6N7...this configuration work ?

[aldovan]

Friends

I want use the two sections of a 6N7 as voltage amplifier in cascade.
This configuration is possible ? Work without problem?


Thanks,

Aldovan

 

[Shoog]

No grid leak on either section. No it won't work as drawn.

Shoog

 

[aldovan]

Sorry I forget...

No grid leak on either section. No it won't work as drawn.

Shoog

OK, AND NOW ?

 

[ilimzn]

...And it is in danger of becoming a Schmitt trigger circuit. In this case the common cathode is actually positive feedback. Although the LED has a very low impedance compared to the cathodes, looking at it on a dB scale shows a problem - this amplifier will have a small hysteresis WRT input signal. I.e. it will be non-linear in a ost unwelcome fashion. If you are building a stereo amp, use one 6N7 as the first stage and another as the second stage, do not use one for both stages.

 

[aldovan]

Ok, and now ?

...And it is in danger of becoming a Schmitt trigger circuit. In this case the common cathode is actually positive feedback. Although the LED has a very low impedance compared to the cathodes, looking at it on a dB scale shows a problem - this amplifier will have a small hysteresis WRT input signal. I.e. it will be non-linear in a ost unwelcome fashion. If you are building a stereo amp, use one 6N7 as the first stage and another as the second stage, do not use one for both stages.

Ok, and now, work ?

 

[aldovan]

new variation

Ok, and now, work ?
View attachment 358343

And now ?

 

[Merlinb]

OK, AND NOW ?

View attachment 358342

Yes that will work. You don't need to worry about Schmitt trigger action with only an LED in the cathode circuit; it's impedance is negligible.

CCDA Noval Stereo PCB

 

[aldovan]

Yes that will work. You don't need to worry about Schmitt trigger action with only an LED in the cathode circuit; it's impedance is negligible.
CCDA Noval Stereo PCB

But I need the capacitor in parallel or not ?

 

[Merlinb]

But I need the capacitor in parallel or not ?

You don't *need* one, but you can try it if you like.

Also, I think you meant to use 47k anode resistors and not 4.7k.

 

[aldovan]

You don't *need* one, but you can try it if you like.

Also, I think you meant to use 47k anode resistors and not 4.7k.

No, I want driver a power triode.
Now the circuit is ok ?
I will use 600V in the plates and the catode current is 40mA,
The tube is replaced by RK34.

 

[aldovan]

New circuit with the RK34

Now I redesign the circuit.
The zener do not work, I will use a resistor.

 

[artosalo]

You have some 420 V at the anode and 15 W dissipation per triode.
6W is the absolute maximum limit by the manufacturer.

And now when you changed the LED to cathode resistor a by pass capacitor is required.

Can you describe what you plan to build ?

 

[Vinylsavor]

Hi!

As has been mentioned before: 4,7k is way to low as a plate load resistor for the 6N7. This would give big distortion and very little gain.

You should share more details what you intend to do then you can get better advice.
How much gain do you need?
Which tube do you intend to drive?

As much as I like the 6N7 I think you will be better of with another tube. I only use it with parallel sections. The individual sections have a plate resistance of over 20k and bias current of 3mA. That's ot much to drive anything

Best regards

Thomas