Cascaded gain stages in a circuit simulator

[peteb]

Not quite working yet.

I want to get two gain stages behaving identically and then connect them in series.

what can be done with this?


I am not sure.


I think one tube stage could cut one side of the signal and then the other tube stage could cut the other side of the signal.

two single ended stages in series could look like one push pull stage.

what ever. I don’t know.

 

[Phrygian77]

If you want each one to clip the opposite side of the signal, you can't build them identical. You need the second one warm biased for grid current clipping, and the preceding stage cold biased for cutoff clipping. You'll still want/need some attenuation between them to balance it out.

 

[YellowBoots]

If you want each one to clip the opposite side of the signal, you can't build them identical. You need the second one warm biased for grid current clipping, and the preceding stage cold biased for cutoff clipping. You'll still want/need some attenuation between them to balance it out.

Seems to me that if you want to clip the top and then the bottom, you will need two hot bias or two cold bias stages. If you follow hot with cold or cold with hot, you end up clipping the same side twice.

Good point about attenuation!

I will say it again—Falstad does not accurately model grid current and grid current limiting. It will show cut-off relatively well. I do not suggest serious large signal overdrive analysis using Falstad. You will learn the wrong thing if you assume it is correct. Use Falstad for small signal analysis.

 

[Phrygian77]

Seems to me that if you want to clip the top and then the bottom, you will need two hot bias or two cold bias stages. If you follow hot with cold or cold with hot, you end up clipping the same side twice.

You are correct. I was thinking about Blencowe's medium gain design, which clips asymmetrically first, and then more symmetrically as the gain is increased.

 

[peteb]

I am thinking plain Jane cutoff.

first the bottom, signal inversion, then the top.

 

[peteb]

I finally made my first goal that was harder than I thought.


This will be kind of fun to play around with.


3V x 41 = 123V

Two identical gain stages that are cascadable:

 

[peteb]

It works.

3400 gain, 60x56, clean signal out.

.030 V x 60 = 1.8 V.

1.8V x 56 = 101 V.

 

[peteb]

now it clips on both sides.

And it is starting to resemble the oscilloscope image of the champ.

Question: Why did the gain drop to 9 on stage 1?

0.200 V x 9 = 1.8 V.

1.8 V x 52 = 94 V.