Crystal oven theory

Heaters usually run at some limited full power after cold-start, so the initial temperature curve is linear, slew-limited. If you have a well-tuned PID loop, the integrator rails and it will usually overshoot at the end of the slew. That can be fixed but it's usually not worth the trouble.

snipped-for-privacy@highlandsniptechnology.com wrote in news: snipped-for-privacy@4ax.com:

The foam is for physical shock absorption, silly.

Hard to protect against that "floating in air". They should try some nice aerogel inserts. I think it has pretty good thermals compared to foam.

I just did some tests and noted the heater power.

None of my ovens depended on foam for mechanical support. Sometimes long lead wires are bad news too.

I did mount one OCXO on some custom springs. Mating and unmating an nearby SMB test connector made my PLL lose lock.

Have you done that? Is aerogel rigid enough to support a subassembly? Would mechanical shocks scrunch it down?

My definition of over-compensated would be indefinite oscillation, which is what I was concerned about when I was monitoring the behaviour... No theory involved!

mandag den 23. maj 2022 kl. 17.46.31 UTC+2 skrev snipped-for-privacy@highlandsniptechnology.com:

snipped-for-privacy@highlandsniptechnology.com wrote in news: snipped-for-privacy@4ax.com:

subassembly?

The word for today is scrunch.

I don't know. it isn't a foam. so scrunching of any kind would be a different animal with it. One has to wonder how it reacts to thermals though.

There were/are several ISS exterior exposure tests taking place. For micro-meteor impact data and I think there were some thermal tests.

Someone will make some carbon nanotube matrix thing that beats it all because we will be able to shape it. Oh wait. that's conduction. even electrical. They could come up with an idealized resistance medium and make big high wattage "carbon comp" resistors again for certain applications. Less noisy than what we used for so many decades. Or, a nice 'clean' noise... the sound of things going bump in the night (day too).

Insulation... right. Aerogel. Maybe they make a Hydrogel or Nitrogel. Or Xenon... apply juice and get a glow gel.

Some aerogels are foam-like quartz, quite strong enough for most uses, and relatively tough. You could use 'em to support, and they're good in vacuum (if you want a good insulator, ditch the air). On the other hand, a perforated section of fiberglass PCB should likewise be a thermal break. How stingy on heater power do you want to be?

John Dope snipped-for-privacy@message.header wrote in news:t6gdmo$or8$6@dont- email.me:

Widlar was an engineer, idiot. Consider yourself 'flipped off'.

You have to be a complete idiot to search and not find Widlar info.

The usual terminology would be "underdamped" if it's linear, or "windup" if it isn't.

Cheers

Phil Hobbs

The foam inside the HP oven is stiff & brittle. I think it may just be to separate the bits from each other and provide mechanical support, but I don't think I'd want to rely on it to absorb much shock.

Basically the consistency of dehydrated "astronaut" ice cream if you've had that stuff..

The way I would describe the "insulating" (or whatever it does) foam in the HP oven is sort of the consistency of freeze-dried ice cream.

bitrex snipped-for-privacy@example.net wrote in news:QaTiK.4601$ snipped-for-privacy@fx40.iad:

Compared to being suspended in air, I am sure it wil absorb more. Just what do you think "mechanical support" is?

Do u require mechanical support:

Dehydrated ice cream? I'm glad I didn't become an astronaut.

Yeah, freeze-dried. No idea if this stuff was actually used on space flights or when. My mother used to buy it for me at science museum gift shops when I was a kid, we didn't have much money but she didn't like to turn me down for a few souvenirs so long as they were "educational"!

It was sweet at least and most sweet stuff tastes good to an 8 y/o:

The pull-back racer Space Shuttle toy was another classic gift shop crowd-pleaser.

Heater power is seldom an issue. Heat loss is bad because it makes an assembly non-isothermal, so that some bits are not at the same temperature as the feedback sensor. And the difference will vary with heater power, namely ambient temp.

On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon snipped-for-privacy@mjcoon.plus.com> wrote in snipped-for-privacy@usenet.plus.net>: