Power amp with current output, F1 competitor (kidding)

PMA · 25th September 2007, 08:09 AM

Guys,

I have taken note of the F1 popularity. If anyone of you wanted to play with current output amplifier, here is the circuit hint. It is up to you to calculate part values

.

Best,
Pavel

destroyer X · 25th September 2007, 08:17 AM

Please, instruct us how to control the off set and suggest some values to this schematic.

Was one schematic that our forum friend Ostry provided me and i could not control the off set...not exactly this one you suggest..but alike related the topology.

regards,

Carlos

Vix · 25th September 2007, 08:20 AM

And where is the nice paper, with all the explanations?

Ipanema · 25th September 2007, 08:30 AM

Quote:

control the off set

You might want to use a DC servo.

PMA · 25th September 2007, 09:06 AM

Hi Carlos,

yes, the DC offset depends on sameness of N and P halves. It is not that bad, though, even with change of

temperature. In case you disconnect the load, the DC increases substantially. Also, for higher ohm load the DC

increases. And gain increases with load, this is a current output amplifier.

The DC servo injecting current into input node would be the cure, as Ipanema has mentioned

Best,
Pavel

DarkOne · 25th September 2007, 10:36 AM

You should also move resistors from drain of output transistors to their source to improve linearity.

PMA · 25th September 2007, 10:42 AM

No, unless you want the amplifier to blow.

And distortion s HIGHER with resistors moved into sources!!

PMA · 25th September 2007, 11:48 AM

Hereby something with component values. Iddle current is 1.5A. Transadmitance is about 0.725A output current to 1V input voltage difference (0.725A/V).

PMA · 25th September 2007, 12:16 PM

+ DC offset compensation

lumanauw · 25th September 2007, 01:58 PM

Quote:

No, unless you want the amplifier to blow.

Why is that?

25th September 2007, 08:17 AM	#2
destroyer X diyAudio Member Join Date: Feb 2004 Location: Recife - Brasil Northeast	I have tried once...but i had problems with off set. Please, instruct us how to control the off set and suggest some values to this schematic. Was one schematic that our forum friend Ostry provided me and i could not control the off set...not exactly this one you suggest..but alike related the topology. regards, Carlos __________________ Try to build an amplifier folks ... it is pure adrenaline!.. when not work first time, then becomes a nice challenge...and we usually overcome the trouble... and we feel very well to be mastering the machine.

25th September 2007, 10:36 AM	#6
DarkOne diyAudio Member Join Date: Oct 2001 Location: Bratislava	You should also move resistors from drain of output transistors to their source to improve linearity. __________________ Regards Robo

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25th September 2007, 08:20 AM	#3
Vix diyAudio Member Join Date: Nov 2003 Location: Somewhere on Planet Earth	And where is the nice paper, with all the explanations?

25th September 2007, 09:06 AM	#5
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Hi Carlos, yes, the DC offset depends on sameness of N and P halves. It is not that bad, though, even with change of temperature. In case you disconnect the load, the DC increases substantially. Also, for higher ohm load the DC increases. And gain increases with load, this is a current output amplifier. The DC servo injecting current into input node would be the cure, as Ipanema has mentioned Best, Pavel

25th September 2007, 10:42 AM	#7
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	No, unless you want the amplifier to blow. And distortion s HIGHER with resistors moved into sources!!

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