12 v wall adapter

[ae2411 (Ervin)]

Hi all
just a tought.... if you have a goto mount and wanna run the telescope from wall adapter you need a 12v power adapter. I read the comments here and no one mentioned one and may be the most convenient solution
Most of us have a fast charger for AA or AAA batteries and the wall adapter on those things output 12v 2.5 amps or close. My is a duracell 30 min charger 12v 2.5 Amps.

[acropolite (Phil)]

I wouldn't be risking an experiment with a fast charger. Your fast charger may or may not be a constant current device, it could be autosensing and/or it could be that crudely designed that it relies on the battery load to regulate the output.

Save yourself a possible disaster and go to Jaycar and buy a 12 Volt switchmode supply.

[MrB (Simon)]

I don't think he means using the charger itself, just it's power supply(Wall Wart)

But agree it's risky, as mentioned the supply could be badly regulated, not regulated at all(tho most scopes would probably have supply conditioning built in), or even have AC output(tho not likely, I have a couple)
Also check the polarity of the plug and socket match, some are positive tip, some negative tip.

Agree, look for a good Switch-Mode supply, but before spending around $40 at Jaycar for a new one, check your local second hand stores like pawnbrokers(Cashies etc) or Good Sammies, Salvo's, the weekend cash-n-carry/car boot sales, garage sales or whatever, you can usually find a suitable ex-mobile phone or laptop supply for only a few dollars.

[netwolf]

I was also thinking of getting some thing like this for home use. But I have two options. I saw a 12V Switchmode power supply which had a cigerate lighter output. But I have read the Switchmodes are not good in outdoor situations especially if there is dew around. The Second option and I am not sure this is a good idea or not. Is to plug my rechargeable jumpstar battery into the 240AC supply for recharging but at the same time plug into the cigarette lighter output to run my equipment. Is this safe to do? Would this provide a regulated supply? I have a Bunnings GMC 17AH unit. How much current can i expect to get from this in this setup?

Regards
Fahim

[Ian Robinson]

http://cgi.ebay.com/KENSINGTON-K3340...806251112r9948 would do the trick.

Or a 220VAC - 12VDC plug in transformer http://parts.digikey.com/1/parts/730...0080e-p5p.html , see http://www.cui.com/pdffiles/DPD120080E-P5P-TK.pdf

Pretty cheap , heck I might get one just so I have it if I ever need it.

[Ian Robinson]

Originally Posted by netwolf

I was also thinking of getting some thing like this for home use. But I have two options. I saw a 12V Switchmode power supply which had a cigerate lighter output. But I have read the Switchmodes are not good in outdoor situations especially if there is dew around. The Second option and I am not sure this is a good idea or not. Is to plug my rechargeable jumpstar battery into the 240AC supply for recharging but at the same time plug into the cigarette lighter output to run my equipment. Is this safe to do? Would this provide a regulated supply? I have a Bunnings GMC 17AH unit. How much current can i expect to get from this in this setup?

Regards
Fahim

1 amp for 17 hours .

[netwolf]

Ian, but if it is on the charger will it still only provide this for 17 hours? Also you could look at that ratio as 17A for 1 hour.

[acropolite (Phil)]

Ian, but if it is on the charger will it still only provide this for 17 hours

depends on the current supplied by the charger, if the charger supplies .5A then you can add that to the amp hours available so if you can draw 1.7A for 10 hours the .5 would allow you to draw 2.2A. Batteries are generally rated at C/10 or C/20 (Capacity in AH/10or 20) therefore a 17Ah battery will should give 1.7A for 10 hours. As the current drawn rises, the formula becomes inaccurate, so a 17Ah battery supplying 7 amps will supply that current 2 hours or maybe less. It's a good idea to limit your discharge to less than 50% to prolong the battery life. As a rough rule of thumb, 50% discharge on a 12V lead acid type battery is reached when the no load voltage is 12Volts, completely discharged is around 11 Volts. SLA batteries have a very poor cycle life if heavily discharged. It's also important to recharge as soon as possible after discharging.

[Ian Robinson]

Just discovered I already have one , came with now defunct and long since binned Nokia 6110.