Telescope Reviews: Basic electrical question

NO offense intended, but your question is VERY confusing.

There are two different types of Emergency Car Starters.

The first kind uses jumper cables. Usually these also provide a standard 12 volt cigerette lighter female plug so that you can plug in things like your telescope or work lights. If this is what you have, you can simply get a cable from the telescope supplier with a male cigerette lighter plug on one end, and the appropriate mini-jack connector for the telescope on the other.

The other kind is like a brick. Radio Shack sells it. These have a Male cigerette ligter plug on them and to use them, by plug that into your car's cigerette lighter and let them sit for about 20 minutes, and then try starting the car. Again, you can buy a cable from the telescope company with a male cigerete lighter plug on one end and a mini-jack tip for your telescope on the other.

I have used the small "Brick" style and found that it is incapable of running a Go To telsecope for more than about 20 minutes. The Power Tank (The kind with Jumper Cables) can usually run a telescope for several hours. I have run two Go-to Telescopes at the same time for 3 hours with mine.

As for these other transformers, sometimes they will work. All of them have a label on them (or it is cast into the plastic) that identifies the voltage (most Go-TO telescopes take 12 Volts DC (12 Vdc). The other figure you see is typically something like "800 ma" which is 800 milliamps, or .8 amps.

Most GEM Go To telescopes only draw about .4 to .6 amps when they are sitting just sitting and tracking in Right Ascencion. Since the Alt/az Fork Mounted scopes have to run both motors to track, the actual current is usually about 1000ma (1 Amp) or even 1200ma.

When you are slewing across the sky, the motors (depending on the mount) can draw 3 and even more amps (3000ma).

Now the rating on these is usually the constant duty rating, which means that if you exceed that rating by up to 50% for a couple of seconds, it won't usually hurt anything.

But if you exceed that rating by more than 50% or for long periods of time by as little as 20%, you will fry the device. So, for a Go-to scope, figure that you need 2000ma constant duty and you should be fine.

If your scope is not Go-to, but rather has only RA drive, the draw is usually less than .5 amps (500ma). My Celestron Polaris mount will run all day on a single 9Vdc battery.

The other issue is that the mini-jack not only needs to be the right size (N tips and M tips are pretty common), it also has to have the right polarity.. For Meade and Celestron, this usually means that the center of the Minijack (the hole in the tip) has to have a positive voltage and the outside of the tip has to have Negative.

Sometimes this is also indicated by a little symbol on the device (not always).. The symbol looks like a "C" with a little circle in the middle and a line extending out with a "+" or "-" symbol pointing to the little circle inside the "C". This tells you the polarity of the jack.

Be aware that if you acidentally use a tip with the wrong polarity, it can immediatly fry your Hand Controller.

Now these little transformers RARELY come with enough baseline load capacity to run a Go-to telescope.

So, I am sorry but I am very confused about what you were saying in your post, but I hope that I have helped explain this.

What did your telescope come with? Did it come with a long cord with a mini-jack on one end that plugs into the mount and a Cigerette ligher plug on the other end? If so, it is simple.. Just plug it into the emergency starter into the cigerette ligher plug on it.

If your emergency starter only has jumper cables and doesn't have a 12Vdc Cigerette lighter plug, it is not going to be safe to use it to power a telescope.

If you need it for field use, get a power tank or an emergencey starter that has a cigerette ligher plug.

If you want to use it at the house, Radio Shack sells a 3 Amp 12 Vdc power suppl with a Cigerette ligher jack on it. These cost about $30 (on the web I have seen them for as little as $20). You plug these into the wall or an extension cord and plug the cord that came with the scope right into it.. I run two Go-To telescopes all the time off of mine and since they usually aren't slewing at the same time, it has always had enough capacity.

If your scope came with a long cord with a mini-plug on one end and a small transformer that plugs directly to the wall on the other end, and you want to run it off of a battery pack, you will need to buy a cable kit from Radio Shack..

The sell cords with male Cigerette ligher tips on one end, and a small connector on the other that can accept a variety of tips. If your Emergency Battery has a female cigerette lighter plug, you can buy one of these cables and the correct tip (Often the actually come with a few connectors, but Radio Shack usually also sells the individul mini-plugs seperatly too). Take your cable with the transformer to Radio Shack and show them the jack. They can give you the right tip.. Be careful though.. The tip can be plugged in so that the outside is negative and the center is positive, or if you flip the tip, the center is NEGATIVE (which you DON'T want) and the outside is positive. Again their is a little symbol moulded into these tips and the end of the cable so you can get it right (usually there is a little arrow on the end of the cable, and you insert the tip so that the arrow on the cable points to the "+" or "-" configuration).

Sorry for the long post but I tried to give you an answer for every possible configuration.

If I did NOT anwser your question, then I suggest you re-ask with this information.

Where are you now (Did the scope come with a Transformer type cable that plugs into the house plug and has a mini-plug on the other end) or did it come with a Male Cigerette ligher plug on one end and a Mine-plug on the other...

THEN tell us what you want to do (which I THINK is to be able to run the telescope off of a battery pack).

Regards.

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Celestron C14, CGE (Big Al)
Astro-Physics 6" f/8 (Buffy)
Televue 101 (No name, but I call it my Widescreen HD Space TV)

The night sky is my mistress. She seduces me away from all other lovers.