On 2/10/2013 10:44 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 10:18:13AM -0500, Phil Hobbs wrote:
On 2/9/2013 9:55 PM, John Larkin wrote:
On Fri, 08 Feb 2013 14:14:08 -0500, Uncle Steve <stevet810@gmail.com
wrote:

... unless there is no signal at the input.

I started with some information at the following two URLS:

http://www.mysticmarvels.com/amplifier.html
http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html

Sorry, they are both hacks and idiots, the first one being the worst.

Yup, both full of Bad Info presented with confidence. The first guy is
smarmy besides, coming over all superior about current flow vs electron
flow, as if it mattered for solid-state circuit design.

That little tidbit is useful. As electrons are the medium of
electronic signal propagation, it's helpful to know what's actually
going on in the wires. Counter-intuitive concepts like that are
exactly the sort of thing that make science difficult for kids. An
exemplar is the view of the Earth as the center of the universe, as
was common knowledge prior to the Copernican revolution.

It's a good thing to know, but reversing the directions of all the
arrows in his diagrams is going to confuse people terminally when they
get to real circuit design. The main point of drawing diagrams so that
current flows generally downward and to the right is so that people
don't get confused, and to reduce the number of minus signs in the
algebra, which of course are a common source of blunders.

The less obvious advantage to the current convention is that it makes
electronic diagrams more amenable to stand-in as loose metaphor for
life, or living, but it is difficult to explain since 'living' in this
context is a religious concept subject to the usual prohibitions on
open discussion or analysis.

Counterfactual concepts make real understanding unnecessarily
difficult. The fact that electronic circuits are presented with the
assumption that charge flows from positive to negative poles obscures
the idea that it is the electrical potential for the flow of electrons
that is significant at any given point in a circuit. I don't doubt
that the terminology in common use could be less confusing.

Do you have an example of a solid-state circuit accessible to a beginner
where it matters what the carrier polarity is? Holes are slower than
electrons in almost every material I can think of, but they look like
perfectly good positive charge carriers in all other respects.


The first URL goes through the process of building a high-gain
amplifier, and it works O.K. with the exception that there is no
power. The second URL goes into more detail and shows how to deliver
some power to the speaker as in figure 16. I have different parts on
hand, and I am working with a 12V supply instead of 9V as in the first
URL. Since I am looking to deliver big chunky volts to my speaker,
I went ahead and modified Figure 16 and the example in the first URL
to obtain the following circuit:


12V +---+----------+----------+ R1 = 510K
| | | | R2 = 5.9K
| > R2 > R3 | R3 = 220
R1 > < < | C1 = 1uF
| | | Q1, Q2 = 2N2222
| +-- | | Q3 = 2N3055
input | | \ b |c |
o---||-+-(Q1) -----(Q2) -----(Q3)
C1 | |e / |
1uf | --- SPKR
| |
| |
o----------+---------------------+

SPKR is a ribbon tweeter with a 2 Ohm, 10 Watt resistor in series.

Yikes, Beta bias! DC through the voice coil!



That looks a lot like a circuit that I built when I was 10, out of a
book of projects (that would have been early 1970). It sorta worked,
kinda, but ate batteries like mad. (It used a TR01C TO-3 package
germanium transistor, made by International Rectifier. It also had a
carbon mic so it didn't need a preamp.)

I'll be better off when I internalize the details of how transistors
work in various configurations, but at the moment the concepts are
still a little fuzzy.

Sure, it takes everybody awhile--they're nontrivial devices. It's
easier to get right if you think of transistors as mostly
voltage-controlled rather than current-controlled. That's closer to the
physics, and will also protect you against doing beta-dependent circuits
like the above and the ones in reference #2.

Base current isn't a necessary feature of transistor behaviour--you can
get transistors with betas ranging from about 5 to several thousand, and
the beta of a single device can easily vary over a 3:1 range, depending
on collector current. On the other hand, transconductance is almost
identical for every transistor at a given collector current, and comes
right out of the simplest version of the device physics (the Ebers-Moll
model).

