pmlogg

While looking for information on autofocusing I came across the "4tronic RFU":  https://shop.4tronix.co.uk/collections/astro-electronics/products/bundle-auto-focuser-focus-rfu

which seems quite a versatile product.  The 4tronix website says it can also control stepper motors by use of a £5 adapter (currently out of stock):  https://shop.4tronix.co.uk/collections/astro-electronics/products/stepper-adaptor?variant=41779684147379

As I have one telescope with a DC focus motor and another with a stepper motor so this seems to offer a way to be able to control either focuser (not both at the same time) via the same connection back to the computer.  It made me wonder whether the same 4tronix adapter might work with other astronomy DC motor controllers such as Shoestring Astronomy's FCUSB or Televue's FocusMaster?   The FocusMaster controls a DC focus motor that seems very similar to the Stargazer autofocus motor, comparison image attached.  With the Televue version the offset axis of the motor lets the user rotate the motor in its mounting bracket to allow manual focusing.  I'd be interested in members views on the 4Tronix adapter and on the Televue /Starwatcher motor similarity.

I think I asked once before but does anyone have information about the Pulsar/Rigel motorised shutter system for the original type of Pulsar 2.7m dome, i.e. with the two-part shutter?  I did ask Pulsar but they couldn't help.

All I have been able to find is an advertising image of the control box.  Images or a copy of the original fitting instructions would be great. 

P.S. The Parvalux gearmotor in my original type of Rigel rotation system has packed in.  I've seen images of the Rigel system that came next, but still fitted the original type of 2.2m dome. It seems to have used a different motor, mounted vertically rather than the Parvalux with a 90 degree downwards gearbox output.  Any information on that other type of motor and how it was mounted would be much appreciated too.

I used to run to a schedule but I bought a device made by Inkbird that can switch devices such as a dehumidifier at a set humidity level.  It switches my dehumidifier off and on that way.  I periodically check to see what the dewpoint is expected to be and change the setting as necessary.  Seems to work OK as I don't really have any issues with humidity in my Pulsar 2.7m.

I used decking on mine with no insulation underneath.  It never feels cold underfoot; a completely different experience from concrete.

Steve

That is exactly the same Dome Controller Board as mine.  The main difference is that the first Pulsar domes had a different arrangement of the wall - dome interface meaning that the rotation system had to be battery powered rather than mains.  So mine has an internal 12V battery linked to a solar panel charger (I actually use a mains charger when the dome is out of use.) There are other threads in this forum that describe the process I went through to computer link (not using Shelyak) and the help that I got from others - which was essential. Mine is successfully computer controlled - for rotation only via a wifi connection.  The attached pdf file describes it and includes the parts and circuit diagram.

0819PulsarDomeAutomation.pdf

Steve

I have the even older style but I think the attached may be the instructions for yours (very basic in detail though).  I didn't know it used Velleman parts.  Mine doesn't but I've modified it to operate connected to the computer via a Velleman board.

ROTATION MOTOR DRIVE INSTALLATION NEW.pdf

My Pulsar dome sits on a stone circle rather than concrete (the pier base is concrete) so I didn't want too many holes drilled into it to support decking. The support framework for my floor has cross members to make it into a single, structure which sits atop the stone rather than screwed to it. Cabling goes under the floor with one section of decking hinged to give access if necessary. I have a gap of around 6 to 7mm between the decking boards for ventilation.  To avoid losing small items down those gaps I have a section of thin matting covering one part of the decking.  I've not suffered from condensation on the dome but do have a dehumidifier for the benefit of the telescope.

You won't find anything available off the shelf as each dome manufacturer tends to have their own bespoke system and none are cheap and cheerful.

If you search here you will find various solutions that have been produced DIY.  A lot of ingenuity has been shown and those who have come up with systems will be able to offer advice.

I was lucky to have the help of two Stargazerslounge users who helped me to automate one of the first models of Pulsar rotation systems, designed for the original dome version.  I had managed to buy that second hand.  Even that had to be modified a bit as it came from a 2.2m dome not the 2.7m version and it was really a clock work mechanism not designed for automation.  The newer domes are easier for rotation systems (including DIY) because Pulsar changed the design of the interface between the dome sides and walls.  That makes it easier to have a mains powered motor for rotation.  Mine is battery powered which is a significant limitation.

Well that has unleashed a lot of very interesting discussion.  I did have two PM that did offer good advice on the SXVR-H64 and as I did have a used one in mind I bought it.  Still waiting for a good clear night to properly test it.

I had decided on that sensor some time back because I wanted to switch to an anti-blooming sensor. I was attracted to the relatively high QE, the compatibility with my 1200mm refractor and with the ability to stick with 1.25" filters.  I'd been able to upgrade my set of those so I'm not ready to move to larger diameter ones.  There were a lot of good reports of the sensor too.  I was attracted by the good prices for 2nd hand 460EX cameras but my existing setup was long, making space a bit awkward in my observatory.  With the Atik it would have been even longer whereas the squat layout of the SX would save me space.

I was attracted by the built-in hub on the newer Trius models but views on that are mixed. My current thought is to mimic that using a 12V  powered separate hub which I think I could fit onto my filter wheel.

