Allright little update, it's been a while now, so here is a long post for who could be interested:
I had an issue with the Toroidal you've seen on previous pics, while all was working good, i lost a voltage after a while, without any load attached....
So after checking things i found out that the winding of the secondary voltage that i lost was broken, faulty toroidal, the first company took care of this, but meanwhile i got myself another one, but from a different company that does "Audio" type ones, custom from one to whatever, at a fairly nice price, i know you'll say "why bother with having another Toroidal?" Well because "a good Toroidal" can take a lot of problems away.....
except for the shipping for only one Toroidal was a little steep, but wanted one going with some specification i wanted, like stranded wires, wire disposition etc..... The spare Toroidal will anyway be used in the future....
Did one revision of the boards, i was not very happy with them, had one small mechanical prob, but redid them mainly because wanted to mod a couple of things on the circuit and i wanted to use some different kind of connectors, I had used KK type Molex connector on the first boards, and i decided to change and use some other type ones that are more sturdy when fitted and that would take a little bit more heat and that can handle up to 20AWG Wires, and so i choosed Micro Fit 3.0 for Secondary and DC connections and Vreg, and Mini Fit JR connector for the Mains board, all Molex brand types.
They are nice connectors a little more expensive than normal KK ones, and as always, if you hate crimping than this will not help you out, the Micro Fit 3.0 are tiny and they all have locking pins that won't be able to take the cable out without the special tool (14Euros) as opposed to KK one that are easy to pull ou with a simple screwdriver.
On the Micro Fit 3.0, for testing purpose i tried to pull them out breaking the locking pins, one time won't harm the socket much when i tested it, but better check twice for where to insert the cable, takes that away.
And i solder all wired to the crimping connectors, i usually always do that, that also help to pulled the wire out if done a mistake on these connectors, not leaving the crimping connector inside....
As for the Mini Fit Jr connectors, these are the same ones used in your PC, and i had their tools for extracting, but again if you're carefull in first place than don't need all this.
Heat and Load:
I had tried with the remaining voltages i had on the first proto and the final one on a load of 1.3A on each rails (so about 9-10 modules on full load), and after 8hrs of load, the thing was getting pretty hot, and heatsink pretty hot to touch also (about 55°C), but voltages were remaining ok...
The rectifers were hot ( about 75 to 80°C) and one reason why i wanted to change the KK connectors for connectors that would handle up to 105°C,
the secondary connector is right next to the rectifiers.
The heat path of the rectifiers is open and has no obstacles, caps or whatever, this helps the vertical dissipation of their heat, and the life of the Caps
that are next to them.....
So for the power rails, i decided to limit at 1.25 A, using UMZ 250 slow blow SMT fuses, that are mounted under the board with a window giving acces to them.
On real world situation and using this one as a Lunchbox PSU for 8 random modules, the heat is WAY less of course, but the PSU gives some headroom,
and i'm sure will handle 11 random modules as well....
Noise:
Well that's where i didn't succeed in a way :-\, well will maybe try some things to attenuate the best way, but i guess that may be a tough one, and one problem i was anyway going to face....
It's absolutly not a loud hum at all, as i don't hear much, but i do see a nice Peak on the 50Hz Range, and its harmonics at 155 / 250 and 350hz at about -90db FS for the 50Hz Peak on the plug-in i quickly used to visualise it, that on the 8th Module, the one as close to the PSU, didn't do fancy measuring for now, finished the module in the week-end.....
I'm not a pro in that domain but i guess lots of parameters could lead to this, and some modules will likely be more sensitive to stray electromagnetic fields than others, and that anyway the disadvantage of having a PSU close to modules or whatever electronic device....
Maybe my circuit boards design for home etch double sided PCB, and with the fact that top copper is not connected to each Parts on GND as on Thru Hole PCB's could be a prob as well, for testing purpose i did connect the top copper used for saving etching bath to PSU GND point on each boards but that didn't change much.....
Also maybe shield the Secondary wires as they are pretty close to the IEC Plug?
Toroidal is an "Audio" spec'd one, words taken from the manufacturer:
"the transformer is wound on high inductive, selected and measured core. Core and all the windings are impregnated. Transformer also has electric and electromagnetic shields, epoxy filled interior etc..."
Concerning the Toroidal, I did choose a disposition of wires, that doesn't give me the opportunity to turn this one enough to check its best position, maybe a bad move as well, but i wanted a clean short path to the PCB's.
I'm thinking of maybe trying to use some Mu Metal, fitting one layer around the Toroidal, this one has already been made with a Grain oriented sheet around it, but i have read that adding different materials of different permeability works good? Will see....
