flg said:
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 🙂
Attachments
Re: Lee with a capital L
Sure, thanks.
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...
Magura said:
Sure, thanks.
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...
Who knows what this thread is about... It's a split from another one?
Can a moderator do something about this?
Can a moderator do something about this?
It most likely is an inductor related issue, cause I have seen nothing of it. I use an air core inductor with a DCR of (as I recall) 2.4R.
With a 120mH inductor, you should not experience this sort of problem.
Magura 🙂
With a 120mH inductor, you should not experience this sort of problem.
Magura 🙂
apassgear said:
I started a new thread to not pollute the original thread, which is about a cascoded BOZ:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=108581
There is no connection between the two threads.
This thread is about an inductor loaded ZV9 style amp.
Magura 🙂
apassgear said:
apassgear, pardon us 😀 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???
SY said:
Magura, did you see this post?
Yep, Just did not have much good to say?... Had to go visit my mother...
I'm tryin some things now...
😀
flg said:
Yep, but didn't relly feel any big need for changing the title, so I decided to leave it up to those unhappy with the current title.
Those 10 members whom has any interest in this thread will find it no matter what the title is 😀
Magura 🙂
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???
So, might I assume that the inductance is not high enough???
It can't possibly be the problem, as I have only 80mH.
This may be a shot in the dark, but have you tried to run it with only 1 set of FET's instead of the two in parallel?
Magura 🙂
This may be a shot in the dark, but have you tried to run it with only 1 set of FET's instead of the two in parallel?
Magura 🙂
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
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
But could you just to exclude the possibility of such a problem, try and disconnect 1 pair?
As I wrote earlier, I have a hard time seing where your circuit differs basicly from mine, besides the two cascoded fets....and I had no such problem.
Magura 🙂
As I wrote earlier, I have a hard time seing where your circuit differs basicly from mine, besides the two cascoded fets....and I had no such problem.
Magura 🙂
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???
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???
- Status
- Not open for further replies.