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NickK

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Everything posted by NickK

  1. Just got an upgrade from a 2009 3GS to a new iPhone.. so this works nicely with a VNC client too:
  2. Question.. should I bother bringing my 300mm f4 .. last time it did really nicely with m51. Just means I have to sort out the mounting with the new wifi for the automation sat in it's normal position. Think I may choose to simply single scope it this year.
  3. Having built the stepper auto-focus.. an alt-az polar alignment system for the NEQ6 and INDI would also be interesting! Only thing it needs the base replacing todo it (the way the screws work is prehistoric).
  4. So I've had a play over the last couple of nights - including leave the laptop running (30mins per frame! CPUs are slow!) then used PI drizzle stack and autostretch: The PNG looses it a little (the PI 64bit version is a little more subtle on the noise square (I've yet to sort out the noise level adjustment so this is with noise). The two galaxies have appeared with some additional shape (in PI and a little above). I've also optimised this a little (hence only 30minutes!).. but there's still some more to go in terms of algorithm and optimisation.
  5. The DRV8824 is a current limiting chopper driver so you can use (and I do) 12V with a 3.8V stepper (670mA), there's a formula that allows you to set the current limiting using the reference voltage (use a volt meter when adjusting the potentiometer). It's been operational for hours at a time indoors and the stepper remains stone cold. The 12V means the back EMF on the step is overcome and you get a very very good step.
  6. yup if you can select what parameters you'll need ahead of time then you know you won't need all the indices.
  7. Think I will use the 105 scope but also do what I did last time and use the old FD 300mm F4 camera lens. Simply put it gives a great wide field image the only issue is manual focus at the moment but I have a plan...
  8. NickK

    Things to bring..

    So for me Tent + canopy + carpet Air bed (has pump inside) + radiator foil + 2x 16A 4x13A RCD + Electric oil radiator (her) Gas stove, tin open, black bags, table to keep things off the ground (wildlife)..
  9. Just been checking that the Odroid C2 based control is still working.. oddly because it doesn't update easily.. it's working just as I left it.. #trythatonwindowsandmac
  10. I had an old 128GB first gen SSD laptop drive, using an SATA-USB it works nicely as an SSD/longer term storage and my C2 eMMC then runs everything else.
  11. Also some experience in ardunio with fast/accurate timings. I tried to write my own current limiting chopper driver version using the arduino uno - this worked about 20kHz rate maxed out however things like the serial output that communicate via USB etc cause a massive change, even minor code changes or conditional execution cause timing differences. This same issue also causes problems if you're attempting to implement micro step using the arduino rather than a micro stepping controller - and even if you're using the serial in the same loop as the 150 steps/sec pulse rate (given 10x safety margin to be accurate with the step rate). The arduino uno/nano will cut it I think without needing too much in terms of clock crystals and floating point (very slow in arduino) but keep the loops static or use the accel-step library... My stepper is a NEMA17 with a 100:1 gearbox for my focuser then using a DRV8825 and the arduino uno - this is the stepper & gearbox I'm using: http://www.active-robots.com/3322-0-28sth32-nema-11-bipolar-stepper-with-100-1 however note 1.8deg/step (200 full steps/rev of the stepper), there is a minute amount of play in the gearbox (will always be), and it has a crazy amount of torque (I hang my astro photography gear off my 1:1 focuser connected direct to the gear box. Points to watch on this stepper are - it's a 3.8V 670mA bipolar unit. However you will need a something like 12V to ensure that the back emf when stepping occurs - the DRV8825 allows 12V to be used to power the 3.8V stepper (connecting direct will cause it to burn up) as it chops the current at a very high rate. The result is that the stepper remains cool for the entire time even when the load of the scope's filterwheel+cameras etc are all pulling against it through the gearbox. The system will step 1/32 without a problem and I can't stop it by pinching the gearbox shaft (and the steppers side shaft is quite forceful too!). Although my calculations are for my focuser in my DIY YAF robofocuser thread.. Note - NEMA is the form factor not the standardised specs so two steppers can have different stats but be NEMA17 sized.
  12. I'm going to probably offer some, well not directly useful, advice If you're tracking then you're looking at a certain speed in arcsec/sec. However for each step when you've got gears you have a little play caused by the gap in the meshing, this causes a ±error and that may vary as the mount goes over the zenith. In sensors you're looking at 10:1 ratio, i.e. being able to measure .1 unites to be reasonably accurate for a 1.0 unit scale. So rather than looking at a 1:1 speed, I would look at 10th speed gearing and then run at 10x speed. The reason is that it's going to be smoother with 10 steps between pixels than 1 step every 10x the time period. This is todo with the object position on the CCD rather than the gearing etc (i.e. reducing the motion blur effect). I did say it's not particularly useful
  13. I got annoyed with Parallels when (without warning) an OSX update caused the thing to stop working.. their answer is to buy the next release. So I use Virtualbox.. (old version used to have a USB-multi-core issue) and now I just use an ODroid C2.
  14. NickK

    Things to bring..

    I think we should have a things to bring thread (actually it seems there's one every year).. as a help to experienced and first time SGLers Bed to get you off the floor of the tent.. although probably not -10degC in october!
  15. Careful with these on a few accounts: * Power issues - voltage drop over distance, cameras that use USB power may start behaving differently or not work at all. I find that if you do have an extender/long USB cable then a powered hub is best at the remote end. * USB2.0 - which means it will drag the entire USB channel down to USB2 supported speeds. * USB protocol interactions at a driver level may have issues - especially if there's timeouts on the USB packets or responses as the system may be retrying more. Now it depends on your camera, drivers, and other hardware setup.. Although from being involved with camera USB drivers - some CAT5/6 based extenders work better than others.
  16. Hehe or use the massive 22Kg Bosch S5 100Ah battery I have.. However the cameras like 13.5V as they have less noise..
  17. Nope.. something like 80mm.. of some stupid (and unrealistic) precision! But the main thing is that it will work, however things like backlash and other inaccuracies will have a far far bigger impact
  18. Yup - basically you'll have RCD protecting the 4gang, the 16A cable and then the site RCD protecting the supply again.. You could (if there's spare site plugs) use one for the astro gear and one for the tent gear.. that way if you accidentally trip the tent one .. the astro gear carries on.
  19. I've used this - there's a DRV8824 and 8825 - the difference is in how much current they can pass through. The reason I went down the DRV route is that they can cope with a far higher voltage that helps cope with overcoming the back EMF. I use as 2-3V stepper with 670mA max - the result is very good - even at 1/32 with the stepper connected via a 100:1 planetary gearbox then to a 1:1 focuser. The result is about 1.6million steps for the focuser travel and that is with a full set of astrophotography kit. It may be worth putting limit switches as the torque can be quite high.
  20. Insurance too.. if it's a prototype, typically there's a need to ensure "oops" breakage and "argh" disappeared insurance. I have my scope on personal possessions - so it's covered for things that the home insurance doesn't cope for. Like being in a field away from home..
  21. Couple of things to look at with the small system builds: * write rate - micro cards are ok, although eMMC may be faster still * USB power supply - this may not cover the full power required by passive hubbing. The power chip used may not supply enough for the hubs on the board. * vibration - I decided on a C2 (no fan and passive cooling) and an SSD for big storage (128GB) My C2 build:
  22. The obvious bit with those lenses is the need for post processing if the wave lengths aren't focused otherwise there's a scatter effect that needs subduing. I thought about these with the old school plastic ones but to be honest it's a bit out of DIYer capability to produce I'll have my hands full with my ODroid automated setup!
  23. Very interesting - would love to chat about it.. looks above you have a focusing model for different wavelengths..
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