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I have recently had A Skywatcher Goto AZ and purchased 8 X 1.2 Rechargerble Batteries. I also have A Multi Voltage Transformer. I decided to try this as an alternative power source. I set it to 12 Volt D.C and plugged it into The Skywatcher Handset. The Handset lit up and proceeded to set up mode. As I was inputting my coordinates I noticed a smell of burning and The Handset became very hot. I unplugged everything and let it cool down. I then plugged in the battery pack and The Handset restarted and seemed ok but this time it wasn't hot and no burning smell. As I have no clue of the working of amps,voltage etc I was wondering if I did wrong by using The Multi Charger even though it was set to 12volts which is entered with a digital display.  Thanks.

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Never trust these things - always check the voltage with a meter. Also, if this is a constant-current charger the voltage may increase if the current draw is below the threshold the charger thinks it should be pushing out. In short, don't use such a device, use a standard mains PSU that outputs just a nominal 12v and which also offers a maximum current to satisfy the mount's requirements.

ChrisH

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You must, must, must read labels before applying power supplies.

Does the handset take 8xAA batteries, or is that the mount? And in any event, did you check that the lead tip from the transformer was +ve?

Hot and smoke is not good. You may get away with it, but not in the long run.

Check everything over as to power demands, then get someone knowledgeable to look over it: you'll learn that way as well. We've probably all been there and done that at some time.

Hope you get sorted.

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I notice in the manual for the mount it says: "The SynScanTM AZ should be powered by 11-15V DC power supply (tip-positive) capable of producing continuous current of minimum 1 amps."

What are the specifications of your power supply? 

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The 8 batteries supplied can be plugged direct into the handset for updating the handset via a laptop. If used for viewing the 8 pack then plugs direct to the mount and then the handset is powered from the mount using the plugs you use for plugging your landline phone into the wall. Think it's an RJ-45 lead.

The Power Source I tried was an A1 90 Watt AC/DC Universal Notebook Charger. The min output is 12v and goes up to 24v. I set it to 12 v and used Tip C which is 5.5mm x 2.5mm. I'm not sure what Tip Positive means. On reflection I think I was very reckless just going ahead without checking on here instead. Can any of you recommend a proper bit of kit I should be using instead of the 8 X 1.2 

batteries I'm using. They are eneloop  1.2 AA 1900 mAh. Thanks.

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Do your tips e.g. Tip C have two pins to plug into the end of charger lead? If so, you may see a + sign as an alignment mark on the end of charger lead. Lining up the + with the mark will give you a positive tip at the end - if not, it'll be negative. That's crucial. Without seeing what you've got, can't do much more.

As for your batteries, 8x1.2 rechargeables only give you 9.6v (8 x 1.2 = 9.6). Eight standard AAs will give you 8 x 1.5v = 12v.

Think I've just found your kit on Maplins - Tip C is POSITIVE on the INSIDE, and the outside of the tip is NEGATIVE. Check the alignment.

Is this it? https://maplindownloads.s3-eu-west-1.amazonaws.com/n40hj-Universal-Charger-Manual-7358.pdf

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I've had a look at the supplied tip that came with the mount and scope and the tips in my A1 kit and none of them have any markings. I think it will be best to stay away from The A1 although I have use it in the past to power a laptop which I think was 15 vol. But that's something different. As for the 8 X 1.2 batteries I did wonder at the time if they would be insufficient enough power for the mount or handset to work but I did get the info saying they were fine on another forum. So John thanks for all your help and guidance on this problem. I don't suppose you can recommend another alternative. They is A Skywatcher Power Pack on Amazon but at 58 sobs I just can't run to it at the mo due to other spen commitments. That why I though my A1 kit could do the job. Once again thanks very much. Regards Eifion.

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Wish I could help further, but I don't know your system and connectivity, so I'll defer to others.

If I need power supplies, I make my own where I can e.g. 240v PSUs (old computers), and tap off 12v, 5v and 3v. Also use old 12v car batteries, but you need to know what you're doing with circuitry.

You'll get it sorted, don't worry.

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As soon as I saw, I tap off ,and old car batteries I was lost. As I say I'm absolutely useless as far as anything electrical is concerned. Lol. I know I won't go plugging in things I'm not sure about again. Thanks John.

Oh the mount I've got is A Skywatcher AZ Goto. The instructions that came with it don't even tell you what Model it is. I think the instructions are standard for The Skywatcher Goto series of mounts.

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It is often best to check the voltage output by any Mains/DC unit. When I first bought my goto I bought a mains adaptor. It was produced for the scope and I bought it from the same place as the scope. First time I used it the scope dispaly stated "Over voltage".

I unplugged and tested it adn sure enough it was well over voltage, up around the 13-15 volts, on a 9v setting, as best I recall. Still able to use it as it had alternative voltage options and I chose one of these, the 6v option, and it was fine. Went back to let the shop know, just as information, and the proprieter was very off hand said I was doing the measurement wrong etc, etc, etc. That was the day I stopped buying anything from him.

