The Wire LPUHP 16W Power Amp parts GB

[qusp]

Hey guys, just to update, We have been waiting for the Keratherm to arrive before finishing the packing, so I can go get the materials with final size and weight and work out the shipping costs. it was actually picked up on the 1st and vanished off the tracking radar on the 2nd and hasnt registered arrival in AU yet (5th your time is Saturday 6th here, so not sure if it was meant to be yesterday or today, but neither came to pass). it was sent GXG and they told me it would be here on the 5th, I was under the impression that GXG stood for Global eXpress Guaranteed, but it didnt arrive so ive sent an email to see if we can get the rebate/refund for the shipping.

Its annoying, as Hochopeper and I set time aside this weekend and its a long weekend, so it wont be here till Tuesday at the earliest now.

Whos going to volunteer for the US chapter to receive and bounce it onto individuals? do we want to do this? this way you can probably fairly cheaply band together for express shipping with tracking and have it in your hands sooner. since its not looking good for the sinks shipping will be cheaper of course. i'm going to email Mark one last time tonight with pics of my build to say 'dont you want this?' but I dont expect a response =( something has to have happened; he hasnt even logged into the forum for weeks.

so we can just use the stock sinks in the BOM, or you can buy a 8-10mm thick alloy or copper block sized the same as the sink and install this on the bottom as a heat spreader and to raise the unit so there is clearance for the parts and solder joints on the bottom, perhaps even put some plastic sheet to cover the rest of the area underneath in case of accident. this would probably even be enough by itself, but the idea is to use this as a way of using your chassis floor as a sink, so we would bolt through it, into the floor. there should not be any need for anything on top after this, but you may do as you wish.

now we could buy such a flat wide 'bar/sheet' from online metals cut to length and drill the holes ourselves. according to their quote it would be $75usd for 30 pieces of that size 1/4" thick T6-6061 alloy (so it doesnt corrode) or $270 for 30 pieces the same of C110 half hard ETP copper. thats before shipping, so someone in the US would have to send them out.

thoughts? better decide this stuff just in case as this format would mean I was cutting the keratherm to a different format

[hochopeper]

I think anything mounted on the under side of the pcb should be 2 bars rather than a single large block, U3 gets in the way and the center area is probably not as good for taking heat as there is no copper pour there on top or bottom pcb layer.

I guess something like 60mm (L) x 20mm (W) would hit the mark.

For simplicity of mounting it all level on the floor of the enclosure would it be worth getting 3 blocks per channel and placing one across underneath the transformer and use the 3 blocks instead of standoffs? If copper is chosen for the heatsinking blocks we could always just get alu for the one under transformer because copper is a bit excessive in that application!

[qusp]

yeah you right, I was just going to use the 2 bolts and the front standoff holes and pinch the bars between the board and the floor, because the opa JUST gets in the way, but yeah OK, that as you say doesnt really impact performance as theres no copper there anyway. not sure if it'll save any money on copper though, as there is a fee per cut that is a larger percentage of the T6 price than copper but all the same. hmm I suppose we could make it a pretty small piece of copper for the rear, because it would be nice to be consistent even if its overkill. so either all Cu or all T6 IMO i'm going to be doing this whether or not anyone else is interested, I figure you'll come along though Chris, anyone else?

just get a small thinner piece for the lme49990? could just stick a thinner piece there with thermal adhesive, if we cant find one that will exactly match to make it contact the floor

[hochopeper]

Yeah, mainly because it saves me worrying about enclosure ventilation too much, still haven't settled on an enclosure idea yet so not having to allow for that gives me a touch less to worry about.

[qusp]

so youre not getting U channel? pretty cheap enclosure and if it had tall enough 'walls' could bolt it to anything (like the wall of the large amp for example) as the roof with everything firmly attached to the floor.


ahh thats right you are getting enough to try a few variations. yeah thats part of my reasoning too, it makes thermal fairly independent of the final design

[wirewiggler]

If you want to ship to me and I can redistribute it in the US, though I will be gone the second half of May.

Bill

[qusp]

ok so when would we need to have this all to you to redistribute at the latest? i'll be finished working out my other orders there in the next 24-48hrs, apparently they ship normally within 24hrs.

so hands up guys, who would be keen on these little copper or alloy blocks cut to size and you just need to drill the holes and bolt down through the PCB, through this spreader and into/through your enclosure of choice, no heatsinking needed on top unless you want to? T6-6061 alloy solution probably about $9 for both channels delivered to Bill, C110 half-hard ETP copper about $20 for the 4 x (1 x 2.3") 0.187" thick pieces. thats based on getting enough for 30 channels, so 60 pieces. I made it 1" wide for simplicity, it'll protrude out the sides a couple mm, just enough to show the colour under your skirt =)

to be clear, both numbers cover us for 2 amps

[wirewiggler]

Sorry for slow reply,
I turns out I may not go kind of a plan B for work, if it does happen probably be gone less than a week,

Bill

[Ed LaFontaine]

It is time for me to move on the LME49600TS.

I would like to get to the 100 count price break @ $2.79 each.

LME49600TS/NOPB National Semiconductor (TI) Operational Amplifiers - Op Amps

Who would be interested?../..How many?

Also of interest:

http://www.mouser.com/ProductDetail/...%252b2psSUs%3d

Shipping arrangements at cost, from cheap, non-tracking (First Class) to Expedited, Tracking

[qusp]

typical, so we buy digikeys last stock pretty much, they restock at a lower price and mouser undercuts DK, so now Chris and I pay more than anyone for our kits and nearly double (on the AU site its still 3.79aud in 100 piece racks)what you guys will for the most expensive part in the list. aaarrgh =( noone heres fault, but i'm pretty f#$@#d off right now...... wow I had to edit and do my own censoring, the forum software totally left that haha

just finished packing the kits, only keratherm cutting to go, i'm sending an email out tonight regarding the alternate heatsinking as in my post above to get an idea of who would be keen so I can finalize the size I cut, finish that this week and get everything on the way.

I might grab 10 Ed, we'll see when you do it, pretty non-plussed indeed. thanks DK..... mouser were nearly 3x that when I last bought one there a month ago, 11AUD nearly I think

actually no, probably about even (still under, i'm not going to do the math to find out by how much so I can be pissed) because shipping was free as came straight here. there was bugger all price break for bulk for ours too. I wonder why, perhaps the new Ti based stock is cheaper because larger volumes were produced?