Hi!
The situation is: now I have more or less everything I need for my Aleph5:
- all electronic parts;
- PCB design (made by kirc)
- trannie (4x25V and 900VA)
- power capacitors (4 x Sprague Powerlytic 36D: 69.000uF/50V each)
- 4 x heatsink: 300mm x 145mm x 40mm (Fisher one - same stuff as used in my Zen v4; just 5 cm longer)
So - the idea for chassis was to use one heatsink/side - so it would look very similar to original Aleph design - with internal measures 300 x 300 x 145 (and outside 380 x 380 x 155)
BUT! - capacitors are so big - that there is no way to combine them and transformer inside that place - well - it's possible - but then capacitors are almost touching heatsinks (that means they are around 1cm away from them - and that exactely almost beside MosFet - and that's the hotest place I guess) - and I guess that's not OK for them! What do you think??
So - posible solutions:
1) use of some extra corner Al plates (around 6 cm width) - so the chassis would change from "4 corner" to "8 corner" one ...
2) to add extra cca 12cm height to the chassis - simple - with using so thick Al plate as the "meat" of the heatsink is and just add it (but then upper floor would be wider because of the fins) - to put transformer in it and obove it capacitors - and above that PCB ...
3) separate chassis for PSU ...
Hmm - my thoughts about each of them:
1) The first one seems OK to me - and I think also the design could be quite interesting. But suddenly costs can rise a lot - because base and cover plate are suddenly 400 x 400 .. And also with internal WxD 460mm x 460mm that's quite big amp ...
2) The second - hmm - I guess it could look a bit odd - because the top would be 3cm wider on each side. And also the height would be at least 250mm - maybe even 300mm ...
- of course: It would be great looking if made in Aleph0 manner - but I'm not sure - in that way the air circulation could be a bit problematic ...
3) Separate PSU seems OK - it's not possible to get hum because of induction in loops; the temperature of chassis is normal - so it would also be better environment for capacitors; I guess it easier to have 2 smaller boxes than one that is huge from W x D or H point of view ...
OK, it would be a bit more expensive to build as 2nd solution; and somewhere equal to 1st.
Now I wonder - what are PROs and CONs for separated PSU?!?!
Are there any bad points??
And - how "bad" is to have capacitors in warm environment?? If the chassis itself is on cca 55°C - I guess the interior can get pretty warm too - at least 40°C ... And if they are located very near MosFets ...
Thanks for help!
OK
Stabist
The situation is: now I have more or less everything I need for my Aleph5:
- all electronic parts;
- PCB design (made by kirc)
- trannie (4x25V and 900VA)
- power capacitors (4 x Sprague Powerlytic 36D: 69.000uF/50V each)
- 4 x heatsink: 300mm x 145mm x 40mm (Fisher one - same stuff as used in my Zen v4; just 5 cm longer)
So - the idea for chassis was to use one heatsink/side - so it would look very similar to original Aleph design - with internal measures 300 x 300 x 145 (and outside 380 x 380 x 155)
BUT! - capacitors are so big - that there is no way to combine them and transformer inside that place - well - it's possible - but then capacitors are almost touching heatsinks (that means they are around 1cm away from them - and that exactely almost beside MosFet - and that's the hotest place I guess) - and I guess that's not OK for them! What do you think??
So - posible solutions:
1) use of some extra corner Al plates (around 6 cm width) - so the chassis would change from "4 corner" to "8 corner" one ...
2) to add extra cca 12cm height to the chassis - simple - with using so thick Al plate as the "meat" of the heatsink is and just add it (but then upper floor would be wider because of the fins) - to put transformer in it and obove it capacitors - and above that PCB ...
3) separate chassis for PSU ...
Hmm - my thoughts about each of them:
1) The first one seems OK to me - and I think also the design could be quite interesting. But suddenly costs can rise a lot - because base and cover plate are suddenly 400 x 400 .. And also with internal WxD 460mm x 460mm that's quite big amp ...
2) The second - hmm - I guess it could look a bit odd - because the top would be 3cm wider on each side. And also the height would be at least 250mm - maybe even 300mm ...
- of course: It would be great looking if made in Aleph0 manner - but I'm not sure - in that way the air circulation could be a bit problematic ...
3) Separate PSU seems OK - it's not possible to get hum because of induction in loops; the temperature of chassis is normal - so it would also be better environment for capacitors; I guess it easier to have 2 smaller boxes than one that is huge from W x D or H point of view ...
OK, it would be a bit more expensive to build as 2nd solution; and somewhere equal to 1st.
Now I wonder - what are PROs and CONs for separated PSU?!?!
Are there any bad points??
And - how "bad" is to have capacitors in warm environment?? If the chassis itself is on cca 55°C - I guess the interior can get pretty warm too - at least 40°C ... And if they are located very near MosFets ...
Thanks for help!
OK
Stabist
🙁
I feel a bit disapointed ... If such discussion was allready done - can atleast someone send me a link - I've done some "search" - but nothing came up that I could "use" ...
Can you please tell me at least what to consider when building up separate PSU?? I guess that we'll be my final solution - so I need some "tips & tricks" - is there something I must extra include or left out because of separate PSU??
Thanks again allready in advance!
I feel a bit disapointed ... If such discussion was allready done - can atleast someone send me a link - I've done some "search" - but nothing came up that I could "use" ...
Can you please tell me at least what to consider when building up separate PSU?? I guess that we'll be my final solution - so I need some "tips & tricks" - is there something I must extra include or left out because of separate PSU??
Thanks again allready in advance!
I was shortly going to place the same questions for an Aleph 2 so I hope someone gives you a reply. It would be useful to know what temperature caps you are using. I need to know what items to keep apart to avoid stray inteference & I expect you may need to know same. Perhaps if you don't get an answer it's because only Mr.Pass knows.
