Was thinking it: we should be able to use old coins for silver heatsinks by sanding them down. About $4 of silver in a quarter, $1.50 in a dime. That’s not really that bad, if you can find someone to sell you one coin, or the coins you need.
Might wind up spending $5 for a quarter, not that bad. Also Silver halves have about $8 in silver, maybe $10 or less if you can find someone who sells bullion.
The 65-69 halves are 40% silver. Could maybe use dollar coins or the silver eagles for really big projects
The dimes are under the 19mm of the penny and might be good for a pocket rocket.
I would assume this isnt true, that they contain $4.50 in silver. And wiki says the quarter is coated in 75% copper and 25% nickel, on a pure copper core (toatal just over 90% copper, just 10% nickel). You need pre 1965 quarters, which are apparently 90% silver.
OK, Im going to assume many many pre 65 quarters have already met their fate.
I have checked my change my entire life (my grandfather owned a prolific coin & stamp business, one of the largest in the Midwest), I’m 26 now and to date I have only found 5 pre ’64 quarters and about a dozen dimes in my pocket change. Yes they’re pretty uncommon to find in circulation but they’re not at all rare, just go to any coin shop and buy some of the ones they have at scrap value, no reason to buy the special ones.
Is it really going to matter that much? Mainly if you don’t machine a pill out the emitter base is going to be silver, but without something of good heat conductivity to push the emitter heat to will it really matter? Pulling it from the emitter is one thing, but having someplace for that heat to go is something entirely different
Idk people seem to think the sink pad technology is pretty good.
Apparently Brass will work sometimes, aluminum better, copper better still, silver even better.
If you need a better heatsink than copper, here is something better. Plus the dimes are about 18mm in diameter, which is about the right size. Kind of the ultimate heatsink.
I wish I could find the thread that I was reading about heatsinks and the link therein showing the different values….
Along the lines of the cost of the material for mass production, brass, aluminum, and copper are the “best” heat conductivity to cost ratio…but copper and brass are the only two easily solderable
Copper and aluminium sinkpads are well used in these parts, Noctigons are a made product fitting the description and they come in a variety of specific purpose made sizes. There is also an alternative product named Sinkpad, which is also copper. There are aluminium variants too.
There are ‘pills’ these are then attached to, also made from copper or aluminium. A cheap source of silver would interest some of the modders Im sure, but I was doubting there being an untapped source circulating in US currency. I assumed if they had value, they would be officially pulled, added to collections at the new value, or defaced as scrap silver.
If a quarter is worth a dollar in silver, and they are available at face value ($0.25) then I can see a lucrative business idea. Although I assume defacing US currency is illegal too?
It doesnt matter all that much. The most critical point is where the LED contacts the PCB, so use a copper PCB and if the pill is made from aluminium, screw it down. If its made from brass or copper, solder it down. Solder instead of glue will make a bigger difference than the material. Thats why I really like to see more and more hosts come with brass pills. :)
90% silver alloy has significantly reduced thermal conductivity compared to pure silver(just like any metal alloy),and that number is lower than pure copper for sure.
Yes better eliminate the thermal paste and solder it down to brass or copper if you have a copper mcpcb. I see people put a lot of paste under the LED "to heatsink better". that is the worst thing you can do, a thick layer of thermal grease or glue. On top of that I see many using the poor thermal conductivity Fujik glue, rated at 0.88W/m.K
Sterling Silver (92.5% Ag, 7.5% Cu) has a Electrical conductivity (IACS) rating of 96% where pure copper is 100% and pure silver is 105%.
It is is not a thermal conductivity rating, but shows that silver alloyed with copper (only) loses those absolute proprieties and usually electrical conductivity goes hand in hand with thermal conductivity in alloys. http://www.substech.com/dokuwiki/doku.php?id=sterling_silver
A very very thin layer, as a way to fill the gaps in the uneveness of the materials, barely matters what the material is, something there to keep the insulative air out…NOT as a gasket!
It IS illegal to melt CURRENT u.s.a. coins, for their melt value. xample? illegal to melt the current use ZINC pennies, because the zinc sometims becomes 2 cents in value per cent piece…
money not CURRENT in circulation? (example, old copper pennies…) is not current anymore… it s properly referred to as BULLION. It MAY be worth somthing collecting wise? or it MAY b worth something for its metal content…
but if its not current circulation? its legal to do what you want with it.
silver dimes, and copper penies, are fair game to do what you want to with them.
now, that said?
i HAVE taken a handful of zinc pennies before, and melted them, and poured them into a mold to make something. The secret service did not come crashing down my door, LMAO… but, i would NOT make a “business model” around getting the half-price ZINC by melting zinc pennies, when th price of zinc spikes… good way to end up in the federal pen, lol…
although it is illegal to “deface” us currency? The ARE vending machines you put a PENNY into, and pay a fee… and turn a CRANK and it makes a CHARM for a bracelet out of it… ad ther is also companies that specialize in putting “photographd faces” onto “real” US paper money? and th money is still legal tender…
just remember… ANY coins no longer IN CIRCULATION? are simply bullion to do with as you see fit…
