Ok stupid question time......

[Digz]

I've just brought one of these to power my mount and also power other items such as a guider and eventually a CCD camera:

30A 13.8V Switching Power supply : Amateur Radio Accessories : Maplin Electronics

Now my question is do I leave the voltage on the default 13.8v or should I be setting it to 12v?

I also plan on buying or making some cigar sockets to connect to the tongue connectors at the back am I right in thinking I can connect quite a bit to this and be ok? I.e. EQ6 mount, atik Titan, CCD camera and have spare capacity left over for dew heaters/tapes?

TIA for your help

P.S. hope this is in the right section.....

[malc-c]

13.8v is fine

[Bizibilder]

Just add the (maximum - eg a mount is around 1A tracking and 2A slewing) Amps for each item you connect. I doubt if you will get near to the 25A continuous max load for the rear sockets. A fully charged "12v" battery is usually around 13.8v.

[Digz]

Cheers Malc, I was thinking that would be the case but thought I'd better check before I do something wrong and knacker something else up, lol

[malc-c]

It would work on either 12v or 13.8v, but leaving at default won't do any harm. I have a fixed 13.8v 5A supply running my HEQ5, focuser, and Canon 400D psu, plus two dew heaters and everything has been OK for the past six months

[pete_l]

A couple of points:

First of all, some switchers are sensitive to short circuits. By "sensitive" I mean that it kills them, instantly. It might be worth a quick check of some ham radio forums to see if this is a problem with this particular product. A lot of switchers are short-circuit protected, but then you'd expect that to be listed as a feature.

If this does turn out to be an issue, you might be able to mitigate it by placing a current-limiting resisitor between the unit's output and your extension sockets. Something like 1 Ohm at 30 Watts (or make your own from resistance wire). It'll get warm, though. A fuse almost certainly wouldn't be fast enough, if this unit is not protected against short circuits.

Nextly, when you do add more outlets remember to use thick enough wire. Your average 7/0.2 hook up wire won't be sufficient for high loads.

[malc-c]

Didn't notice that it was a switched mode unit - I use the traditional regulated supply 13.8V Regulated Mains Power Units : Bench Power Supplies : Maplin Electronics

[Digz]

Didn't notice that it was a switched mode unit - I use the traditional regulated supply 13.8V Regulated Mains Power Units : Bench Power Supplies : Maplin Electronics

Does that make any difference? I.e should I have gone for anything different?

[Digz]

Pete thanks for the input I'll check it out and also make sure I get some thicker gauge wire etc.

[Digz]

Thanks for te reply Bizi, missed that earlier (trying to use my iPhone whilst out shopping!

[malc-c]

Does that make any difference? I.e should I have gone for anything different?

Not really, just that some electronics are prone to the interference and spikes that switch mode PSU's can induce on the mains. The advantages are that Switch Mode PSUs are more efficient as their design means less power is wasted in dissipating heat as their output stages are not driven 100% of the time.

[Digz]

Ok Malc, think I understand that, thanks for the info mate really appreciated :-)

[Digz]

Ok everyone, thanks for the help, much appreciated.

Pete - the unit is short circuit protected as well as having automatic current limiting - thanks for bringing this to my attention.

I have added up the amps of what I have (or will have shortly) and have 2amps for the mount (when slewing - hopefully on once a night assuming a single target night), 500mA for the Titan (although I doubt this will actually be ever plugged in) and potentially 4A for the QHY9 if used at 100% cooling (highly unlikely) so plenty or spare residual amperage for dew tapes and anything else I may want to plug in (possible netbook?)

Thanks again guys :-D