Monkeys armed with typewriters have mastered basic analog electronics,
so I ought to be able to get there as well. It would be helpful if
there were less disinformation or outright lies in the way, however.
Some people seem strangely committed to making learning as difficult
as possible. I wonder why that is.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Phil Hobbs]

On 02/11/2013 04:43 AM, Uncle Steve wrote:

On Sun, Feb 10, 2013 at 01:49:20PM -0500, Phil Hobbs wrote:
On 2/10/2013 10:44 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 10:18:13AM -0500, Phil Hobbs wrote:
On 2/9/2013 9:55 PM, John Larkin wrote:
On Fri, 08 Feb 2013 14:14:08 -0500, Uncle Steve<stevet810@gmail.com
wrote:

... unless there is no signal at the input.

I started with some information at the following two URLS:

http://www.mysticmarvels.com/amplifier.html
http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html

Sorry, they are both hacks and idiots, the first one being the worst.

Yup, both full of Bad Info presented with confidence. The first guy is
smarmy besides, coming over all superior about current flow vs electron
flow, as if it mattered for solid-state circuit design.

That little tidbit is useful. As electrons are the medium of
electronic signal propagation, it's helpful to know what's actually
going on in the wires. Counter-intuitive concepts like that are
exactly the sort of thing that make science difficult for kids. An
exemplar is the view of the Earth as the center of the universe, as
was common knowledge prior to the Copernican revolution.

It's a good thing to know, but reversing the directions of all the
arrows in his diagrams is going to confuse people terminally when they
get to real circuit design. The main point of drawing diagrams so that
current flows generally downward and to the right is so that people
don't get confused, and to reduce the number of minus signs in the
algebra, which of course are a common source of blunders.

The less obvious advantage to the current convention is that it makes
electronic diagrams more amenable to stand-in as loose metaphor for
life, or living, but it is difficult to explain since 'living' in this
context is a religious concept subject to the usual prohibitions on
open discussion or analysis.

Counterfactual concepts make real understanding unnecessarily
difficult. The fact that electronic circuits are presented with the
assumption that charge flows from positive to negative poles obscures
the idea that it is the electrical potential for the flow of electrons
that is significant at any given point in a circuit. I don't doubt
that the terminology in common use could be less confusing.

Do you have an example of a solid-state circuit accessible to a beginner
where it matters what the carrier polarity is? Holes are slower than
electrons in almost every material I can think of, but they look like
perfectly good positive charge carriers in all other respects.


The first URL goes through the process of building a high-gain
amplifier, and it works O.K. with the exception that there is no
power. The second URL goes into more detail and shows how to deliver
some power to the speaker as in figure 16. I have different parts on
hand, and I am working with a 12V supply instead of 9V as in the first
URL. Since I am looking to deliver big chunky volts to my speaker,
I went ahead and modified Figure 16 and the example in the first URL
to obtain the following circuit:


12V +---+----------+----------+ R1 = 510K
| | | | R2 = 5.9K
|> R2> R3 | R3 = 220
R1> < < | C1 = 1uF
| | | Q1, Q2 = 2N2222
| +-- | | Q3 = 2N3055
input | | \ b |c |
o---||-+-(Q1) -----(Q2) -----(Q3)
C1 | |e / |
1uf | --- SPKR
| |
| |
o----------+---------------------+

SPKR is a ribbon tweeter with a 2 Ohm, 10 Watt resistor in series.

Yikes, Beta bias! DC through the voice coil!



That looks a lot like a circuit that I built when I was 10, out of a
book of projects (that would have been early 1970). It sorta worked,
kinda, but ate batteries like mad. (It used a TR01C TO-3 package
germanium transistor, made by International Rectifier. It also had a
carbon mic so it didn't need a preamp.)

I'll be better off when I internalize the details of how transistors
work in various configurations, but at the moment the concepts are
still a little fuzzy.

Sure, it takes everybody awhile--they're nontrivial devices. It's
easier to get right if you think of transistors as mostly
voltage-controlled rather than current-controlled. That's closer to the
physics, and will also protect you against doing beta-dependent circuits
like the above and the ones in reference #2.

Base current isn't a necessary feature of transistor behaviour--you can
get transistors with betas ranging from about 5 to several thousand, and
the beta of a single device can easily vary over a 3:1 range, depending
on collector current. On the other hand, transconductance is almost
identical for every transistor at a given collector current, and comes
right out of the simplest version of the device physics (the Ebers-Moll
model).

