Zen -> Cen -> Sen, evolution of a minimalistic IV Converter

[samoloko]

thank you for reply but 4 x 9 VAC Is what I like to get and It Is not imited to R core

[RollE2k]

Originally Posted by samoloko

how about 4 x 9Vac
you can always do a 2 x 18Vac
If you can arrange It there will be much people Involved and price will be lower

Sorry, but that would make me need two transformers which wouldn't fit my case. And since i would need two transformers price would probably be cheaper - but not for me, since would need to more than half the price for it.

i'll be ordering custom r-core from vt4c :-)

[LuisMCP]

I have 4 x 9V NiMH batteries, and I get 2 x 18V when I put in series, and I can to fed each channel with 18V.

Batteries are of 9V 280 mAh and I build the Xen-Audio charger following the design criteria I saw in a Excel sheet.

Two batteries has an R of 22 ohm and a relay and a voltage regulator with 17,2V at Output for charging.

I have checked this connections and all seems OK, but allways get the batteries totally discharged in a day.

I will try rising the charging voltage ...

[EUVL]

> but allways get the batteries totally discharged in a day ....

I don't quite understand what you mean.
You leave the SEN on all day ? Or you cannot recharge within 24 hours ?

If you are using 2SK369V, your total consumption is about 40mA per SEN circuit (half the PCB).
So 280mAh will last 7 hours at most. So if you leave it on all day, surely it will be totally discharged.
NiMH does not like over-discharged.
And your batteries would probably be not in perfect shape by now if you would have repeatedly leave it on all day.
The charging circuit published is slow charge, meaning that you need ~20 hours till fully recharged.

Then those 9V NiMH batteries have a nominal voltage of 8.4V. When fully charged they would be 9.8V.
So according to the excel sheet, you should be using 20V voltage regulator followed by a 57R resistor when you have 2 of these in series.


Patrick

[LuisMCP]

Originally Posted by EUVL

> but allways get the batteries totally discharged in a day ....

I don't quite understand what you mean.
You leave the SEN on all day ? Or you cannot recharge within 24 hours ?

If you are using 2SK369V, your total consumption is about 40mA per SEN circuit (half the PCB).
So 280mAh will last 7 hours at most. So if you leave it on all day, surely it will be totally discharged.
NiMH does not like over-discharged.
And your batteries would probably be not in perfect shape by now if you would have repeatedly leave it on all day.
The charging circuit published is slow charge, meaning that you need ~20 hours till fully recharged.

Then those 9V NiMH batteries have a nominal voltage of 8.4V. When fully charged they would be 9.8V.
So according to the excel sheet, you should be using 20V voltage regulator followed by a 57R resistor when you have 2 of these in series.


Patrick

Ouch!

I put 12 cells (16,8V fully charged), 560 mAh (280+280) and get 17,2V.. !!!

I see that i was wrong

Well i will try with 20V and 57R

Thanks Pratrick !

[EUVL]

57R is for 2x 9V batteries wired in series to give 18V.
For 4 batteries, you need to use two separate 57R resistors.
Do not wire the two sets of batteries in parallel during charging.


Patrick

[EUVL]

Elsewhere the SEN IV has been accused of having poor or no PSRR.
PCM1704 NOS Strange Clipping

I wanted to find out for myself, so I did some quick simulation using my proven Spice models.
The input current was set to zero, and a 2V pk-pk noise voltage was added to the PSU.
The output is then plotted against frequency.

The first graph belongs to the SEN V18 for ES9018, using 2SK369Vs.
This is the worst of all variants, due to the higher capacitances of the 2SK369's.
Still, I personally would not consider -42dB at 100kHz to be poor PSRR.

The second graph belongs to the Cascoded SEN for PCM1704, using J111 cascoded BF862s.
I do not consider PSRR of -66dB at 1MHz to be any issue at all.

Most of your output noise will come from the digital noise of the DAC, not the IV PSU.
Unless of course you have really poor power supplies with huge ripples at HF.


Cheers,
Patrick

[smms73]

The problem with the cen and sen is the common noise rejection ratio that is zero .
The numbers that you present is the measure of the diferential noise rejection ratio.

One must have very careful in choose the power transformer , separate coils is a must .There are some exemples of common noise supression filters in the internet.

http://www.murata.com/products/emc/k...pdf/26to30.pdf

[bcarso]

Originally Posted by smms73

The problem with the cen and sen is the common noise rejection ratio that is zero .
The numbers that you present is the measure of the diferential noise rejection ratio.

One must have very careful in choose the power transformer , separate coils is a must .There are some exemples of common noise supression filters in the internet.

http://www.murata.com/products/emc/k...pdf/26to30.pdf

I know it's difficult to read everything in these long threads, but there have been extensive discussions of these issues, including schematics and specifications of common-mode chokes.

[smms73]

Indeed I have Missed a lot of the discussion , the thread is very long