F5 power amplifier

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AndrewT

R.I.P.
Joined 2004
Re: Powering F5 fans

steveleen said:
The modules, after removal from their wall wart cases, are small and they will be easy to mount in a corner of the amp case, fed by the incoming line AC.
Click to expand...
are/were the wallworts double insulated.

Do not modify them unless you can ensure that any thing connected to them cannot be touched when the chassis is closed. And similarly nothing else should be able to come loose and touch the bared innards.
 
steveleen

steveleen

Member
Joined 2004
I need help in identifying whether my Nokia cell phone charger units (to be used to power the F5 fans) are switch mode or linear -- I just don't have the electronics background, and have exhausted a web search on this. They are the older, fatter ones, and I think they are linear, but not sure. Here are the main parts I've identified:

on the PCB are:
NEC 2501 opto coupler
S1NC60 N-channel MOSFET
SB9471 (can't identify what this is)
Z625 (can't identify what this is)
rising above the PCB are:
1 small transformer (FM 6722)
4 small electrolytic caps
2 resistors, one of which is a 1 watter

If they are linear, they should be fine, and I will use them.
If they are switch mode, then their use is doubtful.

Can anyone help on which type they are?

Thanks,
Steve
 
danieljw

danieljw

Member
Joined 2005
Paid Member
properly designed switched mode power supplies can be an excellent choice for size/weight/power saving... it is a pity that alot of switched mode power supplies are poorly designed using cheap parts and minimal filtering / shielding.

having said that there are plenty of linear supplies out there which are a junk too

the reason there are probably less "junk" linear power supplies is their design tends to be less complex.

like everything it is a trade off.....

my ten cents.

-Dan
 
Mooly

Mooly

Administrator
Joined 2007
Paid Member
For anyone that wonders here's a quick way to tell.

1. If it works with no adjustment over 110 to 240volts it's switch mode.

2. Bring an unterminated scope probe close to it, again if switchmode you will see all the HF hash.

I would imagine HF contamination by electromagnetic radiation is more of an issue than any contamination of the actual mains supply.
 
L

labjr

Member
Joined 2003
I haven't seen a linear supply for any consumer device in many years. So pretty much everything you find will be a switcher. And I don't imagine you'll find a properly designed one from a consumer product.

If you lived in USA you could go to Home Depot and buy a doorbell transformer.
 
jackinnj

jackinnj

Member
Joined 2002
tech-diy.com
Lateral MOSFET F5

I am going to try this out (again) during the weekend. I really didn't push the ball very far along when the design first showed up as the results with the IRF/Vishay and Fairchild devices was so good right out of the box.

I am going to guess that 2 (matched) taste better than one.

Getting back to fans for the moment. You do need some protection in case of fan failure if you aren't going to invest in more aluminum.
 
R-K Rønningstad

R-K Rønningstad

Member
Joined 2006
labjr said:
I haven't seen a linear supply for any consumer device in many years. So pretty much everything you find will be a switcher. And I don't imagine you'll find a properly designed one from a consumer product.

If you lived in USA you could go to Home Depot and buy a doorbell transformer.
Click to expand...


What voltages and currents are in question?
Do you have some secondary present on a transformer you could use that and e.g. a TO220 can LM317 set to your correct voltage. I mean, use one of the F5 rails and drop it to 5V or whatever it was with a LM317. Or 7805 for that. Or a NPN and a zener or something simple. Depends on the power this thing are using....
 
L

labjr

Member
Joined 2003
R-K Rønningstad said:



What voltages and currents are in question?
Do you have some secondary present on a transformer you could use that and e.g. a TO220 can LM317 set to your correct voltage. I mean, use one of the F5 rails and drop it to 5V or whatever it was with a LM317. Or 7805 for that. Or a NPN and a zener or something simple. Depends on the power this thing are using....
Click to expand...

I thought he wanted to isolate the fan circuit and any noise it generates from the audio power. The stock toroids don't have an extra secondary winding for this. Seems just as easy to use a small transformer for the purpose.
 
steveleen

steveleen

Member
Joined 2004
Just tested the F5 using the Nokia charger units to power the fans, with a switch attached to compare sound with and without. The magical see-through clarity of the F5 disappears when the charger units are engaged.
I will build a simple dedicated power supply for the fans, using a small transformer.
Thanks,
Steve
 
maxlorenz

maxlorenz

Member
Joined 2003
youtube.com/channel/UCIRNCQpvrl-EfalifsmR4KA
Altmann's SPLIF topology:

Uff! Another one that came late to the F5 party. I started reading the entire thread when you were at page 140 and look now we are on page 154! :mad:

Anyway, I came to know simultaneously the SPLIF feedback topology, the Selectronic Triphon amp and the F5 and obviously I went tempted to try the SPLIF on (both) amp(s):

http://www.altmann.haan.de/splif_page/

I think that maybe the Selectronic, with its lower bias (+/-260mA...) will be safer to try this. Apart that F5's feedback looks more complex and I don't have a clue about if SPLIF will work here...

The good thing is that the power supply can be used for both, just swapping amplifier modules :cool: to compare. The SPLIF can be selected with a switch to perform ABAB comparisons.
:cool:

What do the wise think?
Is there anybody who has tried this mod?
Regards,
M
 
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