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Astrokev's ROR - The Build


Astrokev
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5 minutes ago, Astrokev said:

Arghh!

Why do you suggest this Ray? I presume it's not just for extra space, so guessing it's due to possible interference?

To be honest I was anticipating having the laptop next to the scope since getting the thing focussed with the lappie in the warm room would be tiresome. But then I saw Lee's idea of having a second screen next to the scope....

Yes just purely this, Kev.  

Ideally you want to restrict the length of parallel run with data and power in close proximity.  For your mount you will naturally have some up to the OTA which is pretty well unavoidable, but limiting it elsewhere is advisable if possible.  Don't think I'm saying you should as naturally it may well be absolutely fine, it is purely a suggestion whilst it is still pretty easy to do.

Screen next to the mount is ideal. I have a monitor on the wall next to my mount in the scope room and it comes in really handy :thumbright:

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1 hour ago, Astrokev said:

idea of having a second screen next to the scope....

Exact same reason for me Kev, all I needed then was to run a HDMI to the pier instead. I got 2xUSB3 facias and 1 HDMI with room for another as I'm not sure myself what else I need yet. I only ran these media cables through my conduet though as I supplied the pier separately with it's own twin socket.

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Edited by Guest
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2 hours ago, Astrokev said:

To be honest I was anticipating having the laptop next to the scope since getting the thing focussed with the lappie in the warm room would be tiresome. But then I saw Lee's idea of having a second screen next to the scope....

Awesome build thread, really enjoying it. 

After spending so much time and money on your build you deserve to splash out a couple of hundred more on a decent Ascom stepper focus controller. 

What's manual focusing? ?

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2 hours ago, RayD said:

Yes just purely this, Kev.  

Ideally you want to restrict the length of parallel run with data and power in close proximity.  Don't think I'm saying you should as naturally it may well be absolutely fine, it is purely a suggestion whilst it is still pretty easy to do  

I'm very much a novice when it comes to imaging and electrics/tronics ?but please could you explain what problem may result in running them in the same conduit? Trying to drag out school boy physics from the back of my mind. Probably get this wrong - could the power cable induce a current in the data cables which could interfere with the signal?  

I'm sure I could do something if this is needed, I'd just have to run a separate cable up the side of the pier instead of inside the pier as currently. 

Cheers

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2 hours ago, LeeRich said:

I only ran these media cables through my conduet though as I supplied the pier separately with it's own twin socket.

Thanks Lee. What route does the power cable take? As far as I can see it's still in the pier along with the data cables?

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50 minutes ago, Starflyer said:

Awesome build thread, really enjoying it. 

After spending so much time and money on your build you deserve to splash out a couple of hundred more on a decent Ascom stepper focus controller. 

What's manual focusing? ?

Thanks Starflyer, that's nice of you to say. 

Yes, something to consider, but I've already splashed out on 2 new scopes and some eyepieces! Maybe I should add it to my Christmas list ?

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14 minutes ago, Astrokev said:

Thanks Lee. What route does the power cable take? As far as I can see it's still in the pier along with the data cables?

There is a spur off the ringmain under the floor that runs up inside the pier and feeds the double socket, all the ancillary cables run in a 40mm waste pipe that is attached to the outside of the pier and feeds into a double back box that then has the faceplate connections in. ? I doubt I will have any interference as the pier is 6mm thick and the cables are in plastic pipe and are separated by about 4" from the 240v feed, i tested it all the other night with my laptop as I'm still in mid build with the pc but the pic attached is a live video and it all worked a treat.

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33 minutes ago, LeeRich said:

There is a spur off the ringmain under the floor that runs up inside the pier and feeds the double socket, all the ancillary cables run in a 40mm waste pipe that is attached to the outside of the pier and feeds into a double back box that then has the faceplate connections in. 

 

Ah, I didn't notice the external conduit ??

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With cat5 at least, there shouldn't really be any interference problems I think.  If I recall correctly (and I admit it's a very long time since I did this stuff) the signal level is determined by the difference between each of the pairs in the cable that are twisted around each other.  In theory at least, any induced interference in one core of the twisted pair should be pretty much the same as in the other, so the difference will remain the same, or sufficiently the same that the signal is not degraded beyond recovery.

I'd certainly not argue against running power and data separately if it's convenient to do so, but I'd not panic about it otherwise.  If I were that worried then I might be tempted to use a shielded cable for the cat5 link instead of unshielded.

I don't know about other data cables such as HDMI though.  I imagine you can get shielded versions of those if necessary.

James

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Thanks James. 

So, to paraphrase what I think you're saying, any risk of interference can be mitigated with shielded USB and HDMI cable?

For interest, with unshielded cables, how close do data and power cables need to be to be a risk?

I may run a separate conduit to the pier for power as Ray suggested, but leave the outlet just below a separate panel in the floor in case I need it. It would then be fairly simple to lift the panel and extend the conduit up the side of the pier. 

EDIT - another question has just occurred to me. Is inter-cable interference a risk with cables of all voltages? To reduce electrical hazard at the pier, I may run reduced voltage from the warm room to the pier to power the NEQ6.  Would this present the same risk?

Edited by Astrokev
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The main problem probably wouldn't manifest on Cat5 cables due to their construction, but USB ones are the likely problem point.  You will be at the upper length limit of USB2 cables, so any interference will be accentuated and can easily result in dropped frames etc.

As noted, it may well never be a problem, but I'd hate for you to do all this hard work to end up with problems when the additional conduit (it doesn't have to be a big one) will make sure you not only have capacity, but also as good as you can realistically get with separation.

