DIY all-sky cam?

[Gonzo]

thanks, gona have to build one to run under 5v.....

[Gina]

I've got some 10 ohm 3W resistors on order that I'm planning to use for dew heaters.  Running off 5v they will dissipate 2.5W each.  Remains to be seen how many will be required.

[Horwig]

I have about 6W dissipated by my dew heater, where's the 5v coming from for the dew heaters , USB, or psu? If it's usb you're in danger of overloading it

Huw

[Gina]

PSU from an ex PC in my case.

[NEM]

How about some sort of over centre spring arrangement (if that's the right term) so that a gentle push flips it one way and a gentle push the other way flips it back, then you wouldn't need any motor stalling to keep it open/shut, bit like a sprung rocker switch.

Dave

You could use two small magnets, one fixed to the centre point of the travel and the other to the frame and aligned to repel each other.  A small push would switch the sides and the repulsion would keep it in place.  But of course it wouldn't be fail safe if the power went off with the filter open and the sun came up.

Noel

[JamesF]

But of course it wouldn't be fail safe if the power went off with the filter open and the sun came up.

I think that's the real issue here.  If the power dies completely it needs to revert to the sensor being covered without needing power.

James

[Gina]

Absolutely, and that's what's causing the headache, it would be easy otherwise.

Wish I could remember my physics then perhaps I could work out how many turns of enamelled copper wire I would need and what size to buy etc.  As it is I think I'll just buy 2 or 3 different gauges of wire and have a play.  Plus it's a case of finding "any old iron"

Later...  Ordered some 0.1mm and 0.4mm wire - should be here Tuesday.

[JamesF]

If all else fails I'd probably use a nail for the core.  Ok, so it would probably be steel, but I'm sure it would do the job.  I'd have thought a wire gauge somewhere in the 20s would work ok?

James

[Gina]

Yes, one of the sizes I'm getting is 26SWG I think this will be the one.  The other comes out at 38 gauge and is very fine but OTOH I will be making a very small solenoid (if I can manage it).

I have two possible ideas - one is a 3mm axle going down from the cam PCB and the other to fit it in the lens to PCB enclosure where there is very little space.  I think the former will be easier and use larger conponents.  It's not really necessary to go "microscopic"

[Davey-T]

You could get one of those old door bells and mod it.

Will magnets interfere with any electrical circuits ?

Dave

[keithatrochdale]

Hi How about using some Muscle wire?

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/General/TCF1140.pdf

https://www.sparkfun.com/products/11900

.

[Gina]

Hi How about using some Muscle wire?

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/General/TCF1140.pdf

https://www.sparkfun.com/products/11900

.

That looks good - have to see if I can get it in the UK.

Yes - found it - Proto-Pic just a couple of quid   Ordered two different sizes (otherwise the postage would have been a lot more than the item) 0.005" 200mA current to operate and 0.012" 1.5A to operate.  I'll try the bigger size for other applications.  Worth buying for the interest

It will certainly be interesting to see if this stuff does the job.  I'm just a little concerned about powering it all night but we'll see - not much cost anyway - total for both sizes with delivery and VAT was £5.10

[Gina]

Been making new case parts to accomodate the smaller dome.  First two photos show a test rig to see how the lens height worked out in the dome as it wasn't possible to measure directly.  It's too low.  Third photo shows just the outer tube slid onto the camera support frame to give a suitable lens height. 

I shall be making a conical part to attach to the ali tube and a longer outer tube to cover the works.

[DIYASTRO]

Just a thought.... To save making coil haw would one of the small reed single pole relays do? you can slip the reed out of the coil, its pcb mountable , around 700 ohm resistance and is around 25mm long and 6mm dia. I have made coils myself from coated fine copper wire and its a pain!

Smaller coils are found inside some old slr cameras for there shutter mechanisms.

Advantage of the reed relay coil is a ready made round hole for the ferrous core to be cemented in.

Boyd

[DIYASTRO]

Forgot to say in last post... another source of small coils.... 2 are available inside the small stepper motors 5volt! used in old pc 3.5 disc drives.

they measure around 13mm diameter with a core hole of 7mm and only 3mm thick. May make up into a nice 'button' solenoid!

Boyd

[Gina]

Good thoughts - thank you Boyd

[keithatrochdale]

That looks good - have to see if I can get it in the UK.

It will certainly be interesting to see if this stuff does the job.  I'm just a little concerned about powering it all night but we'll see - not much cost anyway - total for both sizes with delivery and VAT was £5.10

Hi thought you would like it!

Will it give off enought heat to be useful in keeping the dome clear?

.

[Gina]

I wondered that too but I think not.

[pete_l]

I've just tweaked the focus on my all-sky cam. Here's a sample:

Briefly, the camera is a LN300 Exview running at x512 accumulation (10 seconds) with a lens from the QHY5

accessories pack from Modern Astronomy. The PAL video feeds an Ezcap grabber which is sampled every 10

seconds by some freeware called Chronolapse on a Windows7 box.

The camera is "naked" - no dome and is on a 6 foot wooden pole, just above my "playroom".

North is to the top, East to the left.

Vega is visible near the centre and Arcturus is the bright star neat the right-side at 3 o'clock.

Sagittarius is just visible at the bottom and there are 6 stars visible in Corona Borealis (between

Vega and Arcturus) so I reckon I'm getting visibility down to about Mag 4.5

[Gina]

That's superb

[JamesF]

It is indeed.  I love that the Milky Way is so clear.

James

[Gina]

Now have the new casing and internal supports printed and the QHY5 and lens unit installed within, ready to put on the mast, except that there's no shutter control yet.  I have the mast (AKA 1" ali tube) mounted on the NW corner of the obsy ready to take the camera, so I'm hoping to try it out tomorrow (oops later today ).  It still needs weatherproofing around the dome.

Almost certainly I will need to reprint the internal framework later when I've worked out the shutter control.  Unfortunately I don't expect to have the bits to do that until Tuesday.

[Gina]

I may want to make bevel gears for either the shutter control or the focussing.  This link explains how to draw bevel gears (amongst others) in SketchUp.

[ncjunk]

You are a star! I've been thinking of where to get that gear info and you've posted it here. I can go back to daydreaming now.

Sent from my XT1032 using Tapatalk

[Cath]

For moving a shutter I spose you could maybe try the head moving coil/magnet from the inside of an old laptop hard drive?

Or maybe a discarded DSLR mirror flip solenoid or DSLR shutter - of which I'm sure you have plenty of Gina