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EQ6 to DC PSU cabling...help!


Beardy Bob
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I'm planning on using a mains adapter

(13.8V Regulated Mains Power Units : Bench Power Supplies : Maplin)

to power my new mount (I haven't actually got it yet, but I want to plan properly!).

Do I literally snip the 'cigarette lighter' part off the end of the supplied cable and connect to the terminals of said PSU (given that the polarity of the two cables is obvious of course!)?

This seems to be the 'weak point' in all the cabling (with regards to exposure to moisture). I know we're only talking about 12V/2A at this point, but I wouldn't want my mount to get fried and I'm not happy with enclosing the PSU because of the heat build up.

Any advice from people using these maplin PSUs would be welcome.

Thanks, Bob

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You may well be right from looking at the picture. The funny thing is though, I've just checked astronomiser and there is no mention of using them at all.

Astronomiser - Automated Astronomy and AstroImaging Solutions

I agree with you, banana plugs would certainly seem to be the best option for excluding damp and dew from the connection. Strange that astronomiser doesn't offer that as an option! I guess that's where I need someone who uses one of these PSUs 'in the field' as it were.

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Guys, based on two years experience the HEQ5pro and the EQ6 will safely take up to 15-16V continuous. Helps the slewing!!

I use one of those 12V car computer step up transformers (160W) to get the higher voltage.

For the indoor 240/ 12V transformer, I cut the cable end and soldered a 12V car socket; then there's no difference in the input connections for the scope, dew heaters, Laptop etc etc.

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Bob

Stay calm! 13.8v is fine for the mount. A fully charged '12v' battery typically outputs at 13.8v. There should in addition also be a little headroom in the mounts electronics

So far as connecting is concerned, snipping off the gigar lighter end and connecting to the correct terminal will suffice. Better still, solder a couple of 'eyes' onto the bare cable and then attach to the PSU. There is an example on Astronomiser with these eyes attached to a power cable - I think it's for a Meade

Is this PSU to be used in an observatory? You should be OK so long as it's dry! I don't think the units are however rated for continued external usage eg on a portable unit where the chance of moisture ingress is that much higher. They usually have vent slots for the 240v transformer ... and that's a damn sight more problematic than worrying about corrosion on a 12v supply.

Steve

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It's just a standard 240V -12V, 5amp, regulated transformer ( I got mine in Oz) has the 240 plug on the end of the supply cable and a small "universal" socket on the 1.8mtr 12V cable. It comes with an array of different plug sizes to suit laptops etc. I cut the 12V end and soldered a 12V car cigarette socket ( came from a 12V car extension lead). This allows me to use the std 12V car plug on all the other gear.... if it's still not clear I'll get a couple of photos later.

Edit: just followed the link to the Astronomiser site, the ASTPSA is exactly what I soldered to the 12V lead from the transformer. Cut the eye lugs off and solder and sheath the connections.....

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Wicked. Well, that seems to be the connection issue sorted. My only concern now is a safety one! The PSU as a whole is definitely the 'weak link' if you like. I want to keep the damp off, but I don't want to enclose it in a box because of overheating. Unfortunately, that means that the 12v terminals are exposed and, like you say Steve, the unit has vents where water can access the mians voltage.

That said, merlin and martin don't seem to have any problems with their transformers out in an obs. Do you keep them enclosed?

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Bob

Martin makes a good point. If the mount is an EQ6 Pro, they draw less than 1.5 amps when slewing at max speed. On refelection, a bench PSU is a bit OTT and you could get a smaller enclosed unit which would be cheaper. Unless of course you are also intending powering some other 12v stuff from the same PSU

Steve

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My transformer sits quietly on the back of the desk and the 12V runs over to a 4 socket splitter at the telescope. One used (through the computer 12-16V transformer) for the scope, another to the dew straps, one for a 12V red lamp and another to a 12V "doggie bed electric blanket" which keeps everything dry and cosy when I finish!!!

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Bob

An observatory offers sufficient protection from the elements - not too many people seem to observe in the rain - and I would use a mains transformer under those conditions. I wouldn't be as confident in the open and certainly not on damp/dewy ground

Steve

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Cheers guys, that's all very helpful. Certainly a single transformer of a 'laptop-style' like martin uses would be much cheaper than a large bench one. I was considering the extra requirements of CCDs etc in the future, but for under a tenner for the type martin uses you can't go wrong!

Thanks again.

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I use the 12v 2A version on an HEQ5. I unplug the mains lead from it and thread it through one of the ep holders on the mount and re plug - keeps it off the damp ground.

I do the same for the camera supply as well 12V 4A version

I use this setup outside I should add through a RCD'd waterproof socket

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That 5A one is 24V but there is a 10A 12V one there, but they do a whole range so plenty to choose from. I got mine from Rapid Electronics. But I use a seperate one for the CCD as i have found that switch mode supplies dont like to be ramped up and down, I know under normal conditions there wont be any ramping while imaging but I'm playing it safe. The only reason I use them is they are small and not to badly priced.

For my HEQ5 Synscan it recommends 11 - 15V @ min 2A so anything in that range will do.

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