EQ mount power supply

[mandownsouth]

Hi, just registered as a newbie from Sth Oz. I am running an HEQ5 Pro and wondered what the norm is for power supplies. Seems there are diehards that won't use anything but batteries.

I would, however, like to consider the use of a power supply when I eventually get myself organised in a POD. Are there any lilmitations with stepper motors, particularlly in the guiding mode for astrophotography, that proclude the use of power supplies running via a regulator - ie switched mode device (7812 + a current regulation using a 2N3055) - that steer the thinking toward batteries?

I understand that a good size battery may well be those used to propel the electric scooters that the more senior members of our community use. Somebody's thoughts on this option would be appreciated too thanks.

mandownsouth:)

[Wombat]

Hello,
I use a heq5 pro mount for my ed80 and 9.25 sct, I bought a power supply from myastroshop.com.au that does the job. It plugs into the mains supply and drops the voltage down what the mount requires, the power supply is made for this mount.

[pjphilli]

Hi Des

The subject of power supplies for HEQ5Pro mounts has come up before and you may find information by searching mainly on the Equipment Discussion forum. The handbook says you require 11-15volts with a minimum of 2 amps. In an emergency I have run the mount on a 12volt 1amp 7812 regulated power supply and it seemed to run OK. A regulated 240volt to 12volt power supply using a 7812 plus a 2N3055 to provide at least 2 amps would be OK. (Tip - depending on how you connect the 2N3005 you may notice that the output voltage is a bit below 12 volts.
Although this will work with the mount you can trim the voltage up to 12 volts by putting a diode between the 7812 common pin and earth. This tricks the 7812 to operate with an output of about 12.5 volts thus allowing for the drop through the 2N3055). I find a cheap car battery is fine for portable use but for home I settled on a JayCar 60w 12VDC switched mode power supply cat no: GH1379, about $30)
The five amp capacity of this supply lets me run extra astro gear with no
power capacity problems.

Cheers Peter

[peter_4059]

Des,

I've been using a regulated 12V switchmode powersupply for years without any issues (its a DSE M9940 however I think they now only sell the M9941 which is similar but has adjustable output voltage).

Peter

[RobF]

Yes, I've been using the M9941 precursor with no adjustment for over 2 yrs without issues. I take care to keep it off wet ground and covered from dew if at a dark sky sites, but at home its happy sitting on the tiles under my mount.

Bought originally when I was fretting that my battery may not be behaving all night. If you know you'll have access to 240V well worth having something like this.

Decent gel battery and charger or even a Jumpstart pack will set you back way over $100
I did invest in batteries, but if you eventually get into astrophotography you start having dew heaters, laptops, cooled CCDs and all sorts of things that can require SERIOUS juice. I sometime wish I'd confined myself to 240V sites and spent the money on more filters or another DSLR lens.

[Tandum]

I use an old car battery in a square bucket. I run a normal battery charger across it which I recently upgraded from a 3amp to an 6amp charger to supply a new camera. I run everything off this battery. Using a battery like this makes you immune to short power outages but I wouldn't expect it to run the gear for any more than half an hour.

[mandownsouth]

Wow...wonderful options all round. Thanks heaps to all of you. I think ultimately I may have to have a battery back up. I am encouraged that switched devices don't appear to stymie the steppers and I have both agencies (DSE and Jaycar) as options - problem may well have been easily solvered.
mandownsouth

[bartman]

Hi Des, just a word of warning.....I bought a 12v dc/240 v ac power supply from jaycar with the interchangeable plugs. The plug doesnt fit tightly in the EQ mount, so sometimes - just at the crucial moments of course- the power cuts out and the mount stops!
Only one plug fits but not tightly so I tape it to the mount.
Bartman

[mandownsouth]

Thanks Bart, I had been wondering about the integrity of this type of plug connector. It had occurred to me that there is every chance in the world of it doing exactly as you say because of all the other bits and pieces that will be around the mount not to mention the clumsy hamfisted user waving my arms around at something speccy on the screen an knocking the jolly thing out. Point well taken and apprecited for sure.
Des

[mswhin63]

I have also been considering the best option, and decided only last night a Power Supply is better than batteries. I have been running my mounts for a while and at home realised it would be better to run the mount on power and when I go to remote sites use the 750W inverter to run everything. I hate lugging the 80AH batteries around in my backyard.

[pjphilli]

Hi Malcolm
I came to the same conclusion as you and now use a mains supplied power pack for my backyard astronomy. Just a thought about using the mains in the dark outside. Modern houses have good earth leakage circuit breakers that can protect against fatal shocks. My house is old so I bought (at Bunnings) a small earth leakage breaker that I always keep plugged in between my inside power point and my backyard extension lead. You never know when you are fumbling around in the dark perhaps on a dewy night.......
Cheers Peter

[mswhin63]

For running a cable out to you location in the back garden, you can purchase extension cable suited for such a job. Sealed units that are splash proof. I have a less intense extension lead which I use for home and for remote sites.

In remote locations I leave the inverter and batteries in the car run the extension lead outside instead of lugging batteries around. Much better on the body.

You could also get stands to place the extension lead above ground to you location, but the specific cable would be cheaper.

[mandownsouth]

Hi Guys,
For what it's worth is there really a problem to be bothered with earth leakage protection with, for example, double insulated aparatus like that of pjphilli (JayCar 60w 12VDC ) and I suspect the M9941 used by peter_4059 and RobF. By all means use it if you think it safer - that's always a priority. Electrically though I doubt much has been gained. Prepared to be corrected on this if someone wishes.
mandownsouth

[peter_4059]

I keep the M9941 in a plastic box to keep the dew off it. In any case our house has earth leakage protection on all GPO's.

[Irish stargazer]

For those who need plenty of amps, a deep cycle battery and money is no obstacle

http://www.raysoutdoors.com.au/online-store/products/Waeco-Cool-Power-Deep-Cycle-Battery-Pack-12V-RAPS36.aspx?pid=310026#Description

[mswhin63]

For a EQ5 that will be fine, but if you want to upgrade and get more gear 36AH wont cut it.
I use 80AH and I dont even use DEW Heaters yet, and I wonder if I have enough. I have not measured the current draw from my equipment only used batteries I already had available.

[Helo]

I am setting up my obs and seen various threads with concerns about power drop out, spikes etc. which leads me to think, at least for my scope and cameras, I will use a deep cycle battery of about 100 AH. My question is, how and when do you recharge these? Can you recharge as you use it as this would seem to possibly have the issue of potential spikes? :thanx:

[mswhin63]

I don't think spikes are an issue but I usually charge it up after every evening but I have charged it while observing. Float charge is commonly used for remote site which is design to top up batteries. That was the days when I service Goldfield railway network radio site which ran purely on solar and diesel.

For the mount and camera I only use 1 20AH battery now but only just manages one night. Usually by 2 or 3:00am the mount light starts to flash. I am usually done by then even on a remote site during summer. Winter is a different issue so i would suspect I will use 2 batteries