Monkeys armed with typewriters have mastered basic analog electronics,
so I ought to be able to get there as well. It would be helpful if
there were less disinformation or outright lies in the way, however.
Some people seem strangely committed to making learning as difficult
as possible. I wonder why that is.

They're all conspiring against you.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Jim Thompson]

On Mon, 11 Feb 2013 04:35:14 -0500, Uncle Steve <stevet810@gmail.com>
wrote:

On Sun, Feb 10, 2013 at 11:28:24AM -0700, Jim Thompson wrote:
On Sat, 09 Feb 2013 17:51:18 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

[snip]

Here's what I was driving at...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier.pdf

...Jim Thompson

Further amusing myself...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier_revB.pdf

Far simpler, but slightly less swing capability.

You must admit that as amusing as it may be (to you), it mitigates the
threat that a civil discussion will result from either 'design'.

How does it do that? The 'designs' _were_ discussed and serious flaws
shown.

It makes no difference that people with your values dominate the
newsgroups;

What values are those? No BS or hand-waving?

only that you seem to feel that the world begins and ends
with you. The rest of us are only a minor inconvenience to that
worldview, I suppose.

You're one sick puppy. You're never going to learn circuits if your
"world" is based on the attitude that your circuit works because you
wish it so.

Regards,

Uncle Steve

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Mon, 11 Feb 2013 11:21:40 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 02/11/2013 04:43 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 01:49:20PM -0500, Phil Hobbs wrote:
On 2/10/2013 10:44 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 10:18:13AM -0500, Phil Hobbs wrote:
On 2/9/2013 9:55 PM, John Larkin wrote:
On Fri, 08 Feb 2013 14:14:08 -0500, Uncle Steve<stevet810@gmail.com
wrote:

... unless there is no signal at the input.

I started with some information at the following two URLS:

http://www.mysticmarvels.com/amplifier.html
http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html

Sorry, they are both hacks and idiots, the first one being the worst.

Yup, both full of Bad Info presented with confidence. The first guy is
smarmy besides, coming over all superior about current flow vs electron
flow, as if it mattered for solid-state circuit design.

That little tidbit is useful. As electrons are the medium of
electronic signal propagation, it's helpful to know what's actually
going on in the wires. Counter-intuitive concepts like that are
exactly the sort of thing that make science difficult for kids. An
exemplar is the view of the Earth as the center of the universe, as
was common knowledge prior to the Copernican revolution.

It's a good thing to know, but reversing the directions of all the
arrows in his diagrams is going to confuse people terminally when they
get to real circuit design. The main point of drawing diagrams so that
current flows generally downward and to the right is so that people
don't get confused, and to reduce the number of minus signs in the
algebra, which of course are a common source of blunders.

The less obvious advantage to the current convention is that it makes
electronic diagrams more amenable to stand-in as loose metaphor for
life, or living, but it is difficult to explain since 'living' in this
context is a religious concept subject to the usual prohibitions on
open discussion or analysis.

Counterfactual concepts make real understanding unnecessarily
difficult. The fact that electronic circuits are presented with the
assumption that charge flows from positive to negative poles obscures
the idea that it is the electrical potential for the flow of electrons
that is significant at any given point in a circuit. I don't doubt
that the terminology in common use could be less confusing.

Do you have an example of a solid-state circuit accessible to a beginner
where it matters what the carrier polarity is? Holes are slower than
electrons in almost every material I can think of, but they look like
perfectly good positive charge carriers in all other respects.


The first URL goes through the process of building a high-gain
amplifier, and it works O.K. with the exception that there is no
power. The second URL goes into more detail and shows how to deliver
some power to the speaker as in figure 16. I have different parts on
hand, and I am working with a 12V supply instead of 9V as in the first
URL. Since I am looking to deliver big chunky volts to my speaker,
I went ahead and modified Figure 16 and the example in the first URL
to obtain the following circuit:


12V +---+----------+----------+ R1 = 510K
| | | | R2 = 5.9K
|> R2> R3 | R3 = 220
R1> < < | C1 = 1uF
| | | Q1, Q2 = 2N2222
| +-- | | Q3 = 2N3055
input | | \ b |c |
o---||-+-(Q1) -----(Q2) -----(Q3)
C1 | |e / |
1uf | --- SPKR
| |
| |
o----------+---------------------+

SPKR is a ribbon tweeter with a 2 Ohm, 10 Watt resistor in series.

