nouvelle electronique

[arex]

Hello everybody!

I found this diagram in the last issue of "Nouvelle Electronique". It is a simple class a amplifier, 10 watt output power, 10Hz to 100KHz. All resistors are 1/4watt. Nothing to tweak.

I am not sure on the wrightness of the diagram: R5=R6=18K???.
C2=220uF but C1 1000uF????. can anybody tell me, is this correct???.

Can I use a double power supply +- 12V by conecting C3 at 0 volt???.

And in general it is a useable/good diagram?

Thanks !

[Nelson Pass]

Looks a bit like the JLH with a constant current source
on top.

[arex]

I made a mistake: T1 is a pnp transistor.
The correct schematics joined:

[Tube_Dude]

Originally posted by arex


I am not sure on the wrightness of the diagram: R5=R6=18K???.

Yes...correct! Is for the middle point at the output , to be at half the supply voltage.

C2=220uF but C1 1000uF????. can anybody tell me, is this correct???.

C2 must be at least 2.200 uF for good low frequency response , with a 8 Ohm load.

[Tube_Dude]

I made a mistake: T1 is a pnp transistor.

T1 in your second schematic must be connected with emitter to C3 and T3 must be a PNP transistor.

[darkfenriz]

Originally posted by arex
I made a mistake: T1 is a pnp transistor.
The correct schematics joined:

No, no, no
T1 was OK, T3 wasn't

cheers

edit: Jorge was first, ignore

[arex]

WRONG again! T3 is a pnp too.
Excusez moi svp. THIS IS THE WRIGHT DRAWING.

Can I use a dual power supply by conecting C3 on 0 volt and eliminating C2??

Comparing with the JLH amp: the resistor on the Q2 colector (JLH) in a 7watt one.

Here (nouvelle electronique) the same resistor in the T4 emiter is a 1W ( 0.25 x 4). Why?

Thanks

[Tube_Dude]

Originally posted by arex


Can I use a dual power supply by conecting C3 on 0 volt and eliminating C2??

No , because that way , the offset will not be controlled...

Here (nouvelle electronique) the same resistor in the T4 emiter is a 1W ( 0.25 x 4). Why

Because in your schematic the dissipation in that resistor is ~ 0,6W..so 1W is enough .

Attention in your last schematic T1 is still up side down

[moamps]

And something is wrong with amp's grounding.(-Ve and C3 on same potential?)
Also, quiescent current is too small to reach 10W/8ohm.

Regards,
Milan

[arex]

No , because that way , the offset will not be controlled...

I will join another diagram, hope the wrigt.

Please excuse my ignorance, how must I modify the schematic to eliminate C1 ??