Basically yes, but I would also add a 4K7 resistor from the emitter to ground as well as the load. This makes sure there is always a path to ground even when it is not connected to a load.
4K or 4.7K?
4K7 is shorthand for 4.7K. Saves typing a dot. Either would work. 4.7K ohm resistors are common.
Figured. Here is the final schematic I drew up:
Next Ill see if I can translate this correctly onto a breadboard (couple of breadboards :-)) and then Id like to make the calculations to see what I should expect.
Does that sound right?
Here it is on the breadboard:
(top part) = Vout to Transistor
(nxt dwn) = Vout-Vin interconnection
(nxt dwn) = opamp
(bottom) = mic entry-cap
On the left +/- rails I have GND with green wires on the black-rail
On the rt +/- rails I have +9V on red-rail and -9V on black-rail
Does that sound right?
No.
The transistor is all shorted out.
The base goes to the op-amp output no where else.
The 4K7 is missing
You have changed the configuration from the origional diagram.
R4 and R5 are in parallel. Remove one of them.
Being in parallel is wrong because why?
Because it is a waste of a resistor. Two identical resistors in parallel is the same as having just one resistor at half the value.
In that last diagram you seem to have shorted out the speaker.
you mean shorted because there is nothing between it and Ground?
But then how can I not have it be in parallel with the Emitter resistor-to-ground you said I should add?
But then how can I not have it be in parallel with the Emitter resistor-to-ground you said I should add?
Are you telling me that in reply #46 R4 was the speaker? If so why was it given a value of 4K7? I thought we had established it was 32R.
Oh! Yeah, I just dont know how to draw a speaker in ltspice. I dont have that component. Ok, so you want to see the speaker as a 32Ω load, which is what it is. But you said you wanted a:
"4K7 R from emitter to ground as well as the load. "
I understood that as adding a 4K7 R between Emitter and Ground and between Speaker and Ground.
So like this:
Yes that is better. The R6 resistor is so that things still work correctly when the speaker is disconnected.
Well I can hear some rattling sound out of the speaker when I move a resistor which seems loose (R3 mic+toVcc+). Probably just noise. So to the schematic...Im assuming it can be calculated, what the voltage and current flow should be at each point in the circuit, right?
Will LTSpice just tell me and then I can check those values against what I see on the board?
Im assuming it can be calculated, what the voltage and current flow should be at each point in the circuit, right?
Yes
Will LTSpice just tell me and then I can check those values against what I see on the board?
Yes
Here are my LTSpice results:
Vin (Signal) = 30mV
Vp ~ 0.18mV
Vn ~ 80mV
Vout ~ 8.95V
Vaudioout ~ 8.05V
BJT = 2.5mA
R1 & R5 (negative feedback Rs) ~ 79uA
R2 ~ 0 mA
R3 ~ 1.3mA
Speaker ~ 250mA
R6 ~ 0mA
C1: Current is in the fA.
Here is the image:
I can see the 30mV signal amplified to 8.95V and the current bumped from 2.5mA to 250mA. Seems logical.
But Im only getting 0.48V at Vout in the circuit 
ChrisTenone:
4K7 is shorthand for 4.7K. Saves typing a dot. Either would work. 4.7K ohm resistors are common.
It isn't shorthand, it is because if you print or write 4.7k on a schematic, it doesn't take much to either mistake the dot for a bit of smudge, or it might really be 47k but you mistake a bit of smudge for a dot.
4k7 is much harder to mistake for another value.
That is a terrible way to drive a speaker. You will only see the positive going cycle on the speaker, as half of the waveform is clipped. That circuit only has the ability to source current into the speaker, not sink it.
You want something more like this:
By the way, is the center connection between the two 9V batteries connected to circuit ground?
polymorph:
It isn't shorthand, it is because if you print or write 4.7k on a schematic, it doesn't take much to either mistake the dot for a bit of smudge, or it might really be 47k but you mistake a bit of smudge for a dot.4k7 is much harder to mistake for another value.
That's the history. Digital files don't smudge.