Yikes, Beta bias! DC through the voice coil!



That looks a lot like a circuit that I built when I was 10, out of a
book of projects (that would have been early 1970). It sorta worked,
kinda, but ate batteries like mad. (It used a TR01C TO-3 package
germanium transistor, made by International Rectifier. It also had a
carbon mic so it didn't need a preamp.)

I'll be better off when I internalize the details of how transistors
work in various configurations, but at the moment the concepts are
still a little fuzzy.

Sure, it takes everybody awhile--they're nontrivial devices. It's
easier to get right if you think of transistors as mostly
voltage-controlled rather than current-controlled. That's closer to the
physics, and will also protect you against doing beta-dependent circuits
like the above and the ones in reference #2.

Base current isn't a necessary feature of transistor behaviour--you can
get transistors with betas ranging from about 5 to several thousand, and
the beta of a single device can easily vary over a 3:1 range, depending
on collector current. On the other hand, transconductance is almost
identical for every transistor at a given collector current, and comes
right out of the simplest version of the device physics (the Ebers-Moll
model).

Monkeys armed with typewriters have mastered basic analog electronics,
so I ought to be able to get there as well. It would be helpful if
there were less disinformation or outright lies in the way, however.
Some people seem strangely committed to making learning as difficult
as possible. I wonder why that is.


They're all conspiring against you.

Cheers

Phil Hobbs

Yep. THAT'S what it is >:-}

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Uncle Steve]

On Mon, Feb 11, 2013 at 09:37:31AM -0700, Jim Thompson wrote:

On Mon, 11 Feb 2013 04:35:14 -0500, Uncle Steve <stevet810@gmail.com
wrote:

On Sun, Feb 10, 2013 at 11:28:24AM -0700, Jim Thompson wrote:
On Sat, 09 Feb 2013 17:51:18 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

[snip]

Here's what I was driving at...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier.pdf

...Jim Thompson

Further amusing myself...

http://www.analog-innovations.com/SED/Uncle_Steve_Amplifier_revB.pdf

Far simpler, but slightly less swing capability.

You must admit that as amusing as it may be (to you), it mitigates the
threat that a civil discussion will result from either 'design'.

How does it do that? The 'designs' _were_ discussed and serious flaws
shown.

The point is that your circuits appear to be presented to show how
witty you are.

It makes no difference that people with your values dominate the
newsgroups;

What values are those? No BS or hand-waving?

No meaningful discussion with 'outsiders'. I see a great deal of
snarky commentary, but little of substance regarding what I have
written. Your level of engagement is limited to posting your circuits
and commentary on that, at a level that is exclusive to the 'noobs'.

only that you seem to feel that the world begins and ends
with you. The rest of us are only a minor inconvenience to that
worldview, I suppose.

You're one sick puppy. You're never going to learn circuits if your
"world" is based on the attitude that your circuit works because you
wish it so.

Classic straw-man argument. Show where I asserted any such sentiment.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

 

[Uncle Steve]

On Mon, Feb 11, 2013 at 11:21:40AM -0500, Phil Hobbs wrote:

On 02/11/2013 04:43 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 01:49:20PM -0500, Phil Hobbs wrote:
On 2/10/2013 10:44 AM, Uncle Steve wrote:
On Sun, Feb 10, 2013 at 10:18:13AM -0500, Phil Hobbs wrote:
On 2/9/2013 9:55 PM, John Larkin wrote:
On Fri, 08 Feb 2013 14:14:08 -0500, Uncle Steve<stevet810@gmail.com
wrote:

... unless there is no signal at the input.

I started with some information at the following two URLS:

http://www.mysticmarvels.com/amplifier.html
http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html

Sorry, they are both hacks and idiots, the first one being the worst.

Yup, both full of Bad Info presented with confidence. The first guy is
smarmy besides, coming over all superior about current flow vs electron
flow, as if it mattered for solid-state circuit design.

That little tidbit is useful. As electrons are the medium of
electronic signal propagation, it's helpful to know what's actually
going on in the wires. Counter-intuitive concepts like that are
exactly the sort of thing that make science difficult for kids. An
exemplar is the view of the Earth as the center of the universe, as
was common knowledge prior to the Copernican revolution.