Or one plane sheet on the Transformer Bracket, but that would mean, drilling holes and cutting in the sheet in different ways, wich is not very nice for keeping the Mumetal properties as its best....
Or both, but that would take the price up......
I don't have an API Lunchbox PSU and dont know how it behaves in terms of Noise, but is there any stray electromagnetic fields problem with the module close to it?
All in all it was more a time killer project than an expensive one, all is hand made so....
Money was spend on electronic components and Transformers, these were the only expensive parts.....
Anyway let's cut the BS, here are some pictures of the process, and components used etc.. etc...
Milling the heatsink at my friends workshop:
Panasonic FK SMD Caps, gently bended pins for Thru hole
, maybe not a good idea, but the legs are flexible and it's possible to
thin the legs for reinforcing the bent area, works like a charm, and it was the only ones getting in that tight space + they seem to be better than FC ones.
UMZ 250 SMD Schurter Fuses, Slow Blow fitted under the brd
Mini Fit 3.0 connectors
The Angled Connectors have PCB locking, wich makes them stay still on board, KK angled ones seem too loose compared to them,
the only minus point is that it can be hard to pull the connector out, but that's better as a Lunchbox is made for taken out of the Studio and
may be confronted to tough situations...
Crimp connector fitting position
I crimp with some small needle plier, add a little solder, done, time killer but anyway....
The Vreg mounting and their wriring using 3 way Micro Fit 3.0 Connectors, wires are soldered on a PCB, to avoid having them
soldered directly on pins, as this is not a good idea when assembling and dismantling things, it will easily stress the Vreg pins and
break over time, but you still need to bend the lead fairly close to its case, but once....
Vreg PCB Asesembly, with PCB for the Front Led's using ribbon cable
Big Caps PCB assembly
Rectifier PCB
Toroidal Transformer
Mains and Toroidal Assembly + PCB
Load test, thanks to my buddy that gives me all the heatsinks his company is having fun throwing away, the Big resistors Heatsink is one of them as well as the PSU one.
LED before the Fuses for quick visual check, as the Ceramic fuses won't give any visual without a DMM.
Testing on some random modules (and some without knob ones haha), mainly for load, but also Audio
VOILA, now lets see what can be done for the Stray Electromagnetic fields, hmmmmmm
I had an issue with the Toroidal you've seen on previous pics, while all was working good, i lost a voltage after a while, without any load attached....
So after checking things i found out that the winding of the secondary voltage that i lost was broken, faulty toroidal, the first company took care of this, but meanwhile i got myself another one, but from a different company that does "Audio" type ones, custom from one to whatever, at a fairly nice price, i know you'll say "why bother with having another Toroidal?" Well because "a good Toroidal" can take a lot of problems away.....
except for the shipping for only one Toroidal was a little steep, but wanted one going with some specification i wanted, like stranded wires, wire disposition etc..... The spare Toroidal will anyway be used in the future....
Did one revision of the boards, i was not very happy with them, had one small mechanical prob, but redid them mainly because wanted to mod a couple of things on the circuit and i wanted to use some different kind of connectors, I had used KK type Molex connector on the first boards, and i decided to change and use some other type ones that are more sturdy when fitted and that would take a little bit more heat and that can handle up to 20AWG Wires, and so i choosed Micro Fit 3.0 for Secondary and DC connections and Vreg, and Mini Fit JR connector for the Mains board, all Molex brand types.
They are nice connectors a little more expensive than normal KK ones, and as always, if you hate crimping than this will not help you out, the Micro Fit 3.0 are tiny and they all have locking pins that won't be able to take the cable out without the special tool (14Euros) as opposed to KK one that are easy to pull ou with a simple screwdriver.
On the Micro Fit 3.0, for testing purpose i tried to pull them out breaking the locking pins, one time won't harm the socket much when i tested it, but better check twice for where to insert the cable, takes that away.
And i solder all wired to the crimping connectors, i usually always do that, that also help to pulled the wire out if done a mistake on these connectors, not leaving the crimping connector inside....
As for the Mini Fit Jr connectors, these are the same ones used in your PC, and i had their tools for extracting, but again if you're carefull in first place than don't need all this.
Heat and Load:
I had tried with the remaining voltages i had on the first proto and the final one on a load of 1.3A on each rails (so about 9-10 modules on full load), and after 8hrs of load, the thing was getting pretty hot, and heatsink pretty hot to touch also (about 55°C), but voltages were remaining ok...