You may find that a 12v supply for a laptop outputs 13-15 volts likely higher, they are at a higher voltage so they can recharge the 12v battery of the laptop. So say 2 or 3 volt more and likely a protection diode in there as well that drops about 1.5 volt. Every chance they will be outputting 15-16 volt.

You have been lucky, usually the Skywatcher electronics die very fast.

I use the Maplin L06BR on mine now. You select the conector size necessary and set the tip positive or negative as required, also set the voltage to the desired option.

Why was the power applied to the handset, thought it was applied to the mount and that it was then fed through to the handset. Thinking there may be a voltage regulator in the mount to handset side that drops the voltage.

What is the scope model also.

Edited by ronin

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I was puzzled about that. Usually the handset is powered directly when upgrading the firmware. 

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It may have been mentioned...I have a scope which can take 8 AA batteries but they don't last long . I suspect this is due to moving the heavy scope/motor.

I use a 'switchback regulator' , the formal name for the product with multiple DC voltage options and set to 12 V. I t converts AC power to DC and requires a power outlet to work . I usually add an extension lead to give me enough lead to the wall supply socket. It works well and the switchbacks are cheap...

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I just had a quick check of all the laptop PSUs here in my office and they are all rated at 19v DC output.  I am currently using the PSU off a Hard Disc Drive reader to power my Orion XT8g. It's rated at 12v DC output with a 2.5amp max draw. I measured it at 12.5v but that is acceptable and seems to work fine. I have seen similar ones on Amazon and Ebay for between €20 - €40

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Tip positive means just that if you have a volt meter check by inserting the red positive probe into the tip and the black prob onto the body of the tip and you should see 12v displayed if you have the minus 12v displayed in means it would be tip negative if this was the case your handset would be fried

It seems as your tip polarity is correct

I myself cut off the leads from the supplied battery boxes and wire them into a 12v 7ah alarm battery which lasts all night and has no leads trailing across the garden or to the car

Best regards Baz

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The problem with these cheap unregulated power supplies, is that they don't keep a constant stable voltage regardless of the load.

In your case, you didn't really do anything "wrong", although you had a 50/50 chance of frying your hand-controller not knowing the + and -, but you was lucky here.
The problem is really the power supply. It's set to 12V, but cheap supplies like this can easily deliver 15-16V and even more depending on the load.

I recommend you either stay with batteries, or buy a regulated power supply as a cheap unregulated on is really more about luck with sensitive electronics like these mounts and controllers.

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I agree with everyone that said stay with batteries.  However.  Telescopes tend to run from 12V. Actually that's a little white lie, they are design to work from automotive 12v supplies.  aka car batteries.    When fully charged they can give out 14v, but will drop down to 10v when completely flat.   This said, what I'm talking about here is clean power from a battery, not the noisy power that you get from cheap AC-DC supplies.

 

This is what I use to power my scope.  It is a little on the large side for that application, but I do have to say that it works well and powers everything (scope, heater, skyfi, cameras, and laptop!) for a night without any problems.

 

IMG_1443.JPG

 

Last year, I upgraded the setup and put the battery into a toolbox, which I modified to allow power output.  Here's my solution.

It's got 4 usb sockts & 4 12v sockets on the front.  The display is a power meter showing how much charge is left.   On the side there is an XLR socket that I use to power the scope and dew heaters (it's a dedicated socket with fastens securly, no chance of the plug dropping out)

Photo 23-07-2016, 17 14 11.jpg

 

I do recommend that you don't use 1.2v rechargables... here's why.

The 8 * AA adapter that came with the scope is meant to work with 8 * 1.5V aklaine batteries.  1.5 * 8 = 12v, and typically they will go flat when they drop in voltage to about 1.1 volts each (8.8 volts), and even that is generous.     My Meade scope (using the autostar) thinks that batteries are flat when the voltage is about 10v (about 1.25v per cell).

Now, consider your 1.2v batteries.  when fully charged, my Meade scope will still think the batteries are flat.  So that's a no go.  1.2 * 8 = 9.6V.  So, this means that if your scope is generous and considers batteries flat when they are are 1.1 volts each, you'll be able to have a voltage drop of about 0.8 of a volt across all the cells.

Now, assuming that you are in the UK.  Using a scope at night, you are likely to get that happen from temperature alone.

 

This is why pretty much everyone forgets about AA or variations on that theme (including the bigger D cells)  and uses something with alot more grunt behind it.

 

I personally feel that this is the minimum that you can get away with...

http://www.maplin.co.uk/p/yuasa-12v-sealed-lead-acid-battery-7ah-1-pack-mg47b

 

This would still be a step up from AA's, but might still not be powerful enough for a whole night session.

http://www.maplin.co.uk/p/6v-sealed-lead-acid-battery-45ah-1-pack-l21ac

 

These days people are also talking about using 12 volt lithium batteries. Although, I've not looked into this one myself.

