teoria_del_big_bang

Are both power supplies the same and are both a smooth 12V?

If both are the same I would make it easy and supply the mount with one supply and then use the other for everything on the mount, that way the cable runs are simple  - one to mount and one to the rig itself. Although if you add everything up on the mount it is just slightly over 6A (even with 2nd 4W dew band) this is an absolute maximum and I would be surprised if the mount takes anywhere near 4A, if its a very big mount then I guess it may do when slewing but surely not when tracking (I have no idea what mount it is so only making an assumption here) and the focuser is not going to be taking 2A when at rest and again this seems quite high for a focuser so I am thinking this is a big rig ?.

Is 17W at 50% 2x  the same as 17W - Didn't quite understand the question - are you saying you have two 17W dew bands but running with the controller set at 50% ?

I see no reason why dew band would be noisy unless there was a bad connection that was arcing or kept momentarily going open circuit. They essentially have no components in them to create any electrical noise as they are just some for of  resistance in the form of a series of resistors or some nichrome wire. But some forms of controller to regulate the temperature could cause a small amount of noise depending how they are controlling the voltage but I doubt this is anything significant to worry about. 

Not sure just what camera you have so not sure what the 12V is used for but i suspect only the cooling circuit and the camera itself will work taking power from the USB so a very clean 12v supply not strictly necessary, I just like to not run the USB back via a hub is at all possible and have a dedicated good quality USB lead directly back to the computer.

Is the US hub powered ? 

Steve

37 minutes ago, Kev25 said:

Hi,. Hope you don't mind me cutting in on this topic.  I too am a complete beginner in astronomy, and looking for a first telescope, after reading the posts in this topic I think the 130p flexitube would be a good start.  My question is, would I gain much by going for the Skywatcher 150p flexitube over the 130p ?.

Thanks

Hi,

This is quite an old thread but there will be plenty of members very happy to help you with some great advice.

You may get better information if you start a new thread in this same section and maybe introduce yourself and explain what you are hoping to do with your scope. Do you want to just use it from your back yard, or do you want to travel to some dark sites, are you just interested in visual or are you wanting at some stage maybe to do some photography and so on.

Steve

Oh not nice at all. Thats why we like spiders in this house.

Steve

11 minutes ago, fozzybear said:

Steve you beat me to it was going to offer the same

Ha Ha , not often I beat anyone these days 🙂 

Steve

https://www.amazon.co.uk/Buwico-Converter-Supply-Module-Non-isolated/dp/B00ASJX5C8

Steve

John,

That's what I would do. If you do not move too far from the car so weight not a big issue you can either but the 17Ah battery and leave a space to add a second one if you need more power or probably will get a bigger battery for £50 or so.  It/s not easy to say how long things will run reliably run on these batteries as i am sure you know although it states 17Ah you will not get a full 17 hours at 1 amp from them. Also whether your mount will give any funnies at 12v or below really needs checking, my HEQ5 seemed fine at even 11.5v but the manual says not to go below 12v and I have read threads about steppers missing pulses at low voltages.

Steve

Just now, Jm1973 said:

Thanks for the reply.

I used to build and fly drones so I am used to the drill with charging/discharging/recharing etc.

I will only be using this when I travel to dark sites etc. Which realistically won't be that often.

I generally image from home, and I use an extension lead in a box, going back to the house and plugged into an RCD then.

 

Very much like myself then.

If you fly and maintain drones I suspect you would have little issues with buying a 17A/H  battery  and making a nice box with all the required connectors.

Personally, I think it would work fine for the small current you are drawing (probably no more than 1a most of time). If you are using Dew bands though this may add around another 1a to the draw.

In my ey experience I have used them for my mount in the past and also used to use them when overnight carp fishing to run lights and a 12v television so worked on low currents.

Steve

Personally, I would sort of agree with both replies, which may sound odd as they are quite different.

