CCS Biased Class A

davidallancole · 11th February 2006, 03:55 PM

I have been playing with this for a while. What do you guys think. I am going to go to work today to build it and see how it sounds.

Tube_Dude · 11th February 2006, 04:05 PM

Quote:

Originally posted by davidallancole
I have been playing with this for a while. What do you guys think.

The CCS is biased at 6 amps?...

But, some like it hot ...

davidallancole · 11th February 2006, 04:11 PM

Not quite. In the simulation it draws 1.8 A. It puts 12 volts out nicely into 8 ohms, with a 1 V input.

Tube_Dude · 11th February 2006, 04:12 PM

Quote:

Originally posted by davidallancole
Not quite. In the simulation it draws 1.8 A. It puts 12 volts out nicely into 8 ohms, with a 1 V input.

0,6 Volts (one diode drop ) across 0,1 Ohms is 6 Amps...me thinks...

davidallancole · 11th February 2006, 04:19 PM

You must have not noticed the 2.5k resistor after the diodes reducing the current.

Tube_Dude · 11th February 2006, 04:28 PM

Quote:

Originally posted by davidallancole
You must have not noticed the 2.5k resistor after the diodes reducing the current.

That way your CCS is not thermally stable.

Why not simply , to use a 0,3 Ohms emitter resistor..

davidallancole · 11th February 2006, 04:34 PM

I built a rough one of these at work two weeks ago. That 2.5k resistor I used was a pot so I could adjust the bias current. The transistors are on some pretty big heatsinks. They barely come above room temperature.

Tube_Dude · 11th February 2006, 04:36 PM

Quote:

Originally posted by davidallancole
I built a rough one of these at work two weeks ago. That 2.5k resistor I used was a pot so I could adjust the bias current. The transistors are on some pretty big heatsinks. They barely come above room temperature.

That's ok! ...

davidallancole · 11th February 2006, 04:51 PM

I just ran some temperature simulations on PSPICE and it showed as it gets warmer the bias current dropped by a few milliamps.

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11th February 2006, 04:11 PM	#3
davidallancole diyAudio Member Join Date: Nov 2005	Not quite. In the simulation it draws 1.8 A. It puts 12 volts out nicely into 8 ohms, with a 1 V input.

11th February 2006, 04:19 PM	#5
davidallancole diyAudio Member Join Date: Nov 2005	You must have not noticed the 2.5k resistor after the diodes reducing the current.

11th February 2006, 04:34 PM	#7
davidallancole diyAudio Member Join Date: Nov 2005	I built a rough one of these at work two weeks ago. That 2.5k resistor I used was a pot so I could adjust the bias current. The transistors are on some pretty big heatsinks. They barely come above room temperature.

11th February 2006, 04:51 PM	#9
davidallancole diyAudio Member Join Date: Nov 2005	I just ran some temperature simulations on PSPICE and it showed as it gets warmer the bias current dropped by a few milliamps.