GRollins said:
They didn't, but epoxy resin systems have continued to evolve and the current ones adhere much better to metal.
There are even dedicated metal bonding epoxy resin types nowadays.
The composite resin panel (70% wood chips, 30% resin) is a very popular exterior material in the building construction industry overhere.
I've been using that stuff as outer layer material to make sandwich panels with an alloy core.
Easy to work with, a carbite tip saw blade cuts it as sharp as a razor blade, glueing the edges with epoxy resin transforms the panels into a unibody.
The beauty of the stuff is that the panels are smooth and already painted with a polyurethane system.
A soft grind and another 2-component paint layer gives it a professional look.
Interesting for DIY types is that a lot of residue of the material comes out of the building industry, it doesn't burn as easy as wood and it's easy to repair with resin.
The sandwich technique makes a 1/2" panel far more rigid than a 0.4" aluminum plate.
I bought hundreds of 4'x1' panels for less than $2/pc from a carpenter who resizes a lot of 8'x4' panels every 3 months, wider sized leftovers cost little more.
The nature of the stuff does require more vent holes though.
jacco vermeulen said:
The aluminium version is trademarked Devcon. Great for fixing holes and cracks in intake manifolds and filling unwanted holes in chassis panels.
GRollins said:
Try Emerson-Cuming's Stycast 2651. It's a two-part epoxy that we use in the aerospace industry. Bonds very well to metals.
www.emersoncuming.com
Best, Chuck Hansen
Grey, it is the lack of THERMAL CONDUCTIVITY that is the PROBLEM! I think we are confusing others with our jokes that go too far. People will start to take you seriously, and make enclosures that cannot remove the normal heat generated by the circuit itself, and it will cause big problems, maybe even fires. Yes, thermal exhausts or vents help, but even fan loading will not be enough for a serious class A-B power amp. I have such a 'failure' in my warehouse, made in 1981. Fast and powerful it was, but it destroyed output devices on a regular basis due to overheating. I used mini wood loudspeaker cabinets with airblown heatsinks that were fan pressurized. Without the secondary heat conduction that would normally be possible through a metal case, the components continually were at a temperature higher than usual. No more wood cabinets for me, but the front panel can usually be made of anything: Glass, plastic, metal, rock, epoxy, a fishtank (if the fish can take the increased temperature), etc.
Sorry to add on to this rant, but:
There is silver epoxy as well. It has excellent adhesion to metals, thermal conductivity, and heat resistance. I've used it before to bond semiconductor metal tabs to solid copper heat sinks, and the device was destroyed before i was able to remove it's metal tab form the copper. (I had to oxy-acetylene torch it to remove it) I didn't really want to have those two bonded in the first place (or to even use the chosen device, I was a pawn in the business of life at that point, a mere intern with nothing beneficial to add 🙄 ), but it was a desperate ploy by the decision makers. After it was tested and still didn't live up to snuff, I was just curious how strong the bond was. The bottom line is solver epoxy is tough stuff, albeit expensive.
And if thermal conductivity but not electrical conductivity is desired, one can add aluminum oxide power to regular encapsulation epoxy.
There is silver epoxy as well. It has excellent adhesion to metals, thermal conductivity, and heat resistance. I've used it before to bond semiconductor metal tabs to solid copper heat sinks, and the device was destroyed before i was able to remove it's metal tab form the copper. (I had to oxy-acetylene torch it to remove it) I didn't really want to have those two bonded in the first place (or to even use the chosen device, I was a pawn in the business of life at that point, a mere intern with nothing beneficial to add 🙄 ), but it was a desperate ploy by the decision makers. After it was tested and still didn't live up to snuff, I was just curious how strong the bond was. The bottom line is solver epoxy is tough stuff, albeit expensive.
And if thermal conductivity but not electrical conductivity is desired, one can add aluminum oxide power to regular encapsulation epoxy.
Actually, aside from tongue in cheek comments, part of the problem is that I'm shifting between amps and preamps without making it clear which one I'm talking about at the moment. My fault. I've had amps on my mind here recently, but we're in a preamp thread and I'm sometimes talking about amps; sometimes about preamps. Obviously amps are going to have much higher Pd than preamps. PVC would be a non-starter for any amplifier but might work--if the tube was vertical and both ends were open--for a preamp. (Bring your old Zerostat out of retirement!) A reasonably sized copper tube on the other hand would definitely work for a preamp, and might even do for a smallish amplifier if you supplied it with fins. Attaching devices directly to a curved surface isn't going to work, obviously, so you'd have to contrive a flat mounting surface.