In short:

• I suspect the jumpstarter will in effect be no real different to the skywatcher lead acid option.
• From my experience with them they will power a small mount and camera for a reasonable time , probably for at least 4 to 6 hours reliably - but all depends on whether it is just the mount and camera and how often you are slewing at fast rate which takes a lot more current, and that you are not also using dew bands and other bits on the 12V.
• I suspect it will last a number of years so long as you maintain its charge and when you have finished a session you put it on trickle charge till fully charged and when left in storage you take it out and trickle chage to fully charged every few weeks. But that will be no different with the Skywatcher version.
• A far better, but more expensive, option is something like Celestron Power Tank

Inside the starter will be a small lead acid battery similar to 17AH Battery and in my opinion is fine for powering a mount and I have used similar in the past with no issues.

I cannot tell for sure , without buying one and looking inside, but as it is a relatively cheap so called "Jump Starter" if it like the ones from Halfords I have had in the past it will not have a specialized high current battery inside but one very like the link which are still capable of high currents so will start most car engines if it is fully charged but do not tend to last too long if used a lot. But they seem to work fine as well delivering 1 to 2 A as you will require, so long as they are looked after properly and charged properly. 

To be honest although again I do not know I always assumed the Skywatcher Power Tanks  (which are now £99 from FLO Skywatcher Power Tank 17aH ) were just the same as the Jump Starters and would have the same batteries. But I could be wrong and would be nice to know from any owners that have had them apart if the batteries inside are any different.

BUT, as @Waldemar does say it is not ideal for several reasons .

Whatever, both the Jumpstarter and the Skywatcher are lead acid and do suffer from lowering in voltage as they discharge and will start off at 13.8 V  and will quickly drop to around 12 to 12.5 v and eventually will be a little below 12V as they approach being discharged. Again when I used these I never had issues either with mount or camera when even a little below 12V but I have read threads where people do have issues with the mount when slewing at 12v or below.

Also they need looking after in that they do not like being fully discharged and if left discharged for any length of time you will lose a lot of its potential and will not really be capable of providing 17AH anymore and if left a long while will become almost useless. They will also discharge themselves to some extent even when left in storage not being used so if you need to use it and have not used it for a month or so you may need to do a bit of a charge before using it if you want it's full potential.

A far better option is a  LiFePO4 battery, but you will pay more than £50  for something around 17Ah, but ultimately might save money as they will last many years longer and will be easier to look after (and they are a lot lighter if you are traveling with them.

Also I do agree with @Waldemar about the cigarette lighter connectors, totally useless and give too many problems with bad connections for astro use but so much equipment uses them.

Where are you wanting to use your scope ? Is it just from home or are you traveling to remote sites ?

If just from home why not use something like this Outdoor 12V supply Ideally housed in a waterproof housing that is large enough to stop supply over heating and also then connected via a Rcd unit.

Steve

Someone with more experience will probably be able to answer better than myself but from my understanding basically it is because the flat images will change slightly over a fairly short period of time even if the camera orientation does not change.

With flats you are trying to remove things like dist bunnies, general blemishes on optical surfaces.

As you can imagine dust and blemishes will accumulate over time and so what is in the optical path one day will be different several days, or maybe weeks later.

I believe some do use the same flats for several weeks or months and to a large extent they probably work fine until there is a significant change in the build up of dust and other blemishes, so if time is short and you cannot get the time to take more flats then using a recent set would be acceptable, so long as something has not been removed and rotated such as camera or filters. But obviously if you are able to take flats at in the same session then that is ultimately the best option.

Bias again will change with time and temperature so as long as they are taken all at same temperature as the lights and other calibration frames and are recent then using the same bias frames would be acceptable but as they take such a short time to obtain it is not a bad idea to take a new set at least every few months.

That's my understanding anyway, as I say somebody I am sure will have a better insight into the whys and wherefores and you will find many do use a library of these short term, whilst others will always use new frames, I am sure.

Steve

I currently have a pretty robust setup that I am 95% happy with, and the main downside I am not happy with is that I cannot easily rotate the camera to change the FOV angle.

In theory on my Esprit Pro I can loosen the locking ring and adjust the angle but really I do not count this as a practical option.

Ideally if money was no object and I could fit one in without affecting the optical train I would love one with a motor that I can operate remotely but I do not think this is necessary as it is just something I need to do once in the night at start of a session so no big deal to do this manually.

