Regulated Power supply

[sadia]

Sorry for posting another thread on this but I am just too confused about all these terms like Voltage, amp , regulated, unregulated. I tried to read all the relevant post here on similar topic but still couldnt be sure so I thought I better ask the questiong straight and look for a straight answer:

Equipment list requiring power

Mount: EQ6
CCD Cam: QHY8
Dew heater: Kendrick fire lite (12v 1.5a max)

What I am looking for:
1. something that will power these equipment atleast for a night
2. Something with in $100-$150 if possible
3. Needs support 3/4 ciggie socket to power the above equipment


If you can point me to a direct product link from andrews or jay car or dick smith that will be most helpful because I am quite sure i have a slow brain to figure out myself what i will need exactly.

thanks in advance :)
Sad

[erick]

Sad, search for this one from Dick Smith:-

Lab Power Supply 13.8V DC 23A


Mains in. At $99, this is a ripper!

Can be adjusted down to closer to 12V output, if that is preferred. A ciggie socket on the front, terminal posts on the rear. 23A should handle everything!

[Shaun]

I have never used one of these but is designed for scopes

http://www.yorkoptical.com.au/Home/tabid/36/ProductID/109/Default.aspx?utm_source=getprice&utm_medium=cpc

You can also get a discount being a member of IIS

http://www.yorkoptical.com.au/ShoppingCart/IceInSpace/tabid/988/Default.aspx


P.S. i know Andrews sells them aswell

[sadia]

Thank you for the quick reply Eric. If I leave it to default on 13.8v will it blow up anything :)?

[erick]

Now, to explain the rest in a simplified way:-

Voltage:- The electrical potential, measured with a voltmeter. Written as "V". A car battery is around 12 V DC (direct current). Household mains power is 240 V AC (alternating current). An AA battery is around 1.5 V DC. A rechargeable AA battery is around 1.2 V DC.

Amperage:- The electrical current that flows through something. You can measure with a ammeter. Written as "A". Sometimes you will see it written as mA = milliAmp = one thousandth of an Amp.

Items are often marked with the voltage required and the amps that they will consume from that voltage. The amps often vary depending what the equipment is doing - eg. is the mount slewing or just tracking? Is the heater on or off.

Wattage:- Equals voltage x amperage. Written as "W". 1 V x 1 A = 1 W. Sometimes written as mW. Also can be stated as "power".

Equipment might be marked with the wattage it will consume rather than the current. If you know the voltage needed, you can work out the current using W/V = A

A "regulated" power supply contains circuits that keep the output voltage the same regardless of the amount of current being drawn from it - up to the maximum of the supply. Most things work happiest if the voltage is not varying - so a regulated supply is often the best. The Dick Smith one is regulated.

An "unregulated" supply does not contain these circuits, so can be made more cheaply. The sort of place you might use an unregulated supply is for a resistive heating strap where all that really matters is the wattage that is being generated by the strap and not the voltage nor current in particular.

Can you look at the manuals/plates on each of the equipment and work out the voltages and current requirements? If all are 12V, then you need to add up the maximum current needs. Then it's best to choose a supply that will deliver at least 50% more than this so it doesn't have to run at its maximum.

Eric :)

[erick]

Probably not, but......................?

Check the specifications for the equipment - looking for maximum voltage input. If they say 14, 15 16 V - OK.

But, I'd adjust it down if they say they really want 12V. Get the Dick Smith folks to earn their money. At the counter, after you have paid (or maybe before!), get them to open the box, plug it in, put a meter on the output, check it reads 13.8V, then insert small screwdriver in the adjustment hole on the bottom and turn it down to the minimum - probably under 13V - mine came right down to close to 12V. At the moment, I use mine to power dew heating through a Thousand Oaks controller - only drawing some 4A max, as I recall.

You'll maybe need some additional cables - splitters to two ciggie sockets - ciggie extension cables and the like. Dick Smith will sell these.

I got my 23A supply on a good special :) But the extra cables weren't that cheap :sadeyes: so I bought some, then got parts from Jaycar and made up my own. :D

[Robert9]

Eric, is the Dick Smith Lab supply powered from the mains? My impression is that Sad wants something like a battery pack - perhaps a jump-start. I run my Nexstar from one of these together with a dew heater and get at least 5 hours running and probable more. I don't believe the 12 Volt requirement is a problem. This is just a nominal voltage and 13.6V won't blow anything.
Robert

[sadia]

hmmm good point Robert, and yes I am looking for something that can provide me power when i take my set up outside in a remote location. So do i need to worry about regulated/unregulated thing with a battery pack or jump starter?

