How to build the F5

[tinitus]

I haven't decided yet, as I have yet to determine where the safety earth will go. Probably on the baseplate somewhere, on a dedicated screw.

to have short wires, I guess it would be ok with chassis thermistor connected to chassis bottom, close to supply caps CT 'ground'

and safety earth connected to chassis, close to mains connector

 

[Bksabath]

Hi 47 nF class x1
In the left of the picture close as possible to the bridge


They stop same of the switching noise the bridge make tinitus is quite right they still work...

I am not in any way telling you what to do but maybe you should find out more about them



Any tought about the thermistors I belive they run at about 150 C

I by pass the one I got after a few seconds.

On the right soldered directly on the relay output tags.

 

[Zen Mod]

......

 

[Bksabath]

Hi Zen
Tanks for pointer I may be wrong then with the 47 nf

1000VA 20 / 24 AC ?

Be realy realy wonderfuly out of caracter if you could tell as what they do
or we will have to wait till tomorow morning for some one else to do.


+ what being wrong by overscaling may do?

Now I know I will not sleep at all for tonight.

For the ones that may not know Zen he is telling us a few things.

A) he is watching

B) he cares

C) he think that those caps are if not important at least worth to get a table ready made with the best values for the Job.

D) that he is so good that he is got this ready for as in a couple of minutes.

E to FF cubed a number of things that even me once seen the error of my ways and started to love the man fail to grasp.

So tanks Zen realy apreciated.

Al

 

[Zen Mod]

that table is strictly for caps across secondaries , not caps across each diode in bridge .

I'm too lazy to write anything else than - caps are there for some snubing of peaks going in all directions

edit : table is saved from some clever thread here on DiyA .
it is not mine ;

I'm too dumb

 

[Bksabath]

Tanks any way
I wish I was so dumb that I could remember where I seen the info
I also wish I was so dumb that I could find the info once I know where I put it
And most of all so dumb that once I got the 2 above I could make any sense of it and use it propperly instead of my usual sledge hammer aproach.

So I supose will have to wait till the morow so some one whos has read all the books and newer built aniting will corect (big red Biro again).

So question is.

As I spent a fortune in ways to kill off a considerable number of my brain cells I would apreciate to know why same times capacitors are placed right across the diode bridge?

What is the capacitance should be and how is calculated?
what does it do?

I know that they should be Snuber capacitors that came in safety class Y 1 and 2 or X1 and 2 (or at least the fortune spent I mentioned before Is making me believe so)

 

[Zen Mod]

those are issues which you can grasp in two ways -

1. solder what you have in drawer and enjoy

2. go read some dusty and less dusty papers and enjoy


any snubber is there to snub some nasty peaks
diodes are producing peaks while shutting off and on , generally

xformer isn't happy , audio circ isn't happy , especially taking in account behavior of wakoo inductances , hidden inside big electrolytic cans ;

so - cure is - place small and fast capacitances on some strategic places ..... imagine diode as tiny switch ; you are used to see caps across switches , placed to suppress sparks ; same thing

caps across secondary are there , as last frontier to prevent nasty harsh going back to xformer ( back - looking from rectifier side )

calculus is hard - it depends of many things - load , load variations , voltage , type pf xformer ( think inductance ) , type of bridges ....... and most important - ability of writer/calculus operating individual to take all things in account , understanding them in same time

your's truly isn't one of these ...... so - take that table as Bible ...... and think about Super Bowl , or some other proper manly thing ....

royal wedding , maybe ?

 

[Nelson Pass]

Unless 2 or 3 twists will actually make a difference. ?

Pretty small. The transformer is the elephant on the dance
floor. I routinely re-route wire and twisting and so on
when I have a noise issue, and it's always the transformer
itself. Usually solved by rotating or replacing the
transformer.

So don't worry about it.

 

[crazycody1993]

Usually solved by rotating or replacing the
transformer.

So don't worry about it.

Rotating?? how much rotation does it take to move an interfering magnetic wave away from 'circuit' its interfering with?? Is there a predetermined are of where the magnetic field is present? or is it just a spacing thats present, not exactly pin-pointable by looking at the transformer?

 

[Bksabath]

Tanks Zen.

Got loads of 47 nF X1 in the draw

Beter with than whitout I dumbly presume.

Tanks for the link to the snubbers

 

[AndrewT]

X1, X2, Y1 and Y2 are rated for connection across the mains.

Across the isolated secondaries one does not need X nor Y rated capacitors. It becomes an option depending on one's voltages and preferences.

 

[Bksabath]

Same more progress

Oky doky
Got same feet for the beast.

£7.50 for all 3 of them.

First go at the protection board

NTE7100 and Amplimo relay

And realised that I may need same more space.

 

[CanAm Man]

CL-6 temperatures?

Hi 47 nF class x1
Any tought about the thermistors I belive they run at about 150 C

All, do the CL-6 in-rush limiters run as hot as 150 C, in the F5? I've seen a lot of pics (including the First Watt F5) where the CL-6's are directly mounted to PCBs...... (seems they would be running a lot cooler than 150 C, to PCB mount them).

I'm needing some newbie advice, on this one..... Thanks.....

 

[Zen Mod]

naah ........

they're cool enough

but you don't want to touch them while power is on

 

[CanAm Man]

naah ........

they're cool enough

but you don't want to touch them while power is on

but, but....do they get hot enough, to cook kilbasa?

 

[Zen Mod]

nope

as Yanks use to say

"there is no substitute for ....... Zippo "

 

[CanAm Man]

Mounting the bridge rectifiers?

I've read comments about using thermal grease to mount the full-wave bridge rectifiers to the amp chassis/bottom plate.

Is it essential? optional? unncecssary?

Standing by, with my Arctic Silver, if you think I need to do so......

Thanks

 

[AndrewT]

A ClassA amp draws continuous high levels of current through the rectifier.
As a result a ClassA rectifier runs much hotter than a ClassAB rectifier.
Additional heat put into the bottom plate will increase the internal ambient temperature.

 

[6L6]

I did use thermal grease on mine -- it is easy to do, it can't possible hurt, but more importantly, the datasheet says to do so.

 

[CanAm Man]

6L6.....what a radical idea....! When all else fails, or there are questions--read the tech data....

My bad. Since I have the thermal grease, and spare time....consider them "heatsunked"....

Thanks for the phone call......