• Is there a preferred rotator for this sort of setup that is particularly better than the rest ?
• Where ideally is it placed in the optical train ?
  • Ideally for me would be between the FW and camera but then it is not ideal to have this distance any further than necessary.
  • If placed before the FW then I have a fairly big FW rotating as well which may mean it can hit the mount legs if in certain positions.
• Can they introduce other issues such as tilt ?

Steve

Hi CMR, welcome to SGL 🙂 

Well you certainly have done the best thing you can joining SGL both from the Astro side and online community side as well.

Not too long ago, about 3 years,  I was completely new to the hobby but with loads of help from many SGL members I have gone from knowing nothing to at least enough to be able to take reasonable images of DSO's . Also, I had used other online forums for some of my other hobbies so was not new to me I have found SGL the friendliest forum I have used by a country mile, so feel free to ask any (ANY) questions you need, you will never be belittled for asking even what seems to you a silly question.

Best advice I am able to give you is to ask lots of advice, do not rush into buying a scope or setup because you see what seems like a great offer on some obscure website or on the well known auction sites, it is very easy to buy lots of what seems like a bargain to you at the time and end up buying again because it is poor quality or just the wrong setup.

Although I am into imaging now my first buy was a very manual Dobsnian bought 2nd hand for not much over £100 from another SGL member. It was a great introduction to Astronomy and still have it as it offers some great views and so easy to use.

Anyway enough for now enjoy this great hobby Obsession 🙂 

Steve 

Yes I agree on both counts, great avatar and a fantastic image. 🙂 

Steve

I must admit when I left school at 16 I did well in the sciences and understood everything up to O level standard as it was in the 70's. (but then what did our teachers know - atoms were made of 3 particles ha ha) . But some of the new stuff is well beyond me and it always seemed that when a bit of a theory did not fit the real world then an unknown variable was added to make it work and left for someone to find that variable at a later date. Forgive my simplistic view I just aren't that clued up but from my simple view of the universe that's how it seems.

Steve

I found my original email to Rogelioi.

Rogelio,

We already have a thread going on Stargazers Lounge  which is the biggest astro forum in UK. So far comments are more than favorable.
One think we discussed was maybe some way of importing several copies of the book at same time to reduce the postage cost to each recipient.
We are also not sure if we would be hit with import duties as well as the postage.
The cost of the printed book is very fair considering the time and effort that has gone into it but I am sure you are aware the postage add a significant extra cost and if we get import duty on top then it is more than significant.
We were hoping maybe FLO could do the importing in bulk therefore keeping the extra costs reasonable, I do not know if you yourself have considered a UK or European distributor ?

And the reply:

I did email the author and suggest he try to get somebody to import them in bulk, I think I suggested FLO as well, I can't quite remember what was said but I think it was that individual books could be imported without duty but a shop importing several would have to pay duty and the final cost would not be that much less. If I can find the email he sent I will add it to the thread.

@kirkster501 is absolutely right and I always find many of us think very similar when it comes to things like books and especially software. We are quite happy (or fairly okay with it anyway) to spend £1,000'S on gear such as scopes, filters, mounts etc but hate spending over say £40 for a book or say £100 for software. And I include myself in that to an extent. But both these are essential I think for AP and to be fair the work that goes into producing these is also no mean task and deserving of a fair return. 

As I say I to have the same sort of feelings, I am not made of money, but have bought this book and also paid out for the PixInsight software so no small outlay but now I have them I really feel the cost was justified and very happy to own them

Steve

26 minutes ago, reezeh said:

And spend the rest of the night going to the loo 😀

Ah well yes there is that, but at my time of life that seems to be the case whether I have had anything to drink or not and whether I go to bed or not. 🙂 

Steve

Always good to buy from a SGL member and I would think it will have been well looked after so might have had bearings replaced.

Regarding how much pre-load on the taper bearings then follow this procedure.

heq5-rebuild

You can imagine as you tighten the nut up that holds the bearing in place as you tighten it up you are squashing the two halves of the bearing together and as they are tapered, like wedges they start to wedge together.  All we are after is that there is no play in the direction you are winding the tightening nut (sorry for bad explanation not my best attribute). We do not want it any tighter than that as the more you tighten the more force needed to turn the two halves and unfortunately the stepper motors are quire easily stalled when doing fast moves so too much force required will cause them to stall.

