Ok, it is finished and already i think i have much more to do.
The peltiers cool quickly on one side and heat quickly on the other, but within 10 seconds, the cool side is no longer cool and the hot side gets hotter. This thread is probabley aimed at the resident mirror cooling expert, but I am thinking i need an insulator to maintain the cold side or the hotter side interferes???
I bought the .6mm alu sheet from bunnings, fans and peltiers from the local jaycar.
I will keep playing and then form a template to form a kit for anyone else that wants to make one!
DP you will need an insulating layer between the hot and cold sides, I used a disk of 3mm thick perspex for the job. Cut out the square holes for the peltier(s) to sit in, and it does a stellar job of keeping the two halves separated. It's *just* thinner than the peltiers, so there is still guaranteed contact between the peltiers and the hot/cold plates, and you can run nylon bolts through from one side to the other to hold it all together. (Nylon bolts are better than metal bolts cause they dont conduct heat, but they're not as strong so you need more of them).
When you cut out the holes for the peltiers in the perspex also add extra cuts where the wires come out of the peltier, otherwise you'll have to bend the wires too much and the peltier may get damaged.
Hi David,
Yes, you do need to insulate between the cool and hot sides, a piece of thin polystyrene foam sandwiched between them should be sufficient with a cutout for the module to fit though. Envisage the thermoelectric device (peltier module) in an Esky, there is about 20mm of insulation between the cooling bit inside the unit and the heatsink on the outside. The unit I fitted into to an Esky had an extension aluminium section to allow for the thickness of the Esky wall it was inserted through. Ican scan a picture and send you via email if you like tomorrow evening.
The fan should blow onto the heatsink too not the other way round.
Regars IanG
thanks ian, i have a few heat sinks, but not attached yet and yes the big fan is sucking not blowing. (i knew that ..... i was just testing you all of course....)......bugga!
i reckon i may have to come for a visit to the holy mecca of shed and tools!
i have already killed one peltier, where would you get perspex and nylon bolts from?
Hmm, I just fish around the yellow pages until I find stuff, you're looking for a plastics manufacturer for the perspex and a trade supplier for nuts & bolts ought to have the nylon variety.
Hi David,
Yes, you do need to insulate between the cool and hot sides, a piece of thin polystyrene foam sandwiched between them should be sufficient with a cutout for the module to fit though. Envisage the thermoelectric device (peltier module) in an Esky, there is about 20mm of insulation between the cooling bit inside the unit and the heatsink on the outside. The unit I fitted into to an Esky had an extension aluminium section to allow for the thickness of the Esky wall it was inserted through. Ican scan a picture and send you via email if you like tomorrow evening.
The fan should blow onto the heatsink too not the other way round.
Regars IanG
Yes, polystyrene would also work although it's not as mechanically strong as perspex so you'd have to be careful in handling it.
One more thing... In the later versions of my cooler I made the perspex disk about 2cm oversize all the way around. This has the effect of directing the hot air away from the scope and the cold side. The perspex disk the effectively closes the end of the tube and makes the cooler more efficient.
In the early versions I was having trouble with the hot air off the heatsinks getting back into the tube and playing havok with the scope.
All very interesting, and it's great to see the learnings of the tasweigan one.
Once you've perfected it all, i'll be happy to try my own I still need to start with simply temperature monitors, which reminds me, I need to get in touch with wombat_in_space who was possibly going to make me a unit.
I'm with you, Mike. Sitting back, watching our Apple Isle correspondant with great interest and delight. I also would be very keen to get my scope "chillin'" sometime in the near future.
Also, like you, I think I'd need someone with a little tech/sparky background to whip me something up.
Maybe if there were enough of us all wanting to get into it at the same time we could get multiple units made at the same time? Might work out more economical for whoever's making 'em?
Maybe if there were enough of us all wanting to get into it at the same time we could get multiple units made at the same time? Might work out more economical for whoever's making 'em?
once this one is finished and working, i will approach mick pinner to see if he can quote the aluminium cutting and drilling and then see how many people are interested in the final cost.
I have also just bought a new Jaycar temp monitor that they sell for cars. It has two temp sensors (1 for ambient , 1 for mirror), voltage of the battery, battery level and ice alert.
So all in all, jaycar can provide fans and peltier and hopefully nylon bolts...kit it up in a bag. I am thinking most 10" bases / cells are similiar in positioning of the collimation screws and the thread size if the locking screws. If not a few different versions may have to be made???
Dave, there is a place in lonny that can laser cut aluminium at Mowbray. They also do powder coating. I have had work done by them and the finished results are very good (perfect is a better word). Might be worth contacting them as well. I can't remember their trading name but will check next time I'm out that way.
For top class aluminium work you could try Gary Mitchell in Sydney, he did all my aluminium work and it's first rate quality and also very reasonable cost.
You can get him as gnmitch-at-ozemail-dot-com-dot-au or look up his number in the white pages. He has a workshop in condell park near the airport.
Hi David,
1. Nylon nuts and bolts are available at **** Smith Launceston, I have purchased them for mounting power transistors to heatsinks, may also be at the new Jaycar shop.
2. Polystryene is a better insulator (has a less thermal conductivity than perspex I'm told). If sandwiched between two aluminium plates one the cooling vane the other having theh the heatsinks and fan attached it should be pretty stong, if not try the perspex. It is actually better if the insulation protrudes further out (about 10mm) than the diameter of aluminium sheets. It lessens the thermal feeback due to air flow around the diameter or edges.
3. If you have the aluminium powder coated make sure there is a bare patch where the peltier modules mount, the powder coating will effect the close coupled thermal conductivity required between the module and the aluminium.
Hope this makes sense. Good luck with it
Kind regards, IanG
(sorry, couldn't resist; i'm so happy with my dob these days 
)
I still need to start with simply temperature monitors, which reminds me, I need to get in touch with wombat_in_space who was possibly going to make me a unit.
