Observatory 12v power supply?

[michaelmorris]

My new observatory is coming along nicely.  I'm presently planning out the electrics and thoughts are inevitably turning to choices of 12 power supplies.  With everything running I could conceivably pull over 8A at 12V.  In my old observatory I had a QJE QJ1863 regulated power supply giving 13.8v output rated at 10A (12A surge) which served me very well.  Unfortunately I can't find another QJ1863.  Can anyone suggest a good  stable 13.8v 10A or larger supply that won't break the bank?  

Thanks

[fireballxl5]

I've used a Nevada linear PSU to run a dual-scope imaging rig in my observatory for a number of years with no issues.  Looks like they've refreshed the design,  but equivalent I think to this one 

https://www.nevadaradio.co.uk/sharman-lm-30a-30-amp-analogue-display-linear-power-supply-unit-two-year-warranty?___store=nevada

 

[M40]

I use the nevada psw-30 power supply. It's currently £89 at flo so somewhat more expensive than your existing device but it hasn't missed a beat. I keep it outside in a heated enclosure year round. 

[Elp]

I assume you have a mains connection and ask if you need the 13.8V? May or may not be of use to you but the Pegasus mains adaptor is 12V 10A when normal adaptors are 5A.

[wimvb]

I use a MeanWell 12V 150W power supply. Put it in a plastic box with 12V car outlets. Nowadays it's attached to the base of a pier in my observatory. It has worked well for almost 7 years now.

 

[Adreneline]

1 hour ago, wimvb said:

I use a MeanWell 12V 150W power supply

+1

[david_taurus83]

On 25/03/2024 at 22:47, fireballxl5 said:

I've used a Nevada linear PSU to run a dual-scope imaging rig in my observatory for a number of years with no issues.  Looks like they've refreshed the design,  but equivalent I think to this one 

https://www.nevadaradio.co.uk/sharman-lm-30a-30-amp-analogue-display-linear-power-supply-unit-two-year-warranty?___store=nevada

 

I got one of these about 6/7 years ago and still going strong. It has been running 24/7 in the shed for the last couple of years now as it keeps power to the pier and dew straps to prevent condensation under the Telegizmo cover and also feeds 12v to the wife's barrel pond pump by the back door. Great investment. 

[david_taurus83]

16 hours ago, Elp said:

I assume you have a mains connection and ask if you need the 13.8V? May or may not be of use to you but the Pegasus mains adaptor is 12V 10A when normal adaptors are 5A.

I would always suggest using 13.8v as with smaller thinner cables feeding peripherals, there will always be voltage drop. Especially if there is need to run a long cable from source to mount. My Nevada unit is set to about 14v output and with the mount a few metres away and everything running the voltage at the mount is just above 12v.

[carastro]

Probably too basic for you Michael but I have normal main supply into the obsy and simply use one of these to run the 12V stuff.  Also you might not want the Cigarette lighter.  Otherwise I also bought a mains to 12V cable from an Astro retailer to power the mount which was around £34.

 

Edited March 30 by carastro

[Elp]

2 hours ago, david_taurus83 said:

I would always suggest using 13.8v as with smaller thinner cables feeding peripherals, there will always be voltage drop. Especially if there is need to run a long cable from source to mount. My Nevada unit is set to about 14v output and with the mount a few metres away and everything running the voltage at the mount is just above 12v.

I guess better to be over. But if that's the case why are all adaptors 12V? I usually use batteries and they run 11.5-11.8, never had a problem even in freezing cold temperatures. I have recently invested in some lifepo4 batteries for a modified rig, they however are gladly 12.8V.

Edited March 30 by Elp

[david_taurus83]

6 hours ago, Elp said:

I guess better to be over. But if that's the case why are all adaptors 12V? I usually use batteries and they run 11.5-11.8, never had a problem even in freezing cold temperatures. I have recently invested in some lifepo4 batteries for a modified rig, they however are gladly 12.8V.

The 12v adaptors are ok if you are using them as intended ie one for the camera, one for the mount etc If you try to use one to power everything, it will supply plenty of amps no problem but you may run into trouble with voltage drop. Thin cables between devices are the culprits.

[michaelmorris]

In practical terms for our uses, is it better to go for a switched power supply or Regulated (aka linear) power supply?

[Tomatobro]

Switched power supplies are small and efficient but poor when dealing with transient loads. Linear power supplies are big and heavy and not very efficient but are good at dealing with transients.

Linear power supplies are being phased out (EU directive).

 

[fifeskies]

I use a big linear power supply that gives plenty output to power everything and never dips voltage even with the mount slewing both motors at once. 

Multiple outputs, some to run dew heaters that I leave on if it's a damp cold night, (In my dome), to ensure my scope stays dry.

It also runs my LED based lighting both low level marker lights and bright lights when I need them. This includes external path lights.

I found mine used , they come up fairly often.

Very reliable.

 

[John_D]

1 hour ago, Tomatobro said:

Switched power supplies are small and efficient but poor when dealing with transient loads. Linear power supplies are big and heavy and not very efficient but are good at dealing with transients.

 

That's a bit of a generalisation. Well designed ( usually more expensive ) switched mode supplies can handle transients very well. Similarly, badly designed ( usually cheaper ) linear supplies, with insufficient smoothing capacitors for example, can have poor transient performance.

One point to note with cheaper switched mode supplies with multiple outputs is that only the main output is likely to be properly regulated. The secondary outputs may not be as good.

As with any engineering question the answer starts with "It depends ..." 😁

Edited March 31 by John_D
clarification

[Tomatobro]

1 hour ago, John_D said:

Well designed ( usually more expensive ) switched mode supplies can handle transients very well. Similarly, badly designed ( usually cheaper ) linear supplies, with insufficient smoothing capacitors for example, can have poor transient performance

True of everything. But I stand by my basic advice i.e.  a good linear PS would be my first choice.