Stabist,
since your heatsinks will be around 50 to 60°C I would put the caps at 1 cm distance and leave it that way. This is about 20° under there max. working temperature for the specified lifespan so I wouldn´t bother.
In my opinion this will give you the nicest design.
william
since your heatsinks will be around 50 to 60°C I would put the caps at 1 cm distance and leave it that way. This is about 20° under there max. working temperature for the specified lifespan so I wouldn´t bother.
In my opinion this will give you the nicest design.
william
How about something like this? The black area is the heatsink and the red is a thick aluminum bar with angled corners. I doubt that you will find something exactly like the ones I tried to draw, but something similar would do to. Perhaps a square tube? Or you could make something yourselves. I once thought about doing this myself, but never got around to it.
Attachments
Kermit - something like that was one of my ideas ... Except - that corners would be a bit thinner ... But - now when I see your drawing - hmm - it's worth of invest some extra money - cause it could look stunning 😀
Thanks
So - you guys think there is no problem about temp - that's very good 🙂
The only thing is - yes - the heatsinks will here around 55-60°C - but trazsistor case will be at least at around 75-80°C - and capacitor will be very very close to it - that's the reason I'm concerned a bit ...
Thanks
So - you guys think there is no problem about temp - that's very good 🙂
The only thing is - yes - the heatsinks will here around 55-60°C - but trazsistor case will be at least at around 75-80°C - and capacitor will be very very close to it - that's the reason I'm concerned a bit ...
Stabist
Can you post dimensions of tranny, caps & pcb's to give us an idea of the scale of the problem
Can you post dimensions of tranny, caps & pcb's to give us an idea of the scale of the problem
Sure - tranny has fi=155mm and height 70mm
Each capacitor has fi=78mm and 132mm height (and there are four of them
The central pcb has 160x160
And then there will be aditional 4 pcbs: for each heatsink one - with 3 transistors each. But they are not made yet ...
And then - there are four heatsinks - 300 x 40 x 145
Any ideas very welcomed ...
If I'll find some extra time today - I'll go to friend and scan some drawings with some ideas I've allready made ...
Each capacitor has fi=78mm and 132mm height (and there are four of them
The central pcb has 160x160
And then there will be aditional 4 pcbs: for each heatsink one - with 3 transistors each. But they are not made yet ...
And then - there are four heatsinks - 300 x 40 x 145
Any ideas very welcomed ...
If I'll find some extra time today - I'll go to friend and scan some drawings with some ideas I've allready made ...
If you layout a 300mm square (actual size) position tranny at exact centre then the 4 big caps can stand upright (one on each corner)
They will clear heatsink by 20mm even allowing a shielding ally box around tranny.
The main pcb can then be positioned directly above & on tranny box but rotated by 45degrees. It then clears caps with room to spare.
You should also now see plenty of room for (3 mosfet) output pcb's & a very easy route for power in & power out.
You need to get more experienced opinion on the electrical effects of putting the caps on the four corners but if this is O.K.
your problem should be solved.
If this takes a bit of following let me know & I will scan & post a scale sketch/drawing.
They will clear heatsink by 20mm even allowing a shielding ally box around tranny.
The main pcb can then be positioned directly above & on tranny box but rotated by 45degrees. It then clears caps with room to spare.
You should also now see plenty of room for (3 mosfet) output pcb's & a very easy route for power in & power out.
You need to get more experienced opinion on the electrical effects of putting the caps on the four corners but if this is O.K.
your problem should be solved.
If this takes a bit of following let me know & I will scan & post a scale sketch/drawing.
Tim - thanks for possible solution - if telling the truth: that was my first option - the one I scare most - 'cause after transistors are mounted to heatsink - there is only 1cm left between capacitor and transistor ...
I have another solution - to add few cm in height (lets say 55mm - to get total height 200mm) - and then the trannie can be mountid in vertical position and with adding all four capacitors - what comes out is a PSU in the size of aprox. 240mm x 170mm x 160mm - and the PCB is mounted on the top ..
And closets point between capacitors and transistors is cca 2,5-3cm ...
I have another solution - to add few cm in height (lets say 55mm - to get total height 200mm) - and then the trannie can be mountid in vertical position and with adding all four capacitors - what comes out is a PSU in the size of aprox. 240mm x 170mm x 160mm - and the PCB is mounted on the top ..
And closets point between capacitors and transistors is cca 2,5-3cm ...
If you're worried about heating the caps with the fets, put a peice of adhesive backed foam on the part of the cap near the fet.
The cap generates very little heat and can dissapate through the other uncovered part, and be insulated from the heater.
I think the heat can easily migrate away from the insulated area and may be a solution to keep the smaller chassis.
The cap generates very little heat and can dissapate through the other uncovered part, and be insulated from the heater.
I think the heat can easily migrate away from the insulated area and may be a solution to keep the smaller chassis.
One suggestion is the 1/8" neoprene foam with presure sensitive adhisive like hardware stores sell as weatherstipping, or some car audio installers use as sound deadening in door panels etc.
Even a fish paper sheild between the caps anf fets would stop most of the radiant heat. (I think that's what they call that cardboard crap they put in electronic gear where the metal case is too close to the board to prevent shorts.) With a 85 deg rating on the caps, I don't think it would take much to protect the caps.
Even a fish paper sheild between the caps anf fets would stop most of the radiant heat. (I think that's what they call that cardboard crap they put in electronic gear where the metal case is too close to the board to prevent shorts.) With a 85 deg rating on the caps, I don't think it would take much to protect the caps.
An externally hosted image should be here but it was not working when we last tested it.
PTFE foam. Operating temperature -196°C to +260°C.
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