Very durable electrolytics or similar?

I thought the solar constant (above the atmosphere) was only 1300W/m^2 or so.

So it is hard to see how it can be more than this at the surface.

Yours is well trained. Mine insists on "Mr. Meter, sir". ;)

Cheers

Phil Hobbs

Zenith insolation at the top of the atmosphere is between 1350 and 1390 W/m**2.

Cheers

Phil Hobbs

Depends where you are and how clean the air is. Pretty murky in the UK today. Car got covered in that saharan dust earlier in the week and it is still hanging around in the air.

About a factor of two high for low latitudes and worse at high ones. The sun barely shows above the horizon here in winter.

The most flattering possible number under the most favourable assumed conditions. A bit like Peak Music Power for low end "hifi".

A reasonable working number for a collector plate at ground level is

Where theta is the angle between the normal to the collector plate and the sun. Extinction affects it badly when the sun is low in the sky (any astronomy site will tell you by how much at what altitude).

If you are interested in this stuff from a practical DIY or research point of view then although dated now "Sun Power" by McVeigh that dates from the 1970's OPEC induced oil crisis is still worth looking at:

Kindle version massively overpriced. Hardback worth a punt of $5 though. I prefer the typeface in my first edition.

You're a long way from the 900,000 hour MTBF required before you can call this thing "durable."

Well OK, I'm not sure... (scratches head.. how could I measure it?) But if it's less it only means that a larger fraction of the heat is radiated away.

George H.

I don't need 900,000 hours.

Ah, you got the military version then :-)

There will be some of that already but it has practical limits. Also, one has to watch disintegration. A few weeks ago when I got my new mountain bike I wanted to head out onto some scarier trails but my old helmet isn't adequate for that kind of turf. So I tried my helmet from the parachuting days, would have been great for the downhill stretches. Tried it on, it still fit like a glove but when taking it off there were lots of crumbles on the carpet. The plastic/foam innards had simply disintegrated.

You failed in 101 electronics and now make an attempt to white wash your failures with this ludicrous idiocies.

Jamie

any photos of this beast?

Sometimes you can get a stainless steel vacuum flask for $7 at Aldi here. If I wanted to make a circuit withstand >300 deg C for a few hours, putting it inside one of those (along with some thermal mass) would be my first attempt. Of course if the circuit has high dissipation itself then this isn't going to help, unless you can split the circuitry into a temperature sensitive part inslde the insulation, and a high dissipation part outside the insulation.

If your circuit is to be put in a box on a metal pole that is stuck in the ground, then I would seriously think about putting part of the circuit inside the metal pole, specifically in the part that gets buried. It is certainly where I would want to put any battery if it had one.

Chris

Sure you do, unless you're satisfied with less than 50-50 chance of making it 10 years.

You need to look at the difference between lifetime and MTBF. It is not the same and the relationship between those two is, for most technical gear, not at all linear.

I'll snap one on the weekend and post here in the NG. It is in its drill press stand right now (which is of roughly the same vintage) but a heavy test setup is in front of that and I'd have to move it.

That is exactly the problem, nearly always. While forced air sounds like a straightforward solution it usually isn't when it comes to stuff that has to run unattended for years. You can't have fans or anything that could potentialy clog up. Things must be kept simple.

No battery. Poles and other structural parts are typically off-limits because that would make an installation unduly difficult.

Yes, Nichicon was in selling their wares yesterday. I specifically asked what their "lifetime" was. It is *NOT* MTBF, it is the life of the capacitor where they guarantee their failure rates and capacitance/ESR curves. The increased lifetime factors for capacitor temperatures under the specification was 2x/10C for the aluminum caps and 6x/10C for polymer caps. They also said that it didn't matter whether the capacitor was biased or even the ripple current (within spec). The only thing that mattered was the temperature and time. Obviously, ripple current forces the temperature up.

all this thing "durable."

ng it 10 years.

And of course capacitor MTBF is far different to complete assembly MBTF. In simple terms, if you had 10 caps each with 100,000 hr MTBF plus 100 other parts with 1,000,000 hr MTBF, your finished assembly would have had on aver age 5 cap failures and the occasional other component failure by 100,000 ho urs.

NT

That is exactly how I remember it. Regarding ripple current I try to keep that way lower than spec and have a ceramic bypass for the fast stuff, makes the caps happy.