Small laptop TRANSISTOR amplifier

[cowboybob]

LG,

Came across this site (sort of in your neck of the woods) that might help you as you develop your transistor(s) amp:

https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/experiment/lab/expt5/page1.html

Also, a tube type equivalent (notice the similarities, and the differences):

https://www.angelfire.com/electronic/funwithtubes/Basics_04_Triodes.html

 

[large_ghostman]

Thank Ag I will fire up LT spice tonight . And cowboybob thanks for the links I will read through them.

 

[large_ghostman]

Thank AG I have run it and its working fine , so I have a basic sim of the that circuit to play with. At some point I am going to build the equivalent circuit and one with the chip, then see what the differences are in the sound.
I was going to bread board but that seem's like a bad move, stripboard might do ok for the simple ones but to be honest Iam thinking it might be worth doing PCB's for the test boards, they are not that big or complex so time wise probably ok to make the pcb's, also I am getting out of practice again!

 

[ronv]

Here is the file for the 386. I'm not sure about the resistor in place of the current source. Maybe audio guru can help.

 

[large_ghostman]

Thanks Ron! I like to sim then compare with the actual measurements I make, that is the kind of thing that appeals to my OCD

 

[audioguru]

I fixed the sim of the LM386 by increasing the base current of Q10 and booststrapping it.

 

[4pyros]

I fixed the sim of the LM386 by increasing the base current of Q10 and booststrapping it.

Wow didn't realise till know that you came up with an equivalent LM386 using discrete parts. Because of the file name you gave your circuit.
Good work AG.
LG; you should have some fun with this one. I think it would be cool to compare the chip against the discrete amp side by side.

 

[audioguru]

Wow didn't realise till know that you came up with an equivalent LM386 using discrete parts. Because of the file name you gave your circuit.
Good work AG.

I didn't and it isn't mine. It was in post #24 by RonV. I simply fixed it a little.

 

[4pyros]

I didn't and it isn't mine. It was in post #24 by RonV. I simply fixed it a little.

OK sorry so thanks to RonV.

 

[ronv]

Thanks AG. Very clever.

 

[Nigel Goodwin]

I fixed the sim of the LM386 by increasing the base current of Q10 and booststrapping it.

As an LM386 doesn't have a bootstrap capacitor, presumably (as you would expect) it uses a constant current source instead?.

 

[large_ghostman]

Thank's AG I will apply the changes . I did a 555 timer with the equivalent circuit, it does help you understand it better in some way's. I am also interested in how they compare
My problem is I forget to look at the equivalent circuits in the data sheet's.

 

[audioguru]

As an LM386 doesn't have a bootstrap capacitor, presumably (as you would expect) it uses a constant current source instead?.

I cheated a little.

The LM380 is almost the same as the LM386 and its datasheet shows its current source:

 

[debe]

Just slightly off topic but in post 19 you said you had a friend & your description of him almost fits my son. Its a pitty the school doesn't take on your observations of the needs of disabled people. I like your style Little Ghost man. Just saying.