Re: 12V Power supply otions....


"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:ddevcs$nei$1@xxxxxxxxxxxxxxxxxxxxxx
> adm wrote:
>
>> "Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
>> news:ddd6ca$fc3$1@xxxxxxxxxxxxxxxxxxxxxx
>>
>>>adm wrote:
>>>
>>>>In my quest to have the LX200 and DSI set up outside but controlled from
>>>>inside, I am looking for a decent 240V AC to 12V DC power supply.
>>>
>>>I use a nominally 13.8v ham radio PSU (the sort that Maplins and others
>>>stock with two banana plug terminals on). Easily meaty enough at 4A for
>>>my dewheater and fullrate slew to object.
>>
>> Yeah - I saw one of those for £34 or something....but......isn't 13.8V
>> too high for the LX200GPS ? I though I read soemwhere (MAPUG ?) that it
>> needs to be 12V, not 13.8 and that it was the non GPS LX200s that used
>> 13.8V
>
> I don't know offhand what the voltage spec for the GPS LX200 is. The
> original LX200 was *designed* for 12v nominal and "upgraded" to 18v with
> no actual thought about the consequences. Several components are stressed
> if it is run at full 18v (and the official Meade 12-18v DC converter is
> one of the worst self-immolating pieces of shi^d^d^d bad design you are
> ever likely to see).

Ah......after a bit more reading on the subject, I was confusing
myself......the orignal Lx200 was upgraded to 18V, not 13.8V.

>
>>>>I presume that 800mA will be OK for the scope itself, but the DewBuster
>>>>spec says it needs a 3A rated supply.
>>>
>>>800mA will be marginal for the LX200 and may well blow its fuse on fast
>>>slew if the thing momentarily stalls (and on 12v this is not uncommon).
>>>Meade upped the voltage spec to nominal 18v to avoid motor stall issues.
>
> If the GPS really is specced for 12v then they have changed the motors. I
> would have thought they would make it so it could tolerate a nominal 12v
> lead acid battery though since they are regularly used that way.

I guess it does - as that's what I use now ! I was confusing the 18V and
13.8V......

>
>>>But it is noisy on 18v so I find 14v PSU (or a charged lead acid battery
>>>about right). Halfords do a self contained charger and battery too.
>>
>> I have one of those already ! I want to get away from lugging it outside
>> all the time, and especially being frustrated when I realise the damn
>> thing isn't charged up and needs to be charged for hours before I can
>> power my scope !!!!
>
> Recharge it immediately after using (and once a month otherwise).

I try to. But at the end of a long night, sometimes I forget to do
so.....then I end up with a nasty surprise the next night.

>
>>>Check MAPUG threads for additional details.
>
>>>BTW I would not run signal cables parallel to 240v mains wiring.
>>
>> It's non-optimal, I know ! I could run the data cables in a separate
>> conduit though - the distance is only around 10M or so.
>>
>>>And USB 2.0 will not like running very far and working either.
>>
>> I know - but then again it isn't very far.... I wish I could find a
>> single 15m USB2.0 active extension cable rather than having to daisy
>> chain several together.
>
> I think the longest I have ever seen are around 16' but I haven't really
> looked very hard.

That's the longest I can find as well....


.

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