Another MoFo

[pre65]

I can't progress much further with the prototype till I get a few more parts so to populate the PCB.

So, I got thinking about how I might "box it up" into something that would fit on my rack, and not look like an eyesore. I found a pile of BBP that had been cut and routed to form a box, can't remember what it might have been for, but I laid it on the table and test fitted all the hardware. Seems to fit without too much trouble, but what about the heatsink ?

Then I thought of the Musical Fidelity A1, with the griddle (sorry-heatsink) on top ? So I thought, why not ?

It would need some thought on making the bias setting pot accessible, and having test probes on the back panel, but it's a challenge.

Something like this.

[ed]

I'm thinking this might be a bit of a turning point....

we've got 3 active mofo threads on the go at the mo and a few more hibernating....must mean something stirring shirley....

come on Paul, you know you want to!

very pretty by the way Phil.......not sure it makes the most efficient use of those heat sinks but I'm sure it will work.

[Ray P]

You realise that the heatsink will be less efficient laid flat like that?

[pre65]

You realise that the heatsink will be less efficient laid flat like that?

Yes Ray (and Ed), but if the heatsink is a tad too big (which it might be) that may not be a bad thing.

I won't progress the "design" any further until the prototype has been fired up and I have some empirical data on heat sink temperature.

[Nick]

You realise that the heatsink will be less efficient laid flat like that?

Not sure they will be. If it was upright, then the air will have to travel the entire length of the fins gaining heat as it goes and reducing the delta T as it travels so reducing the extraction of energy as it gets nearer the top. As Phil has it, air can enter at both ends of the sink and only travel half the length.

[pre65]

If it was upright would the increased air temp at the top give a small amount of "chimney effect" and the small increase in air velocity might negate the reduction in energy extraction ?

[Nick]

If it was upright would the increased air temp at the top give a small amount of "chimney effect" and the small increase in air velocity might negate the reduction in energy extraction ?

Maybe, as I said I wasn't sure, but the same effect will happen between the fins in the direction you have it. I guess it matters where the device is if it was upright the best location may be towards the bottom, but exactly where I don't know.

[pre65]

I thought it might have been good to use that heatsink as one (long) side of the box, but with the fins as they are the heatsink would be even more inefficient.

Lets see how the first test goes, I might need smaller heatsinks.

I was thinking about access to the bias pot earlier, I suppose making it remote from the pcb would be easiest.

[Nick]

I suppose making it remote from the pcb would be easiest.

You just love making aerials

[pre65]

I suppose making it remote from the pcb would be easiest.

You just love making aerials

Shielded wires, honest Guv.

[Nick]

I suppose making it remote from the pcb would be easiest.

You just love making aerials

Shielded wires, honest Guv.

Ok, in that case you love making capacitors

[pre65]

OK. Thoughts needed. I could make up a bracket so a 6mm shaft 10 turn pot was close as possible to the pcb, and then use a long shaft to an outside edge of the box.

I hope you notice I am heeding your advice.

[Nick]

How often does it need adjusting?

[pre65]

How often does it need adjusting?

Hopefully, not often.

But, I may experiment with different bias settings, so the adjuster needs to be reasonably accessible (ie without taking things apart).

[Nick]

But the PCB will be on the heatsink, so all you will need to do is unscrew the heatsink from the mounting bracket to get at the pot. Hardly much of a hardship.