Inductor Loading Adventures

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Magura

Magura

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Joined 2003
class-a-labs.com
flg said:



Hmmm. Well, Ive had it running with the sig gen and the scope mostly with unmatched parts. I've listened to it on some cheapy spk'rs a little. but it had to low of an output cap for descent low freqs. Let me show you a pic of what it's set-up like for todays playing around...
The 120mH is a Hammond 195T5 5A 100mH Choke (measures 120mH @ 3.5A)
I'm going to look at the Open Loop Gain and Freq Response today and then add the R1 & R2 and see what I can get for Closed Loop response and gain...
Click to expand...


I thought this better get a life of it's own :)

This looks a lot like what I've been playing around with lately, though I've found it to be ok with massive heatsinking and just one cascode, as opposed to the two you have i parallel.

I used a 4.700uF E-cap and a 50uF film cap at the output. A 80mH inductor, and 40V rails.

I got a flat response curve down to 20Hz, below 20Hz it starts rolling off, but nothing worth mentioning.

Magura :)
 

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flg

flg

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Joined 2005
Re: Lee with a capital L

Magura said:



I thought this better get a life of it's own :)

Magura :)
Click to expand...


Sure, thanks. :smash: The low Freq problem I was speaking about is not really rolling off though. I start to see rolloff @ 30Hz and it's -3db about 6Hz(with Sine Waves). It's a "tilt" appearance to the squarewave @ low freq??? I was thinking it was to small an output cap??? You can begin to see saturation looking curvature to the squarewave at about 50Hz. But, this "tilt" bis gradually gets worse starting at maybe 1kHz??? By the time you get down to 10Hz, it's pretty much a sawtooth looking wave! I'm begining to think it's an inductor related phenomina??? I don't see it at the source resistors, only at the output...
 
flg

flg

Member
Joined 2005
apassgear said:
Who knows what this thread is about... It's a split from another one?

Can a moderator do something about this?
Click to expand...


apassgear, pardon us :D It's about a variation on the ZV8/ZV9 theme as can be seen in the 1st post. Basically substituting light bulbs or aleph CS with inductors.
I suppose a Mod could if they wanted to???
 
flg

flg

Member
Joined 2005
I have 2 of these 5A Chokes. So, I decided to hook them is series and paralell to see the effects. Paralell seemed to increase the square wave "tilt" by a noticeable amount. Series appeared to be only slightly better (less "tilt").
So, might I assume that the inductance is not high enough???
 
flg

flg

Member
Joined 2005
Yes, my first incarnation of this idea used 1 JFET. I was basically disappointed with a gain of about 8. I'm getting a voltage gain of about 15 now.
I have also previously tried several large transformer primaries, both toriod and EI core units. As I remember it, they all had this problem. They also all had more serious saturation looking curves visible with square wave testing. The EI's seemed better than the toriods. That is why I'm now trying a choke designed for real DC current operation...
N.P. has touched on these ideas somewhat in the ZV7 paper. I wanted to work out a single ended version :smash:
 
flg

flg

Member
Joined 2005
O.K. 1 LU device, 1 IR device cascoding it. 1.7A, 3.65V on the jfet, 27.7V at the Drain of the mosfet, 29V V+.
No real change in the low freq square wave. There is however something strange though. Open loop bandwidth seems much higher. Goes up to 200k before it starts to get a little distorted? Maybe my 50 ohm sig gen can drive 1 jfet better???
 
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