Grey
Grey
How about plywood? It is a sandwich material and the layers have definitely different epsilon. This would provide required E vector dispersion and bring inoubliable shielding properties.
PMA,
Assuming that you're referring to me, if you or anyone else wants to chip in money--and I mean real, folding, spendable US currency--then I'm accepting donations towards building (more precisely put, having built) a couple of decent boxes.
Anyone?
Anyone?
That's what I thought.
As I outlined in an earlier post, I was heading for a real chassis for once, but got whacked. Perhaps that was too difficult to read. (There's a reason I write 'anecdotal' posts--it's to forestall foolish comments. [It doesn't always work. Obviously.])
I don't build with wood out of choice. I build with wood because it's all I've got. Also, and as I've said before, for all the fact that SC is part of the United States, it's functionally a third-world country. Don't believe me? Pick most any metric you care to name and look up SC vs. the rest of the nation. If it's bad, we're generally near or at the top of the list. If it's good, we're at the bottom. Nothing but plain, sad fact. I guess it's easier to criticize folks when you've got access to good metalwork.
Grey
Assuming that you're referring to me, if you or anyone else wants to chip in money--and I mean real, folding, spendable US currency--then I'm accepting donations towards building (more precisely put, having built) a couple of decent boxes.
Anyone?
Anyone?
That's what I thought.
As I outlined in an earlier post, I was heading for a real chassis for once, but got whacked. Perhaps that was too difficult to read. (There's a reason I write 'anecdotal' posts--it's to forestall foolish comments. [It doesn't always work. Obviously.])
I don't build with wood out of choice. I build with wood because it's all I've got. Also, and as I've said before, for all the fact that SC is part of the United States, it's functionally a third-world country. Don't believe me? Pick most any metric you care to name and look up SC vs. the rest of the nation. If it's bad, we're generally near or at the top of the list. If it's good, we're at the bottom. Nothing but plain, sad fact. I guess it's easier to criticize folks when you've got access to good metalwork.
Grey
I have several fish tanks to heat! 😎
But a little more on topic...what is/was the blowtorchs power consumption?
Regards
But a little more on topic...what is/was the blowtorchs power consumption?
Regards
Without venturing any numbers as to actual wattage, I'd like to note that in a circuit like the Blowtorch a lot of heat is generated in the process of getting a good, pure DC rail. To the extent that earlier discussions indicated a multistage regulation strategy, I'd be willing to bet that the power supply itself consumed at least a third (and I wouldn't be surprised if it was as much as half) of the total power drawn from the wall.
Grey
EDIT: I use water cooling for about 1200W worth of heat dissipation in my big system. It works just peachy. No fish involved, though.
Grey
EDIT: I use water cooling for about 1200W worth of heat dissipation in my big system. It works just peachy. No fish involved, though.
thank you Grey
1200W! there must be something useful to do with that energy. A tank with tropical fish is always a source of enjoyment. 🙂
I'm very curious about Johns design choices and philosophies.
As he mentions heat, I got the idea he wants the parts as cool as possible.
On the other hand, a certain operating temperature may be desirable with semiconductors.
I'm sorry if this has been discussed before,but this is a large thread. 😱
Regards
1200W! there must be something useful to do with that energy. A tank with tropical fish is always a source of enjoyment. 🙂
I'm very curious about Johns design choices and philosophies.
As he mentions heat, I got the idea he wants the parts as cool as possible.
On the other hand, a certain operating temperature may be desirable with semiconductors.
I'm sorry if this has been discussed before,but this is a large thread. 😱
Regards
Juergen Knoop said:
Heat your swimming pool.
The 1200W is surplus from 4 channels of 100W class A that I use to run my mids and woofers (quad-amped system). The rest is air cooled.
Setting aside temperature vs. reliability concerns, it's a good idea to keep things at the same temperature, be that hot, cold, or somewhere in between.
Grey
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