Service was another consideration.  I'd already been in contact with Terry and have found him very responsive and helpful.

In the future I may well switch to CMOS but for now I'm going to have a go with the SXVR-H64.  I may even try the spectrography, noting the comments on that.

Many thanks for all the comments.

This was what the company told me in an email 11 years ago: 

"the carrying capacity of UNI 14 is 55 kg and for UNI 4 60 kg.  The carrying capacity of UNI 14 at minimum height with 37 cm tray fitted is 59 kg and it's better to use the UNI 14 with minimum height as the UNI 4 with maximum height. The capacity could be increased by adding a 2nd set of clamps 2 kg."

So the tray helps a little bit too.

With Berlebach tripods the quoted maximum weight capacity is at the shortest height.  Leg clamps slightly increase the capacity.  So a pillar, as long as not too heavy is better than extending the legs.

I'm trying to decide whether to buy a new Starlight Express Trius SX694 Pro or a used SXVR H694.

Do the benefits, particularly of the re-chargeable Argon Filled imaging chamber but also the revised electronics and built-in hub (fewer cables), make it worth the extra cost? 

I'd be particularly interested to hear any comments on fogging/frosting during imaging with the SXVR-H694.

Many thanks

Thanks for that explanation.  I had surmised from Wim that it wasn't a good idea but you have filled in the detail.

I'll just use the filters separately, and as appropriate, use the NII as an additional channel.  Perhaps as some stage I'll make the change to 3nm Ha.

The reason is because rather than having two H alpha filters I have a H alpha 5nm and a NII 3nm.

The suggested method was what you wrote i.e. H alpha 3nm = H alpha and H alpha 5nm - H alpha 3nm = NII.

What I was asking about doing the reverse NII = NII (of course) but then H alpha 5nm - NII 3nm = H alpha.

Wim

Thanks for that.  A far from simple process to get it right.

Peter

SBig used to supply Custom Scientific (CS) filters as standard and the filters are still being made in America.  The are expensive too.

I know that they are not in common usage these days but does anyone have experience with the 4.5nm versions, especially the SII?

I've read posts suggesting subtracting H alpha 3nm from H alpha 5nm to separate the H Alpha and NII data.

I apologise if this a silly suggestion but in the absence of having both bandwidth H alpha filters would a viable option be to instead subtract 3nm NII from 5nm H alpha? 

My charger is a Yu-Power YPC2A12.  The old Pulsar Dome connection from Solar Panel to rotation motor unit is via a car-type connector but with an SAE type connection between the solar panel and the final connector.  I just disconnect that and connect the charger. I did find though that the polarity was reversed so I bought a cheap gender changer which sorted that out.

I don't suffer from condensation so I think that the space at the dome/walls junction allows enough ventilation.  Not sure if it makes any difference but my floor is raised too, with gaps between the decking boards.

I have a solar panel for my rotation battery (again its the old style dome) and even fitted a bigger one than Pulsar provided but with us often not getting a lot of sunlight in the winter I connect up a mains charger when I close down.  As it's designed to also trickle charge I most often just leave it connected all the time.

Looks really good.  I took my locally made steel pier to a powder coater (does wheels etc.) and that has stayed rust free for years.

Just looked at mine and it has a flat rubber strip effectively filling the gap that can be seen on yours.  The original Pulsar instructions show it, see the bottom left image on the second page of the attached.

2.7M OBSERVATORY INSTALLATION.pdf

My Pulsar is one of the original models, just with a rope and pulley but I've certainly never had any rain get in at the top of the shutter. I will have a look before it gets dark.

With your shutter being powered I would have expected that the microswitches would make it stop in the same position (open or shut) every time. I presume that you did not re-position them and that they are as the previous owner had them. You could perhaps ask the previous owner if he had any such issue.  Another option would be to ask Pulsar.

When I planned the electrics for my dome 11 years ago I decided, as a precaution, to house all double sockets in IP66 boxes and similarly for dimmer switches, timer socket for the dehumidifier, fixed power supplies for the mount, my main imager and other ac to dc adapters.  I boxed in the pier with plywood, with a gap to prevent vibrations. That produced four wooden surfaces to screw components to.  The cabling from the house all comes to the pier initially but then power, usb and networking cables all go under the decking floor to a desk area.  I didn't want to alter the dome itself so I sandwiched one of the section joints with uprights and screwed plywood to that. White and Red lights, a 12V supply and more power points are attached to that, located under the fixed desk.  One decking board is double hinged so that it can be lifted up, crane like, to access the cables.

I've had no shortage of electric points.  Now I have a monitor on an arm fixed to more wood, this time sandwiching the joint above the desk.  It can rotate the monitor flat against the dome wall or move it out for convenience.  The lamp shown in the picture is now mounted on that wood.  The computer is in the house, under the stairs, with another screen , keyboard and mouse - that's the 'warm room'.

The only thing I would have done differently would have been to have a larger diameter pipe for pulling more cables though e.g. usb3.  I do have a wire to pull more through but not sure it wouldn't snag.  The dome rotation is powered now but by 12V battery.  After use it is recharged from the mains, although there is an external solar panel for recharging too.

My understanding was that there were vibrational advantages to having a heavier weight closer than a lighter weight further out.