fifeskies

Cheap and cheerful external HDD as an archive is what I do. Connect it once in a while to offload data I no longer work with but "may" just want to come back to. Doesn't need to be a fast high performance (read expensive) drive , just data dump overnight.

I have an electrical engineering background, so apologies for becoming a bit technical. And don't be too worried about what follows , your installation has clearly been working well without problems for some time. Its just a "for info" comment. (and not having seen your installation I am making a few assumptions). You have turned your observatory into what is termed a "TT" installation by using the local earth rod if it is connected into the incoming supply. This now makes your observatory earth point and your source earth point at your consumer unit at a very slight changed potentials. While in all probability all should be fine with this I would still be tempted to install a local 2 pole RCD/interrupter at the observatory end. The disconnect time can be affected by relying on the source protection at a far origin when you "TT" your installation. A local protective device will ensure you get the fast disconnect at 30mA fault you need. If just the pier is earthed and not the incoming supply you have an "exported TN-S" type supply and the source protection should probably be adequate, a local RCD will not cause any problems, but may be superfluous. Exported TN-S does have cable resistance limits to function correctly , a long cable that is not of adequate thickness (cross section) will mean circuit protection can fail to operate as expected. In the UK exported TN-S is actively discouraged for this reason. However with exported TN-S you need to ensure any mains equipment of type 1 , ie with an earth connection , does not come into contact with the "TT" earthed pier as this then reverts the electrical installation to a "TT" type. https://uk.rs-online.com/web/p/rcd-plugs/7508450/ https://uk.rs-online.com/web/p/rcds/0490157/ My own observatory has a TT installation with its own earth rod and I have used a local RCD in the observatory to ensure maximum safety. Note: 1 Most computer screens running on mains are type 2 (no earth) so dont cause problems when you mount to a pier 2 All the equipment run on 12 v from your supply will be isolated from the mains so should not cause any issues on the earthed pier. However the ground (-V) line on the supply is connected to earth via a capacitor to help avoid it floating too far away from local ground potential and supress ripple noise. So try to avoid the 12v supply touching the pier.

You will be protected at source and all your power should be safe as long as your property meets Danish standards Since the early 1990s earthed sockets have been required in all new electric installations in Denmark. Older sockets need not be earthed, but all sockets, including old installations, must be protected by earth-fault interrupters (HFI or HPFI in Danish) by 1 July 2008. Earth fault interrupters are essentially the same as RCD in that they disconnect inbalance faults caused by a person touching a live wire.

Supply the PSU via an RCD to be sure you stay safe. All my mains in my observatory is supplied via a 30mA 2 pole RCD in the small local consumer unit powering my sockets.

Thats the 200w version. OP has the next one down , the 150w version. Looks like 200w has autosense but the 150w is manual set

https://electronics.stackexchange.com/questions/183695/rs-150-12-ac-input-switch

Its possibly a small slide switch on the PCB though there is a chance its a pin header you lift up and move across

will not survive 230 if set for 120 I suspect see diagram for switch

These are usually dual voltage "88 ~ 132VAC / 176 ~ 264VAC selected by switch 248 ~ 373VDC(Withstand 300VAC surge for 5sec. Without damage)" there is probably an internal switch to set either nominal 120 or nominal 230

Yes I wanted to be sure my dew heaters were on so added the LED monitor, cant just trust they are on and end up ruining lots of exposure time. My controller sits under the owl cage plate so I can see the faint reassuring red glow. 🥵 solar isn't something I have tried (yet) , but it suffers just the same from clouds I expect 💭💭💭

Most resettable fuses have a trip factor of 2 so again try to choose a slightly lower fuse rating if you used resettable fuses. Most cartridge fuses trip at 1.5x factor ie a 5 amp cartridge will break at 7.5 amps , a 5 amp resettable will trip at 10amp , in this case use a 4 amp resettable to trip at 8 amps. resettable types are best for protecting more robust items , ideal for dew heaters , less so for mounts where I would prefer a fuse. Fuses will trip much faster on a very high fault.

Blade fuses (car fuses) tend to be slow acting, but good enough if you choose a slightly lower value than you would for a cartridge fuse, not twice running current for certain. I avoided too many LED monitored fuses as they add to light pollution for night imaging , but have my dew heater outputs on LED so I can see how high they are turned up. Have been reducing my treeline with a reciprocating saw to reduce height a bit but have neighbouring trees I can't avoid out to the East.