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19 hours ago, cjdawson said:

I agree with everyone that said stay with batteries.  However.  Telescopes tend to run from 12V. Actually that's a little white lie, they are design to work from automotive 12v supplies.  aka car batteries.    When fully charged they can give out 14v, but will drop down to 10v when completely flat.   This said, what I'm talking about here is clean power from a battery, not the noisy power that you get from cheap AC-DC supplies.

 

This is what I use to power my scope.  It is a little on the large side for that application, but I do have to say that it works well and powers everything (scope, heater, skyfi, cameras, and laptop!) for a night without any problems.

 

IMG_1443.JPG

 

Last year, I upgraded the setup and put the battery into a toolbox, which I modified to allow power output.  Here's my solution.

It's got 4 usb sockts & 4 12v sockets on the front.  The display is a power meter showing how much charge is left.   On the side there is an XLR socket that I use to power the scope and dew heaters (it's a dedicated socket with fastens securly, no chance of the plug dropping out)

Photo 23-07-2016, 17 14 11.jpg

 

I do recommend that you don't use 1.2v rechargables... here's why.

The 8 * AA adapter that came with the scope is meant to work with 8 * 1.5V aklaine batteries.  1.5 * 8 = 12v, and typically they will go flat when they drop in voltage to about 1.1 volts each (8.8 volts), and even that is generous.     My Meade scope (using the autostar) thinks that batteries are flat when the voltage is about 10v (about 1.25v per cell).

Now, consider your 1.2v batteries.  when fully charged, my Meade scope will still think the batteries are flat.  So that's a no go.  1.2 * 8 = 9.6V.  So, this means that if your scope is generous and considers batteries flat when they are are 1.1 volts each, you'll be able to have a voltage drop of about 0.8 of a volt across all the cells.

Now, assuming that you are in the UK.  Using a scope at night, you are likely to get that happen from temperature alone.

 

This is why pretty much everyone forgets about AA or variations on that theme (including the bigger D cells)  and uses something with alot more grunt behind it.

 

I personally feel that this is the minimum that you can get away with...

http://www.maplin.co.uk/p/yuasa-12v-sealed-lead-acid-battery-7ah-1-pack-mg47b

 

This would still be a step up from AA's, but might still not be powerful enough for a whole night session.

http://www.maplin.co.uk/p/6v-sealed-lead-acid-battery-45ah-1-pack-l21ac

 

These days people are also talking about using 12 volt lithium batteries. Although, I've not looked into this one myself.

I've been using a 12v 12AH lead acid sealed battery and one my AZ MOUNT with my 130x650 it's fine never been an issue.... But last night using same fully charged battery on my eq 5pro and 200p it caused no end of problems with slewing and the goto set so your absolutely right in the above post

Best regards Baz

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As I always have to travel to view or image I always have the car with me. I simply put 2 crocodile clips direct to the battery terminals. On my pillar mount I made a waterproof junction box with a 12v input and 3x 12v outputs. I use one for the mount and one for the 3 cooling fans on the end of the scope. I have used this all night with no problems what so ever. Cheap and simple but it means having the car next to the scope.

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15 minutes ago, D Wright said:

As I always have to travel to view or image I always have the car with me. I simply put 2 crocodile clips direct to the battery terminals. On my pillar mount I made a waterproof junction box with a 12v input and 3x 12v outputs. I use one for the mount and one for the 3 cooling fans on the end of the scope. I have used this all night with no problems what so ever. Cheap and simple but it means having the car next to the scope.

This is indeed a great way to do it when it comes to capacity, however there are some things one must keep in mind.

1. Some cars have poor quality alternators and regulators which Might cause troubble for the scope (in form of voltage exceeding 15v or noice/voltage spikes).

2. A powerful starter motor, especially in combination with cold condition and/or a worn or drained battery can both cause voltage drops low enough for the scope to stop working, or cause voltage spikes so high it can damage the scope.

3. If using the car as an observatory, it can get cold. Many are probably tempted to regulary start and stop theengine with full heatingon. The car at idle with lot of electonics on, will actually drain the battery even with engine running. Repeating this multiple times a night might leave you with such a drained battery you wont be able to start the car in the morning when the session is over (either due to battery being too drained to start engine, or battery drained enough to allow it to freeze if its ice cold outside). This is most common on cars with smaller and worn batteries, while its ice cold outside.

Now these 3 things are probably more important for people like me living in Norway, but thought its worth mentioning anyway. The last thing you want is either a fried scope or a car not starting out in nowhere. :)

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A full charged 12v battery should carry approx 13.5 v, the alternator issue would only really be a issue if the car engine was running, saying that unless it's a really old car it will have very good suppression on the electrics and wouldn't be any issue at all

Again the volt drop when cranking the engine would definitely be a problem

Baz

 

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