Steve

8 minutes ago, matt_baker said:

Do the tapered bearings have much impact on performance?

They do but unless they are damaged or not tightened correctly they are unlikely to have worn.

Was the mount new when you bought it ? If not then like me unless you ask and the mount has not had previous owners befor who you bought it from then you do not know what they did to it.

Steve 

I would agree with your suggested course of action in your last post.

I would suggest to remove all traces of old grease and especially if the grease in them looks in anyway contaminated.

When cleaned before replacing them in the mount just rotate them by hand, they just need to be smooth and not notchy in any way. If they are then the will need replacing.

Do not be tempted to pack them tight with grease worse thing you can do apart from leaving them dry. Just lightly pack them. 

Steve

If you are not wanting to spend too much I would look at them first and see if they need replacing. I bought my HEQ5 2nd hand and I do not know whether the previous owner had already replaced them but in my opinion when I striped it all down it did not need any replacing, maybe the smaller bearings on the worm gear shafts, but others were fine.

I had already bought them so replaced them anyway. But, I cannot say whether they were the original ones or not as they were already good quality bearings in there.

In general these bearings are not doing any amount of work, they are not moving at 1000's rpm and have very little load on them. I think what matters is they have not been running without some lubrication at any stage and they are not over packed with thick grease. On top of that it is more the adjustments to remove any backlash both in the taper bearings and in the mesh between the worm and the worm gear.

But some gentle adjusting and most of all patience is required to get the best out of your mount.

Whilst a very good mount for the price in my opinion (and I am an engineer although semi-retired now 🙂 )  it is not exactly a piece of precise engineering so unless you are very lucky and have a perfect one I suspect you will not get rid of all backlash. I also suspect they vary from mount to mount and some will be slightly better than others but all should be fine.

The taper bearings need to be tightened just enough to take up any play but no more, from what I remember it is not much more than hand tight. If you start to put any amount of pre-;load on them then the stepper motors can stall during a fast slew to target.

On top of that there is a bit of very fine adjustment required to get the least backlash out of the worm and worm gears. If like mine they will be a bit cyclic and at some point in one rev of the gear it will have a bit more backlash than at 180 degrees different and so you can only fully remove the backlash at the tightest point and there will be minimal backlash 180 degrees away from that but there will be some. If you try to remove backlash from the tight spot then again it will bind when doing any fast slew and may show up in the guide logs.

It took me quite a few attempts to get this nominal and required some very small adjustment moving the adjustment screws just a few degrees, no moving 1/4 turn or even 1/8 turn.  

Steve

How long do you need the entire USB3?

Personally USB2 or USB3 cables were the bane of my life for over a year. When I used extensions of any length (10M) then sometime they would work and others just nothing but problems.

I would certainly go with good quality cables and cannot recommend  LINDY enough especially their Cromo line.

But I still had issues even with good quality USB3 powered hub still had intermittent issues.

I did  asked many questions on SGL and the house was sort of split down the middle with some having great success with long USB cables and others saying don't bother as they will be trouble. So I was really confused to understand why some could get them to work well and others couldn't. 

I did have success with USB to Ethernet for distances over 20M. and now for over a year now I use a remote computer of some sort at the mount and keep USB cables to 2M or less then use remote desktop or similar to communicate from afar.

I hope you have better luck than I did.

Steve

Hi Alan,

I would be more than happy with that, lots of detail in that and some great colours.

But after saying that some people just seem to be able to pull rabbits out of hats and make any data seem so much better.

Steve

4 minutes ago, Paz said:

Well done on making some progress on your garage. I've been meaning to sort out the tip in my garage, that was 10 years ago and it's still a tip.

Totally with you there, I keep getting mine tidy but I am such a messy worker and usually leave no time to tidy up it soon reverts back to a mess very quickly.

Steve

I have not used this yet but you can view your Guidelogs with this tool:

PHD LogViewer

Steve

What mount ?

Almost looks like something sticking then after a lot of correction pulses it moves with a jerk and over corrects getting worse every time it happens.

I am no expert but plenty on here very good with PHD2 but probably will need more info such as some Guidelogs and how you are guiding (i.e. ST4 or ASCOM/INDI).

Steve