The rectifers were hot ( about 75 to 80°C) and one reason why i wanted to change the KK connectors for connectors that would handle up to 105°C,
the secondary connector is right next to the rectifiers.
The heat path of the rectifiers is open and has no obstacles, caps or whatever, this helps the vertical dissipation of their heat, and the life of the Caps
that are next to them.....
So for the power rails, i decided to limit at 1.25 A, using UMZ 250 slow blow SMT fuses, that are mounted under the board with a window giving acces to them.
On real world situation and using this one as a Lunchbox PSU for 8 random modules, the heat is WAY less of course, but the PSU gives some headroom,
and i'm sure will handle 11 random modules as well....
Noise:
Well that's where i didn't succeed in a way :-\, well will maybe try some things to attenuate the best way, but i guess that may be a tough one, and one problem i was anyway going to face....
It's absolutly not a loud hum at all, as i don't hear much, but i do see a nice Peak on the 50Hz Range, and its harmonics at 155 / 250 and 350hz at about -90db FS for the 50Hz Peak on the plug-in i quickly used to visualise it, that on the 8th Module, the one as close to the PSU, didn't do fancy measuring for now, finished the module in the week-end.....
I'm not a pro in that domain but i guess lots of parameters could lead to this, and some modules will likely be more sensitive to stray electromagnetic fields than others, and that anyway the disadvantage of having a PSU close to modules or whatever electronic device....
Maybe my circuit boards design for home etch double sided PCB, and with the fact that top copper is not connected to each Parts on GND as on Thru Hole PCB's could be a prob as well, for testing purpose i did connect the top copper used for saving etching bath to PSU GND point on each boards but that didn't change much.....
Also maybe shield the Secondary wires as they are pretty close to the IEC Plug?
Toroidal is an "Audio" spec'd one, words taken from the manufacturer:
"the transformer is wound on high inductive, selected and measured core. Core and all the windings are impregnated. Transformer also has electric and electromagnetic shields, epoxy filled interior etc..."
Concerning the Toroidal, I did choose a disposition of wires, that doesn't give me the opportunity to turn this one enough to check its best position, maybe a bad move as well, but i wanted a clean short path to the PCB's.
I'm thinking of maybe trying to use some Mu Metal, fitting one layer around the Toroidal, this one has already been made with a Grain oriented sheet around it, but i have read that adding different materials of different permeability works good? Will see....
Or one plane sheet on the Transformer Bracket, but that would mean, drilling holes and cutting in the sheet in different ways, wich is not very nice for keeping the Mumetal properties as its best....
Or both, but that would take the price up......
I don't have an API Lunchbox PSU and dont know how it behaves in terms of Noise, but is there any stray electromagnetic fields problem with the module close to it?
All in all it was more a time killer project than an expensive one, all is hand made so....
Money was spend on electronic components and Transformers, these were the only expensive parts.....
Anyway let's cut the BS, here are some pictures of the process, and components used etc.. etc...
Milling the heatsink at my friends workshop:
Panasonic FK SMD Caps, gently bended pins for Thru hole
, maybe not a good idea, but the legs are flexible and it's possible tothin the legs for reinforcing the bent area, works like a charm, and it was the only ones getting in that tight space + they seem to be better than FC ones.
UMZ 250 SMD Schurter Fuses, Slow Blow fitted under the brd
Mini Fit 3.0 connectors
The Angled Connectors have PCB locking, wich makes them stay still on board, KK angled ones seem too loose compared to them,
the only minus point is that it can be hard to pull the connector out, but that's better as a Lunchbox is made for taken out of the Studio and
may be confronted to tough situations...
Crimp connector fitting position
I crimp with some small needle plier, add a little solder, done, time killer but anyway....
The Vreg mounting and their wriring using 3 way Micro Fit 3.0 Connectors, wires are soldered on a PCB, to avoid having them
soldered directly on pins, as this is not a good idea when assembling and dismantling things, it will easily stress the Vreg pins and
break over time, but you still need to bend the lead fairly close to its case, but once....
Vreg PCB Asesembly, with PCB for the Front Led's using ribbon cable
Big Caps PCB assembly
Rectifier PCB
Toroidal Transformer
Mains and Toroidal Assembly + PCB
Load test, thanks to my buddy that gives me all the heatsinks his company is having fun throwing away, the Big resistors Heatsink is one of them as well as the PSU one.
LED before the Fuses for quick visual check, as the Ceramic fuses won't give any visual without a DMM.
Testing on some random modules (and some without knob ones haha), mainly for load, but also Audio
VOILA, now lets see what can be done for the Stray Electromagnetic fields, hmmmmmm
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