Linear power supply for 383L+

[MG01]

As I'm about to jump to the dark side and dip my toe into CCD imaging I wondered if anyone can recommend a good linear power supply? 

My current switched mode is only 6A and doesn't have much headroom so I thought it might be wise to look into a new PSU and since I've read somewhere that this camera may benefit from a linear supply I thought I'd head down that road.

I guess there are plenty of open cage type ones available from Rs and the like but I figured there's probably plenty of folk here who've tried and tested a number so thought I'd ask. 

Thanks

 

[tooth_dr]

Not linear, but one I use and seems to work perfectly well.

https://www.firstlightoptics.com/batteries-powerpacks/nevada-psw-30-25-30a-switch-mode-power-supply.html

[david_taurus83]

I've had a few cameras and mounts since I started this hobby and I've never seen my power usage exceed 3amps. My current setup usually sits at just over 2 amps when camera cooler is on, mount running, dew straps etc. I do use a linear Nevada PSU with 13.8v to the pier at idle and with everything running is usually around 13.0v. My suspicion is that a lot of people use 12v AC to DC power bricks and when they encounter issues they are suffering voltage drop due to thin cables between devices, not exceeding the rated current for the power brick.

If you can get 13.8v at your mount then I think your 6A supply will be just fine. 

[Carbon Brush]

Something often forgotten is that many devices do not take a constant current. Electronics (camera, mount, computer) can take current pulses in the millisecond region. It is voltage drop at peak current that is the problem.
But if you use an ammeter it only shows average results, disguising the problem.

As a general rule, apply as many of the following as you can to ensure you have minimum resistance between power supply and point of load.

Given a choice of screw terminals or cigar plug on the PSU, use screw terminals.
Keep the cable run between PSU and mount as short as possible.
Use the thickest cable from PSU to mount that you can reasonably handle.
Avoid the cheap DC barrel connectors on equipment. Replace them by something better. Yes it voids warranty but improves reliability.
Fit a local decoupling capacitor at the mount. Several thousand microfarads. This will provide  energy for the current pulses.

All of the above can be done in warm and daylight, allowing successful operation in the cold and dark.

HTH, David.

 

[Tomatobro]

Linear power supplies are big, heavy and not very efficient but are very good at coping with transient loads.

Switch mode supplies are small, lightweight and very efficient but outputs can be noisy and not very good at coping with transients.

Radio ham shops are a good place to look for quality linear power supplies and many have used equipment sections.

 

[tomato]

@Tomatobro sourced a Nissei DPS-300GL 30A linear PS for my dual rig set up. Like he says, its big, heavy and a bit noisy and the waste heat it throws off helps keep the warm room warm. But more to the point, I have never had any power supply issues to the equipment, with up to 8 eight items drawing power from it.

 

[scotty38]

I've got the same one @tooth_dr linked to, never had any bother with it.

[MG01]

Thanks everyone...I was just looking a the following second-hand Kenwood...https://www.hamradio.co.uk/used-equipment/kenwood-ps-52-used

My peak power draw is something like this: (nicked from a post I made earlier today about general settup)

At the scope I have to accommodate the following:

• NEQ6 Mount - 12Vdc, 2A
• Currently Canon 5D MkII which is battery powered, but moving to Atik 383L+ - 12Vdc, 2A
• Kendrick DigiFire 7 with 2x 3" and 1x 5" bands - 12Vdc, 3A (8A Max load if I change things)
  • 5" band for scope - 1.2A
  • 3" band for guide scope - 0.8A
  • 3" band for RDF - 0.8A
• 2x 4 port USB2 Hubs - 5Vdc (via 12 => 5Vdc transformer), 4A total max
  • Atik Cam (data only)
  • SX Lodestar (data & power)
  • SX Filter Wheel (data & power)
  • EQDir (data only)
  • Game Pad (data & power)
  • TEMPerHUM (data & power)
  • GPS Module (data & power)

At the laptop (which my be outside or may be inside tent or wooden pod) I also have the following:

• USB SSD Drive (Powered by laptop USB2 port)
• Lakeside Astro Focuser Control unit - 12Vdc, 1A (Powered by same PSU as scope equipment but connected to laptop USB2 port)
• Repurposed EE router to create wifi network for 5D image transfer (12Vdc, 1.5A, but currently using Wall Wart! to stop trips)

Ignoring the Laptop which needs a 240Vac to 19.5Vdc brick, I have a max load of 17A with an estimated load close to 10-12A from my 13.8Vdc 12A power supply....cutting it a little fine I think.