230V mains and 5v is not a good combination for parallel runs.  There can be issues, but it would normally be over longer distances than this.  The problem isn't really about how close, as the cables can cross at right angles quite happily, it is about how long they are in close proximity for (parallel runs).  13.8v and 5v won't be an issue as far as voltages go.

It is a bit belt and braces to separate them for a run of this length, but then so is your whole build.

Your warm room is pretty close to your pier so you could happily run 12v (13.8 ideally) which is exactly what I do.  I have 2 power supplies in the warm room, one for the mount and the other for the rest, so only have 13.8v at the pier.

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Even on USB, I wouldn't expect much cross talk, as all good leads will have earth screening. The worst possible signal crosstalk would be from the square wave pulses, that drive the focus motors, & come to think about it, the same similar pulses driving the mount itself.

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There you go, it will all be fine then.

My view has always been that of the IET (of which I am a member) which is where power and data (LV and ELV) is combined in a trunking or conduit, the run should be less than 1m and, if unavoidable,  all cables should be rated at the highest circuit value.  This is in case there is a short circuit situation causing the higher current to travel down the smaller cable, not to do with cross talk.  However, even with the best cables I suspect the likelihood of, or potential for, interference is increased also.

As I said, Kev, it may well be fine from an operational perspective, and as far as obsy's go it is belt and braces, but using one conduit (a plastic drainpipe is a conduit) for power and data without physical segregation really isn't the right way of doing it as far as the wiring regulations go, but it's your build so you do it how you feel is right.

Really looking forward to seeing it progress and working in time for winter, which I'm sure you are also.

Edited by RayD
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Thanks to all who've shared their knowledge on this point. I certainly feel like I've learned something, which is great. 

Pulling it all together, the best way forward is clearly to put in a separate conduit for power. Even if theory and practice do not fully agree, it's a sensible contingency which could save lots of headaches and extra work down the road.

One thing it's becoming clear that I need to do is decide how I want to wire up the building. I want to keep 240V out of the scope room, which seems sensible on safety grounds. Beyond that I haven't given it much thought. My approach was to complete the build apart from wall coverings, then install wiring before I put the panels up. I think that still works but it's something I need to start thinking about. 

Thanks again. You guys are great!

Right, it's raining, limiting more work on the never-ending door project. So, think I'll head down to the plumbers merchants ?

Edited by Astrokev
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17 minutes ago, Astrokev said:

Thanks to all who've shared their knowledge on this point. I certainly feel like I've learned something, which is great. 

Pulling it all together, the best way forward is clearly to put in a separate conduit for power. Even if theory and practice do not fully agree, it's a sensible contingency which could save lots of headaches and extra work down the road.

One thing it's becoming clear that I need to do is decide how I want to wire up the building. I want to keep 240V out of the scope room, which seems sensible on safety grounds. Beyond that I haven't given it much thought. My approach was to complete the build apart from wall coverings, then install wiring before I put the panels up. I think that still works but it's something I need to start thinking about. 

Thanks again. You guys are great!

230v in the scope room is fine, Kev, so long as it is RCD protected.  My preference, just a personal one, is to not have 230v at the pier as there is no need for it, and invariably it will mean you just need to add a power supply at that point in any case. 

I have mine wired on 2 x 20A radials, one for the warm room and one for the scope room.  This means if there is an issue in the scope room it isn't going to take out all the power to the computer etc.  My scope room radial is used for dehumidifier, USB camera and second monitor supply.  It also gives me a couple of sockets for small power tools and my little electric blower etc.

I'm not saying there is a right and a wrong as everyone has an opinion, but to put another conduit under at this stage is pretty easy, to do it later if you need to (accepting you may not) is going to be a bit more problematic.

Edited by RayD
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1 hour ago, Bizibilder said:

If you do wire up before cladding the walls draw a diagram and take some pictures as well - It's easy to forget where the wires are should you need to drill a hole later!! ?

Spoken from experience Roger?

Certainly I have done such things myself,
worse many years ago completed a new pipe run and then fixed into it the next morning!

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5 hours ago, Bizibilder said:

If you do wire up before cladding the walls draw a diagram and take some pictures as well - It's easy to forget where the wires are should you need to drill a hole later!! ?

Thanks Roger. I was going to do that coz it just seems the sensible thing to do for the reasons you state. But thanks for the reminder ?

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5 hours ago, RayD said:

230v in the scope room is fine, Kev, so long as it is RCD protected.  My preference, just a personal one, is to not have 230v at the pier as there is no need for it, and invariably it will mean you just need to add a power supply at that point in any case. 

I have mine wired on 2 x 20A radials, one for the warm room and one for the scope room.  This means if there is an issue in the scope room it isn't going to take out all the power to the computer etc.  My scope room radial is used for dehumidifier, USB camera and second monitor supply.  It also gives me a couple of sockets for small power tools and my little electric blower etc.

I'm not saying there is a right and a wrong as everyone has an opinion, but to put another conduit under at this stage is pretty easy, to do it later if you need to (accepting you may not) is going to be a bit more problematic.

Thanks Ray. Useful advice and suggestions there ? 

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So, unsurprisingly, here's today's progress ?

Following the helpful discussion and suggestions, I feel a lot happier now! I just need to screw the pier end to the pier but there's no urgency on this.

In addition to the second conduit, I also sanded the door and re-hung it to check I'd trimmed enough off the bottom, and that there were no other surprises lurking. All seemed fine so off it came again and I painted the bottom edge, which will be fiddly to do once it's hung. Weather permitting, it'll go up tomorrow, and hopefully stay up! I'll finish the painting in-situ.

Didn't post a picture of the mesh yesterday, so added this to the pics. Not rocket science, but makes a refreshing change from plastic pipes and doors ?. Will eventually put stones over the bottom to make sure it forms a good seal.

 

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