Kristian's Aleph 2,3,4,5 series PCBs

[trigon]

And this is the main board. I may replace some Holco resistors with Cadocks later on. Only in signal path.

Trigon

[swede]

UrSv: If you have a look on the bottom side of your IRFP240 (which I for sure know you have at home), you'll see that there is little chance for connecting the screws to that metal piece on the "back side".

The insulating tubes are mainly for TO3.

Best,
//magnus

[UrSv]

Swede, yep.

My concern was mainly that the bars would be connected to the heatsink/chassis by the screw which means that any Drain that comes in contact with the mounting bar will be connected to the chassis. Any metal flake or other thing could do that.

You know I am picky...you should see my "finfilters".

/UrSv

[AMPMAN]

where did you get those heatsinks

[Peter Daniel]

You can forget about using plastic screws to connect the bars to the sinks. Those plastic screws are not strong enough (M3 or M4 are definitely a no-no ), unles you go for a larger size or use some other, stronger material. It would be even better if the bar was done out of copper. I've seen large insulating sheets in Digi-Key catalog, but they were quite expensive.

Why don't you just mount your FETs directly to the heatsiks and forget about all that troube?

Looks like Caddock MK 132 resistors would be perfect for using with that board. I don't like resistors placed vertically for no apparent reason.

Ampman, the heat sinks come from Mississauga, from R-Theta.

[kristijan-k]

Hello trigon,

I agree with Peter, the plastic screws would not be very good.

You can find silicone isolators in sheets 300 x 300 mm
(11,8 x 11,8 in) at http://www.rs-components.com ,
stock no. 403-279.

Your enclosed alu-profile would work ok.

You must note that some, not all, heatsinks are not perfectly
strait on the base, especially if they are very wide, so it would be a better idea to use silicone rubber isolators, instead mica types,
when you want to joint two longer sides with larger surface area.
With silicone rubber there will be less possibility for the gaps,
than with mica type, and the whole thing would be little more
efficient.

Also, for even better heat transfer, the Cu profile, instead Al,
would be even more efficient.

Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip

[trigon]

Hi.

Peter, would you happen to have any idea for the following problem:

My drill press is not reaching a distance needed for my alu-bars,
so that they can be installed on the center of my heatsinks, it is close
but not sure if it is ok?

I have not talked about plastic M3 or M4 screws that I wonted to use, instead
I was talking about M4 plastic bushes (iso-tips), but it looks to me that UrSv is right, it is to
dangerous to have those bars under the voltage.
But I still think that using three screws instead of six is advantage of using those bars.

Only problem that I am facing now is explained above and by the picture itself.
Not sure if using a Hand Drill I can achieve the good results of drilling three centre holles for those
bars. Got this drill press a 2-3 weeks ago from Canadian tire for $64.00 Canadian.

P.S. Peter I have placed resistors vertically because of the PCB layout where H4 can't fit
so not much choice, but as mentioned before, maybe later I will replaced them with Cadocks.

Thanks for any tip in advance

Trigon

[Peter Daniel]

I don't know if you noticed, but there is only one hole to be drilled by hand: the one in a center. To do it straight, you might make yourself a drill guide, like I show it here: http://www.diyvideo.com/forums/showt...5&pagenumber=8

[trigon]

Thanks


Trigon.