Friday, July 15, 2016

20160715 Sun

Got a half day off today with the kids, found that the sun could be seen from another room with a less desirable angle, anyway, why not?

Pull out everything and went to another room, the view was a bit blocked but still do-able.  The JMI focuser controller is oh-no, low battery and cannot move at all.  Removing four screws and replace the battery is time consuming, the sun was going away.  My Teclast was low battery, too, just 7% left... what's bad is that, I couldn't charge it and use the USB port for my cheapy bw cam at the same time... So, I took the plunge and do it all without all those adversities.

Click for full size, taken at 0724 (UT)... T-max does not tuned well, aligned with only a single point, i.e. AR 2565.  I had just ordered an ASI 120mm (again) in the hope to get better image, let's see.  Why I was selling that was due to the Newton's ring, and my current bw cam got Newton's ring too...

Saturday, July 09, 2016

Motoring the DEC axis of the Sky Adventurer mount

Found suitable gears and motor, installed them right away.

Step one: try to find the suitable location for the motor for correct gear meshing, fix it with a tape:

Then, use some instant glue to fix it in place, add hot melt glue to further reinforce the position.

Finally, solder cables and also standard jet for connection to the controller box.  Add hot melt glue to insulation the bare end of the cable.


A short clip before the soldering work to show the gear meshing:

Sunday, June 26, 2016

Enhancing the Nexstar mount

Last time I pulled the whole setup to a nearby playground, I managed to put the OTA, the tripod and every accessories inside a medium sized backpack.  And the Nexstar mount was placed inside another bag.  It's very portable indeed.

The backlash has to be adjusted further for high power imaging. 

For the power, I used 8 AA rechargeable batteries, and it gives ~2400mmAh at around 9.6V, after playing for around two hours, I guess only 50% power was left.

I've tried to fit 3 pieces of 18650 inside the battery compartment last time, and it's even smaller than 8 AA!  So I took the plunge to remove the original battery box and replace it with a 18650 battery box.

With higher quality 18650, say 3400mmAh (measured by myself), now I've 3400mmAh at around 11.1V so it should last even longer.  With my current charger, I could recharge them at once, instead of two times (i.e. four at a time), and it's much more efficient, too.  The cost of the 18650 is similar to AA rechargeable, by similar, I mean the cost of one piece of 18650 is similar to that of the cost of one piece of AA rechargeable!  So, the overall cost is less than a half.

And it's lighter too!

The modification is simple and even reversible, just some very simple soldering work.

Friday, June 24, 2016

20160623 Nam Cheong Playground Planet Imaging Night

I had virtually stopped planetary imaging after the shut down of my home@walnut observation point inside my home.

Tonight, I pulled out my C5 with the Nexstar mount to a nearby playground for planet imaging.  While most people were jogging (I use to jog there too), I took a seat on the grass and started imaging.

I feel like an idiot since I spent long time just to center my targets enough for imaging.  I still remember that I could do imaging with my C8 at f/50 but now I found a hard time using my C5 at f/20!

This is my mobile imaging station.  There is a tiny Gitzo G106 below, and a small projector metal plate to support both my Nexstar and my 10" Teclast Windows 8.1 tablet with a keyboard.  It won't be very stable as expected.

Transferring huge AVI files for imaging processing is slow.  My first target was Jupiter but then the processing of Mars was faster.

1345 (UT), this is stacked without further processing basically.

1347 (UT), this one is aggressively processed but it does not help much, maybe even worse... anyway.

Both taken with my C5 with a Tele Vue 2x barlows.  Without a IR blocker, the image is no good as expected.

Jupiter C5 at prime focus, 1308 (UT):-

With 2x barlows, 1319 (UT):-

Much worse than what I could do previously with a C5, I shall practise more.

Wednesday, June 15, 2016

Potential power source for the Nexstar mount

I had been using 3 pieces of 18650 in parallel to provide power to my Nexstar mount via the external power socket.  The internal AA battery compartment is also used as a backup source.

Last night I tried to pull out the AA battery compartment and I found it easy, it was just fixed there using double side sticky tape.  I tried to fit in my 3 pieces 18650 battery pack there and it has more space than enough, and such a modification is easily reversible too!

It even has enough space for a electrical coupler and thus no soldering required.  I'd love to find/make a replacement battery cover after the modifications.

Monday, June 13, 2016

Counter weight solution notes

Time to DIY something just in case...

The Star Adventurer has a M8 threaded hole, while my self adapted Mark-X has a 3/8" threaded hole on the other side....

I've a compact metal shaft with a 3/8" male thread, and 15mm diameter, no stopping screw or safety mechanism.

Just a note.

Field Power

Years I ago, I have a SLA battery which is powerful but extremely heavy, and then I made a bracket to use it as counter weight.

Later, I used 18650 batteries and it's much lighter.  And it's about as powerful as SLA.

Recently, I used USB power banks and it's even more compact in size, and it's airline portable too!

Problem is that, some USB power banks will stop delivering current, maybe they want some sort of hand shakes between devices.  I found a very old USB power bank which will keep on kicking with any load, and this is great.

The Sky Adventurer was now powered directly via USB, the Nexstar mount is powered via USB to 12V cable, and the GOTO Mark-X is powered via USB to 9V cable.  Very neat and portable!

GOTO Mark-X further modifications

It could be the only mount that I had, and could hold a bigger OTA!

I took the controller out, and modify it a bit to accept center positive power cord, and I could power it via my USB to 9V cable.  The current draw is about the same as it states, less than 200mA.  Funny is that, if you pause the motor, the current draw is maximum.  4X speed does not increase the power drain, too.

So, I also pulled out my Sky Adventurer base to fit them together.  I've used a simple tripod quick release base to match the 1/4" of the Mark-X, and it's a perfect fit.

No more need to use that 410 geared head for this purpose, this is also lighter and more accurate.  If I buy a strong tripod, plus adding a counter weight mechanism, it could take a C8, I believe.

Guess what, I always want a C8 after selling it.  But right now, I don't think I have the time and energy to have one yet, or otherwise, I will buy one immediately.

Monday, May 16, 2016

Nexstar 4/6 SE mount power comsumption

I bought a small USB power meter, and I sandwiched it between my USB power bank, and the USB -> 12V cable which is connected to my Nexstar 4/6 SE mount.

It was drawing 0.51A at 5.14V which is less than what I imagined.  When both motors were slewing at maximum slewing speed, it measures around 0.8-0.9A only!  Therefore, a USB power bank should be enough for a whole night of observation.

Fixing the Sky Adventurer

My Sky Adventurer was getting harder and harder to turn... it was kind of stuck even if you totally disengage the clutch, it won't turn unless you really force it.

On opening it, the problem was nearly shown, see below:

there was a circular scratch mark on the inner rotating axis!  Obviously, it shouldn't be there and it should be caused by some metal dirt or uneven machining?  So I cleaned up the surface and found a few small marks, they're so small that even if you touch them, you won't feel there's anything... I bought the finest sandpaper to sand those stuff down, and then put the inner axis in, rotate it a few times, and there are two dirty patch will form, and then I sand them down again and again.

Finally, they were gone.

You couldn't trust your finger, you won't feel it.  But if you turn the inner axis with it, dirt patches will form.  So after a few runs, they were all gone!

The gear was not machined very nicely, and I sand down those rough edges like the one which is shown below:

Placing some grease back (thank Eric Ng), and now it's very smooth!  The machining is not bad afterall, when I put the inner axis back even without grease, it feels like pressing a syringe! 

I'll them it along for camping and stargazing trip soon!