expected low of 1 degree and with a high pressure system about to park itself over the state, I can finally measure the peltier cooling system.
I hope to have the new one up and running in a couple of weeks, so i can then run the test again.
The current one has only one peltier, there is no perspex insulator and the aluminium cold plate disc is too big to fit inside the mirror cell cavity behind the mirror.
The new one will have two peltiers, a perspex insulator that will seal the base and also the cold plate will fit in behind the mirror.
Hi Dave, I'm watching ..... and waiting .... I would have expected the mirror to be diving closer to ambient by now, with the cooler that is, how long does it normally take?
Regards IanG
Hi Dave,
I'm very interested nice you are giving us a live update! Since 20:00 mirror and ambient are tracking closely, I assume without the peltier the mirror would be much warmer over ambient?
Regards IanG
Peltiers only generate a relative temperature difference between their hot and cold sides, so if ambient air temp goes up by a couple of degrees then the cold plate temp will also go up a couple of degrees.
Normally this is a good thing, as the ambient temp drops through the night then the cold plate temp is always a few degrees colder than it. But when clouds come along like this it can spoil the party unless you can engage more cooling to compensate.
Yeah, with the peltiers running they can exaggerate thermal currents, cause they are adding a very cold layer of air around the mirror. It seems to take at least 15 minutes with the peltiers turned off before the air and mirror settle down. Just long enough to go and make a cuppa hot milo or coffee at 4am :-)
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