The custom horizon is very useful and not that difficult to set up, there's a guide online for doing it. I too had a similar tree in the way , I improved my custom horizon with the aid of a reciprocating saw (much easier to handle than a chainsaw). 😜

The alloy plate will be needed as a heatsink I suspect. Tidy now as just had a big clear out ready for the winter You can never get away from the wires tho, my baby rig has them running in all directions. (Its easier to be tidy when I have my bigger scopes on the pier)

I'm about 30 mins from Rosyth. Not that I have any call to go there. For a while they ran the Rosyth to Zeebrugge car ferry and I took it once on holiday. Shame its gone as it made Europe a lazy sail away overnight for us. Been to Denmark but as a touring student many many years ago. I have a warm room for imaging so dont need to be at the scopes except when I'm enjoying some actual visual views , which I will always do. Always happy to help out anytime.

For dew straps , they should never draw significantly over the nominal current. So I use 2 amp fuses for my 4 inch dew straps rated at 8 watt (0.7amp) , but could actually probably use 1 amp. My heaters work through a control box with 2 channels and 1 fuse each output at 2 amps , the contol box input cable has a 5a fuse I have a 5 amp inline fuse for my NEQ6 to allow for a surge if both RA and DEC motors start together, and that seems fine , tracking the current is far below that. 1.5 times to 2x the nominal steady current is usually about right , though anything very sensitive to overload might need closer tolerance. I have LED strip lighting in my observatory on 12v , that only needs a fuse slightly above the load rating as it is usually dimmed well down. So for a 4 amp length of LED strip (when on full) 5a can protect the circuit. Photo shows Moon and Venus from the observatory with the LED lights on full for the photograph (usually dim red).

Stepper motors will be managed by the driver circuitry and stall current may well be limited by the controller, They will probably try a bigger current if they detect the motor not turning but not overdrive it (assuming a decent design). The drive transistors may well fail before there is any motor risk as the boards tend to have small electronics that are less robust than the actual motors. I would still go for an inline supply fuse myself just to be sure. My inline box and fuse cost me only about £2 or £3, a lot cheaper than swapping out a damaged motor or driver board. This is the one inline with my NEQ6 mount, fuse is near to the mount end for easy access , though it has not needed replaced so far.

While short circuit protected , you might still want to consider in-line fuses to protect your astro gear, especially drive motors. If they stall they will draw damaging high currents and without any in-line fuse this supply will continue to deliver the high current to the motors. A small fuse panel with individual protected outputs is easily added I have small inline boxes on all my cables with a fuse protecting the line. Use anti surge fuses to avoid surge nuisance problems. (my supply can deliver up to 50amps into a stalled motor so very much needed in my case)

Looks to be a good match , a switch mode of course but nothing wrong with that ( I am old school and prefer the linear type ). Will need put into some sort of external ventilated box to protect it from damp. My only concern on these is the convection cooling aspect , my supplies above 100watt are all fan cooled, usually with a thermal switched or controlled fan that only runs when needed. I would add a 12v fan run from the output to blow cool air over it, fit this inside the external box and it will stop it overheating. You will be able to trim the output voltage a bit if you want to. Use nice thick hook up cables and you will be fine , I use 2 x 0.75mm cables most of the time , these are nominal 6 amp rated , but still small enough to fit the common connectors.

The standby current of a big linear PSU is well below its output rating, once the initial current pulse charges the (usual) big output stabilising capacitors. In use apart from a slight thermal loss , you will only be paying for the power you actually use, and this is liable to be similar to the losses in a bunch of powerbrick individual units , and perhaps actually less. My big beefy bench PSU does not get very warm in use , I am sure if I was drawing anything like its output rating it would get fairly warm but I am only using a small percentage of that on average.

A decent battery and charging solution will work very well and give a stable supply. With mains in my observatory I decided the big bench power supply was the easier solution as I don't have to consider battery health. My supply is well above the rating of any use I will put it to and can just add 12v gear without having to consider the current draw issue. (It can supply 25amps continuous). One slight advantage of the big battery route (well 2 actually) , it can be used as a portable supply away from the mains (and 2nd it keeps the gear running during power outages). I don't use my main rig away from the observatory so didn't need portability.

Seems very short sighted to not use stainless screws and bolts , I swap out any I can get to easily for SS versions and I keep my gear in a ROR. They still get damp on dewey nights with the roof open. Inside the mounts is not such an issue as they will be warm inside when running and so should remain drier, and for me at least when not running they are under the roof and dry.

used power supplies do pop up on here quite often. I used a Maplin one at first then saw the bigger one for sale on a local site so upgraded.