My brother, who worked on gas impurity metrology at NIST, tipped me off to another useful temperature control guideline: 2-3 cm of styrofoam adds about an order of magnitude to the time needed for external environmental temperature change to penetrate into a chamber.
E.g., If one sees an environmental 1º rise resulting in ½º rise internally after 10 minutes, adding that layer of styrofoam will roughly stretch that time out to 100 minutes… or 1000 minutes with double the thickness. > On 2022 Feb 07, at 07:23 , Attila Kinali <[email protected]> wrote: > > On Mon, 7 Feb 2022 13:55:23 +0100 > folkert <[email protected]> wrote: > >> https://vanheusden.com/texts/usb-asic-miner-heater/ >> >> What it is about: I've put my time-servers in a box and now them up >> using usb bitcoin miners (- they have no use anymore because they are no >> longer profitable) to 35 degrees celsius. As expected/visible in graphs, >> this stabilizes the clocks of the time-servers a bit. > > Nice use of recycled electronics :-) > > > Some small additional notes for those who want to do the same and > use it to stabilize oscillators (OCXO, rubidium and the like) > > 1) If you are building a control loop, have a temperature sensor > with more than 0.1°C resolution. 0.1°C is quite a large dead-band > for a control loop in a case like this and might lead to oscillations > in the control loop. I can recommend using a BME280 break-out board > as a temperature sensor. It's relatively cheap (at least it was > before 2020), delivers temperature to 0.001°C with very little noise > (noise floor is below 0.005°C) and gives you humidity as a bonus. > Its long term stability is better than I can verify with the equipment > I have, so good enough :-) > > 2) Use a heating element that you can control with at least 10 bits. > It doesn't really matter whether it's some PWM with 5minutes loop time > or some heater element controlled with a DAC. Going below 10 bit will > give too little control to hold the temperature stable and thus can > lead to oscillations as well. > > 3) If you pass cables through the lid, tape the lid shut. Most of the > heat will be lost through convection through the holes in the lid > > 4) It's not explicitly written in the article, but the small fan you > see in there is cruical. There is convection even in these small boxes > and it is very slow. You want to mix the air inside the box well > so that you don't get temperature gradients and hot/cold air bubbles > that move around. > > > Attila Kinali > > -- > The driving force behind research is the question: "Why?" > There are things we don't understand and things we always > wonder about. And that's why we do research. > -- Kobayashi Makoto > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send an > email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
