Two (possbly pointless) 200p mods

[8472]

As the weather, astro-wise has been shocking lately and my new (to me) 200p has been sat idle at the end of the lounge, I thought i'd set about a couple of mods i'd been meaning to do.

As a few of you may know, with the limited observing time i've had with my new scope, i have not been all that impressed with the supplied straight-through finder and the contortionist skills required to use it. As I am way too tight to buy a new RACI, and as Santa is (apparently) getting me a Telrad (if they ever get any stock), I set about making my own bespoke RACI attachment for my straight through finder (don't laugh).

I made a steel box section with a 45 degree surface at one end, to which I mounted a small mirror inside, to reflect the view from the finder to a much more user-friendly angle. It's not the last word in finesse, but will tide me over til I get a better solution. It's spray painted black, with some padding and insulation tape on the inside to prevent the finder getting scratched, when it is fitted. Time will tell if it actually works at night, but it seems to pick out a few rooftops I was pointing at, quite nicely.

My first mod though was simply to fit a 12v 120mm fan to the primary mirror end, to aid in cooling down times for short observing sessions.

I simply cut a hardboard baffle, on which to screw the fan to, and cut the outside diameter so it fits snugly inside the counterbore of the OTA end housing. There is a video (on FaceTube, i think?) stating that the baffle needs to sit on the outer edge to pull the warm air down the inside of the tube and around the mirror, and out the back - not simply cool the back of the mirror.

As for the issue of how to power it, I was seriously considering converting a spare heavy-duty car battery into a power tank, (some good guides and ideas on SGL) but ultimately, couldn't be doing with the idea of lugging around more paraphernalia.

After unsucessfully experimenting with various batteries, I had an idea of using the battery from my broken old DV camcorder.

This provided a nice output of 7.4v (enough to spin the fan effectively, whilst trying to minimise noise and vibration) and enough juice with 800mah. I've an even larger 3000mah battery, which should prove to run all night, if I ever feel the need to use it.

No doubt time will again tell if it generates enough vibration as to effect the view through the eyepiece. If is does, I have a couple of 7w 22ohm resistors to slow it down more, if need be.

Hmm - what to tinker with next?...

Kev

[Doc]

Dobs are all about tinkering so well done they look like great mods.

[Daz Type-R]

Nice one on the diy and if they dont work, back to the drawing board.

[8472]

Cheers guys - as I said, time will tell.

Yep, as SWMBO will testify, I'm always trying to tinker and "improve" stuff. Not always successfully though, i might add.

No doubt the car's relieved I've found a new thing to "improve".

LOL

[catman161]

Great stuff well done cooling fan is my next mod. I get paid tomorrow so may be off to maplins

[8472]

I'm pretty sure I've one or two old 12v fans lying about somewhere I've no use for.

Probably covered in dust though and only 80 or 92mm?

[Cazz]

I like the finder mod, a clever idea. Lol about your car being pleased, that made me smile, I bet our campervan is also thinking the same thing lol.

[catman161]

I'm pretty sure I've one or two old 12v fans lying about somewhere I've no use for.

Probably covered in dust though and only 80 or 92mm?

Thanks for the offer Kev but already had the fan just the other bits and bobs from maplins