[Shaun]

Not sure if you caught my post but it is what you are after at the price you wanted.

[sadia]

Thx Shaun,
I had one of the 7ah one which is already dead (should have taken better care i guess). I found that 7ah one was a bit too less at times.

I am a bit worried to get one again due to the fact that the first one didnt last long and doesnt have enough power to last a long full night.

[Shaun]

Thanks for the info i didn't know about that have never used one, i might make a DIY out of car battery or something.

[erick]

Yep, it's mains.

[Robert9]

Sad,
The jump start I use has a 17AHr capacity which is the same as for the Celestron Power tank. If I remember correctly from when I bought mine, there is also a 24AHr unit available (more expensive). I got mine from Super Cheap Autos on one of their 20% discount days for $63.
The important thing with them is to not let them stay discharged for long periods of time, and this applies to all lead-acid batteries. I have run mine successfully for 2 consecutive nights on many occasions and not had any trouble. When the clouds roll in, I shove it on the charger and tend to leave it there as the units have a built-in intelligent charger which won't overcharge, just maintains the battery at full capacity.
As I said on my previous post, the 12Volt required (unless otherwise stated in your instructions, is probably a nominal voltage and running your scope at 13.6V from a fully charged 12 Volt battery is unlikely to cause any problems. Check with your scope supplier.
Robert

[sadia]

Thank you everyone. I think now I know what I need. Paid a visit to Dick smith and Jay car....will be dropping by super cheap autos this weekend I think.

Regards
Sad

[Shaun]

13.8v won't be a problem, i used to run C.B. and we used 13.8v regulated power supplys but then you could put it in the car np, only problem we had is if the power supply was unregulated you got a bad hum over the radio, but the power packs that come withmounts and stuff are not regulated so this would not be a problem.

[BC]

Hi,

I'm reading this thread with interest now that my EQ6 is having trouble behaving with the Super Cheap battery pack. The voltage shows no better than 12.3 and when aligning, the slewing draw may cause it to drop too much because it is going all over the place and fails alignment. I'm looking at this Dick Smith unit (Lab Power 13.8V 23A). Does anyone know what "switch mode" is. Does this affect continuous supply?

Thanks,
Bruce

[mswhin63]

Possibly good for starting currents for cars, but heard it's terrible for continous operation.

23A a bit overkill and requires 240V power which can be awkward for portability.

If you measured the voltage at the motor terminals then wiring thickness maybe the issue.

Batteries have an internal resistance, some high for continuos operations, some are low for high current operations. Resistance is a key factor in supplying the right voltage/current to the device being used. Keep the wiring resistance as low as possible maybe the main problem. But if you are measuring the voltage at the battery then there is not enough power to supply the motors.

[mswhin63]

Switchmode is a type of power supply converting the 240V to the necessary voltage.

Switchmode runs higher efficiency and lower weight as the transformers are hell a lot smaller.

Instead of transforming 50Hertz it transforms the voltage at many kilohertz just above audio frequencies. (Too technical sorry)

Noticable when a transformer starts to fails get a high pitch screamer.

[BC]

The voltage reading came from the hand controller readout (a handy feature). I agree the 23A is way overkill, but there doesn't seem to be a unit about half that size. I'm not worried about the power lead; I set up in the courtyard outside the house.

Bruce

[mswhin63]

Take a look at this link and browse around. You can order from this site.

http://www.altronics.com.au/index.asp?area=prod&grp=464

http://www.altronics.com.au/index.asp?area=prod&grp=263

http://www.jaycar.com.au/productResults.asp?FORM=CAT

http://www.jaycar.com.au/productResults.asp?FORM=CAT

I have other suppliers but generally unable to supply PSU's quickly because they are not stock items for me.

[lacad01]

Think the Jaycar links below aren't complete :shrug:
Found this though as a possible solution to some of my power needs:
http://www.jaycar.com.au/productView.asp?URL=index&ID=MP3242&CATID=27&SUBCATID=381
(12V 5A switchmode PS)

[pmrid]

I run my EQ6 off one of these and it copes well except that the plug into the EQ6 mount itself does not sit as securely as you'd like. I found I had to use some adhesive tape to keep it from wriggling out during the course of slewing and so forth.
Peter