Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_2019_sp_banner.thumb.jpg.a0ff260c05b90dead5c594e9b4ee9fd0.jpg

Recommended Posts

nice one im getting a goto and was just looking for a power lead as my garden is very dark and im lucky to have power in my shed to this would be great thanks :)

Share this post


Link to post
Share on other sites

Hi Andy.

This looks very good for the money.

Have you measured the output voltage on and off load?

It should be very near to 12V at zero load, and slewing the mount.

Although this supply looks like a decent regulated output switcher type, some of the specification doesn't quite add up.

12V x 2amp out = 24 watts, not the 36W quoted.

Also the 1% output tolerance is unexpected. Low cost supplies are usually 5% or worse.

Hopefully you have a good supply and the spec was copied into the listing by someone who doesn't know what they are doing. Just my suspicious nature coming in here.

Better to be suspicious than risk damaging a drive.

David.

Share this post


Link to post
Share on other sites

Looks good... but I hate it when in typical e-bay fashion they cut and paste the spec without reference to all the notes.

Keep us posted with how well it performs

Share this post


Link to post
Share on other sites

Shop recommended one of these for garden viewing:

12V 5A Car Socket Power Supply : 12V Car Accessory Power Supplies : Maplin Electronics

Says indoor use only, but in reality I presume this simply means dont get it wet!

People online seem to go on about regulated supplies, which I dont think this is...but Skywatcher don't say the supply must be regulated so I've taken a punt

Edited by Sandgrounderjen

Share this post


Link to post
Share on other sites

As a general rule, a regulated supply is important on any mount kit. It avoids risk of poor performance at best, going on to scrambled memory, through to blow up.

Unregulated supplies can give 18/19V at low load dropping to 12V in use. Some even do not have smoothing. This means the ouptut ripples from 19V down to 0V at 100 times/second. Can't see this on a voltmeter, oscilloscope needed! But handsets and motor drives can get upset. Some kit will tolerate this sort of supply, some kit won't.

The details of types and construction of power supplies is too much to go into here. So here is a simple test, using a cheap voltmeter.

Turn on the supply without any load connected and measure the output voltage. It should be 12V, within 0.5V.

Now connect a load of some known type to work the power supply to somewhere near it's rated output current.

Car side lights are typically 5W or 6W. That is about 0.5amps.

Interior lights are sometimes 10W, almost 1 amp.

Indicator/brake lights are usually 21W, that is 1.75A.

Headlamp bulbs are often 55/60W, or about 5amps.

Measure the voltage again while driving the lamp load. It should be within 0.5V of the off load value. If not, use a different power supply.

Edited by DavidValentine

Share this post


Link to post
Share on other sites
Shop recommended one of these for garden viewing:

12V 5A Car Socket Power Supply : 12V Car Accessory Power Supplies : Maplin Electronics

Says indoor use only, but in reality I presume this simply means dont get it wet!

People online seem to go on about regulated supplies, which I dont think this is...but Skywatcher don't say the supply must be regulated so I've taken a punt

Skywatcher do state that the PSU must have a regulated supply.

From the manual:

"The Synscan should be powered by 11-15V DC power supply (tip-positive) capable of producing continuous current of 2 amps min."

"capable of producing continuous current" means a regulated supply.

Peter

Share this post


Link to post
Share on other sites

The Maplin box identified by Wozza looks fine.

Any of the portable 'start/charge' type of boxes contain a decent size gel lead acid battery. Often 17Ah. So they produce a stable supply in the field.

If there is a small plug top type power supply included in the kit, this may be connected to top up the battery while observing. These usually provide only a low current and in practice will lengthen the time before a mount + heater, etc discharges the battery. As a guideline, suitable chargers typically take 50 to 100 hours to fully recharge the battery. A fast charger is probably unsuitable.

A free standing battery charger is definitely NOT suitable for connection to a live mount. The 4 or 5amp variety have the potential to convert mount electronics into a single use smoke generator.

Share this post


Link to post
Share on other sites

Thank you, it won't be, it's the scope my mum and dad are getting and they have a power socket in the garage so not much point them buying a power tank as they will only ever use it in their garden.

Share this post


Link to post
Share on other sites
Skywatcher do state that the PSU must have a regulated supply.

From the manual:

"The Synscan should be powered by 11-15V DC power supply (tip-positive) capable of producing continuous current of 2 amps min."

"capable of producing continuous current" means a regulated supply.

Peter

The specs on the website say its not regulated, but someone has asked if it has a regulated output and Maplin have said yes.

Have posted them a question asking if it is capable of producing a continuous current.

Would be very surprised if this is not suitable, considering it was recommended by a telescope shop...but better safe than sorry

Edited by Sandgrounderjen

Share this post


Link to post
Share on other sites

...well theyve replied in about 60 seconds...and alas its not capable...however the other highlighted PSU:

12Vdc 5A Power Supply with 2.1mm Tip : CCTV Power Supplies : Maplin Electronics

...looks like it will fit directly into the goto, so off to swap them over

...have now got replacement...plugs into scope just fine, not quite as snug as the supplied power cable.

Edited by Sandgrounderjen

Share this post


Link to post
Share on other sites

maplin offer a 13.8v regulated poser supply in various current ratings, from 3A to 10A, 13.8V Regulated Mains Power Units : Bench Power Supplies : Maplin Electronics however the advertised rating is for 50% duty cycle, so the continuous current rating is half that.

An alternative is something like

650654.gif

Retails for £42 from REGULATED 5 Amp 13.8V DC POWER SUPPLY - connevans.co.uk

The manual states that the 5A rating is the continuous rating. I currently (sorry no pun intended) use one of the Maplin 5A units in my obsy for the HEQ5, but looking to replace it with a 7A supply so I have enough juice for all the dew heaters, camera supply and still be able to slew the scope.

I would advise anyone thinks twice when using switch mode supplies

Edited by malc-c

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.