It's a good thing to know, but reversing the directions of all the
arrows in his diagrams is going to confuse people terminally when they
get to real circuit design. The main point of drawing diagrams so that
current flows generally downward and to the right is so that people
don't get confused, and to reduce the number of minus signs in the
algebra, which of course are a common source of blunders.

The less obvious advantage to the current convention is that it makes
electronic diagrams more amenable to stand-in as loose metaphor for
life, or living, but it is difficult to explain since 'living' in this
context is a religious concept subject to the usual prohibitions on
open discussion or analysis.

Counterfactual concepts make real understanding unnecessarily
difficult. The fact that electronic circuits are presented with the
assumption that charge flows from positive to negative poles obscures
the idea that it is the electrical potential for the flow of electrons
that is significant at any given point in a circuit. I don't doubt
that the terminology in common use could be less confusing.

Do you have an example of a solid-state circuit accessible to a beginner
where it matters what the carrier polarity is? Holes are slower than
electrons in almost every material I can think of, but they look like
perfectly good positive charge carriers in all other respects.


The first URL goes through the process of building a high-gain
amplifier, and it works O.K. with the exception that there is no
power. The second URL goes into more detail and shows how to deliver
some power to the speaker as in figure 16. I have different parts on
hand, and I am working with a 12V supply instead of 9V as in the first
URL. Since I am looking to deliver big chunky volts to my speaker,
I went ahead and modified Figure 16 and the example in the first URL
to obtain the following circuit:


12V +---+----------+----------+ R1 = 510K
| | | | R2 = 5.9K
|> R2> R3 | R3 = 220
R1> < < | C1 = 1uF
| | | Q1, Q2 = 2N2222
| +-- | | Q3 = 2N3055
input | | \ b |c |
o---||-+-(Q1) -----(Q2) -----(Q3)
C1 | |e / |
1uf | --- SPKR
| |
| |
o----------+---------------------+

SPKR is a ribbon tweeter with a 2 Ohm, 10 Watt resistor in series.

Yikes, Beta bias! DC through the voice coil!



That looks a lot like a circuit that I built when I was 10, out of a
book of projects (that would have been early 1970). It sorta worked,
kinda, but ate batteries like mad. (It used a TR01C TO-3 package
germanium transistor, made by International Rectifier. It also had a
carbon mic so it didn't need a preamp.)

I'll be better off when I internalize the details of how transistors
work in various configurations, but at the moment the concepts are
still a little fuzzy.

Sure, it takes everybody awhile--they're nontrivial devices. It's
easier to get right if you think of transistors as mostly
voltage-controlled rather than current-controlled. That's closer to the
physics, and will also protect you against doing beta-dependent circuits
like the above and the ones in reference #2.

Base current isn't a necessary feature of transistor behaviour--you can
get transistors with betas ranging from about 5 to several thousand, and
the beta of a single device can easily vary over a 3:1 range, depending
on collector current. On the other hand, transconductance is almost
identical for every transistor at a given collector current, and comes
right out of the simplest version of the device physics (the Ebers-Moll
model).

Monkeys armed with typewriters have mastered basic analog electronics,
so I ought to be able to get there as well. It would be helpful if
there were less disinformation or outright lies in the way, however.
Some people seem strangely committed to making learning as difficult
as possible. I wonder why that is.


They're all conspiring against you.

Only the retard, righttards, and related degenerates and defectives.
Oftentimes they believe (with no evidence) that their mindset is
exclusive to the world's population, but in actual point of fact they
pretend that sensible, rational, normal folk don't exist and only
those with their special brand of prejudice are 'people'. They are
easily identifiable by their myopic insistance that reality must
conform to their view of it, or at least what little of it they
acknowledge.

It's all so tiresome. Greg Egan once wrote of a hypothetical
terrorist group described as "anthrocosmologists" who bear a striking
resemblance to such persons, who impute anthropic principles to
existence a priori -- which is necessarily the opposite to the idea of
undertaking observation to deduce or infer principles of existence.
The sick joke is that this retrograde method of apprehending reality
is called 'knowing' among people of that sort. To 'know' is to bring
an aspect of reality into existence, in contrast to the usual process
of knowledge acquisition normal to scientific pursuit. Losers.


Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin