JAY X

Re: Bandwidth problem
« Reply #40 on: January 11, 2019, 06:01:13 PM »
Hi!

I wrote mhz, but i would say MHz,...megahertz.
That is the problem writing on a mobile phone... sorry!!

Jay x


abbey road d enfer

Re: Bandwidth problem
« Reply #41 on: January 12, 2019, 01:23:57 AM »
Hi!

I wrote mhz, but i would say MHz,...megahertz.
That is the problem writing on a mobile phone... sorry!!

Jay x
That's interference from all the crap from switchers, cellphones, WiFi... whatever. Just discount it.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
"The important thing is not to convince, but to give pause for thought." (B. Werber)
Star ground is for electricians.

JAY X

Re: Bandwidth problem
« Reply #42 on: January 12, 2019, 09:48:00 AM »
Hi,

Below  is a link for the pdf with ripple and noise measurements. The attachements does not work...

I said MHZ, but really was khz....sorry...my fault!  I think i confused the bandwidth of the picoscope, with the measurement. ::)

Jay x


download link:

https://mikrosum.webnode.es/_files/200000019-4a1984b0fa/VOLTAGE%20DOUBLER%20PSU%20RIPPLE%20V4.pdf

abbey road d enfer

Re: Bandwidth problem
« Reply #43 on: January 12, 2019, 05:08:56 PM »
Hi,

Below  is a link for the pdf with ripple and noise measurements. The attachements does not work...

I said MHZ, but really was khz....sorry...my fault!  I think i confused the bandwidth of the picoscope, with the measurement. ::)

Jay x


download link:

https://mikrosum.webnode.es/_files/200000019-4a1984b0fa/VOLTAGE%20DOUBLER%20PSU%20RIPPLE%20V4.pdf
All I can see is some signal in the MHz range, almost certainly picked up by the test cords. Not hum nor ripple.
The horizontal scale in the 1st graph is in us (microseconds); in order to catch hum, it should be in ms (milliseconds).
Who's right or wrong is irrelevant. What matters is what's right or wrong.
"The important thing is not to convince, but to give pause for thought." (B. Werber)
Star ground is for electricians.

JAY X

Re: Bandwidth problem
« Reply #44 on: January 13, 2019, 05:28:18 AM »
Hi,

Here are some measurements i did with another CRC filter: 470uf/22R/470uf. These measurements are in ms.

I really thought that my problem with the frequency response at both low and high end were due to the noise of psu...but perhaps the cause is other...

Jay x

https://mikrosum.webnode.es/_files/200000020-6e38c6f325/VOLTAGE%20DOUBLER%20PSU%20RIPPLE%20%20IN%20MS.pdf
« Last Edit: January 13, 2019, 05:32:21 AM by JAY X »

abbey road d enfer

Re: Bandwidth problem
« Reply #45 on: January 13, 2019, 05:55:23 AM »
Here are some measurements i did with another CRC filter: 470uf/22R/470uf. These measurements are in ms.
All these measurements are meaningless to me. I don't even know what you're measuring; is it the supply rail noise or the device's output noise. Anyway the waveforms do not look like hum/ripple.

Quote
I really thought that my problem with the frequency response at both low and high end were due to the noise of psu...but perhaps the cause is other...
There is no way ripple on the supply rail can result in BW limitations; look elsewhere.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
"The important thing is not to convince, but to give pause for thought." (B. Werber)
Star ground is for electricians.

JAY X

Re: Bandwidth problem
« Reply #46 on: January 13, 2019, 07:09:03 AM »
Hi Abbey!

The measurements are made at +V supply rail.

In any case, It is becoming clear that i have to investigate more to find out the causes.

Jay x

JAY X

Re: Bandwidth problem
« Reply #47 on: January 13, 2019, 11:47:38 AM »
Hi,

This is getting....weird :

I performed two audio tests, to see if the frequency response has changed or not.

The first fact is that, in my design, the PSU ripple filter affects the frequency response.
Why?...no clue..by now.

In the first test with CRC filter 1000uf/22R/1000uf, i got a notch in the frequency response, at 200hz -29,96dbu.

With the second CRC filter 470uf/22R/470uf i got a somewhat flatter response between 80 - 570hz,  and from there, the frequency response climbs 16dbu up to 20khz.

In both cases, this is not normal.
A PSU filter should not affect the frequency response of an audio  equipment.

So, there should be something wrong in my layout.

Maybe the Single point Ground?
Maybe...what?

Jay x
« Last Edit: January 13, 2019, 11:50:58 AM by JAY X »

JAY X

Re: Bandwidth problem
« Reply #48 on: Today at 06:58:55 AM »
Hi!

I'm going to give up with the voltage doubler psu. I will try a DC-DC converter from murata, and/or maybe a dc rail splitter circuit...
I will post schematics in the next coming weeks.

Jay x

 

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