I was wrong about my current PSU...It is in fact a 12A.....but something kept causing it to shut down, so I'm assuming I'm pulling too many amps?
 

[david_taurus83]

12 minutes ago, MG01 said:

Thanks everyone...I was just looking a the following second-hand Kenwood...https://www.hamradio.co.uk/used-equipment/kenwood-ps-52-used

My peak power draw is something like this: (nicked from a post I made earlier today about general settup)

At the scope I have to accommodate the following:

• NEQ6 Mount - 12Vdc, 2A
• Currently Canon 5D MkII which is battery powered, but moving to Atik 383L+ - 12Vdc, 2A
• Kendrick DigiFire 7 with 2x 3" and 1x 5" bands - 12Vdc, 3A (8A Max load if I change things)
  • 5" band for scope - 1.2A
  • 3" band for guide scope - 0.8A
  • 3" band for RDF - 0.8A
• 2x 4 port USB2 Hubs - 5Vdc (via 12 => 5Vdc transformer), 4A total max
  • Atik Cam (data only)
  • SX Lodestar (data & power)
  • SX Filter Wheel (data & power)
  • EQDir (data only)
  • Game Pad (data & power)
  • TEMPerHUM (data & power)
  • GPS Module (data & power)

At the laptop (which my be outside or may be inside tent or wooden pod) I also have the following:

• USB SSD Drive (Powered by laptop USB2 port)
• Lakeside Astro Focuser Control unit - 12Vdc, 1A (Powered by same PSU as scope equipment but connected to laptop USB2 port)
• Repurposed EE router to create wifi network for 5D image transfer (12Vdc, 1.5A, but currently using Wall Wart! to stop trips)

Ignoring the Laptop which needs a 240Vac to 19.5Vdc brick, I have a max load of 17A with an estimated load close to 10-12A from my 13.8Vdc 12A power supply....cutting it a little fine I think.

I was wrong about my current PSU...It is in fact a 12A.....but something kept causing it to shut down, so I'm assuming I'm pulling too many amps?
 

Are those current draws something you have measured or just taking the figures from manufacturer specs? I'd be very surprised if you were drawing 12 amps.

[Carbon Brush]

Really you need to ignore the amp ratings on the items. They are rarely accurate.
Put an ammeter in the line from the PSU and power items one at a time.
That will give you realistic average (not peak) readings.

Something else to bear in mind is that that electrolytic capcitors in powers supplies (whether switcher or linear) degrade with time.
If your PSU has had more than roughly 1000 hours of power on and delivering load, it is worth looking to replace them.

HTH, David.

[MG01]

1 minute ago, david_taurus83 said:

Are those current draws something you have measured or just taking the figures from manufacturer specs? I'd be very surprised if you were drawing 12 amps.

Just from the specs...so theoretical max?

Does that suggest that maybe there's a fault that's causing the PSU to shut down (with the overload light staying on)?

[Tomatobro]

Looks good to me and the price is reasonable. I prefer the ones that have both volts and amp gauges and voltage output adjustable (like the one that Tomato pictured) but I know that they are becoming rare.  For instance mine is a 30 amp but it rarely is asked for more than 6 amps.

 

Edited November 3, 2022 by Tomatobro
picture added

[markse68]

I think it's a good idea to have a dedicated supply for the camera to keep noise form other items from influencing it?

Mark

[newbie alert]

The 383 likes a higher voltage than 12v supply..

Do a search on the 383 to get the most from a classic sensor

[MG01]

2 hours ago, markse68 said:

I think it's a good idea to have a dedicated supply for the camera to keep noise form other items from influencing it?

Mark

I did wonder about that...if I take a single line up to a distro box at the mount is it possible to filter the supply to the cameras?  I'm afraid I'm not that experienced in electronics and wouldn't really know what to do...

43 minutes ago, newbie alert said:

The 383 likes a higher voltage than 12v supply..

Do a search on the 383 to get the most from a classic sensor

I'm looking at 13.5-14volt supplies as most 12v devices are intended to run off old lead acid batteries which typically deliver 13.8 I believe.

[MG01]

One other thought I had was if bundling all the cables together (12v lines, ethernet and/or USB) is going to cause problems.  Should I make sure they are separated?

I know from installing built in speakers and wiring networks that cables containing power and signal should only cross at 90⁰ and not be run in parallel, but wasn't sure if this was just because of induction from the AC circuit? 

My physics a-level was a looooong time ago I'm afraid!

[gajjer]

I use a sealed lead acid battery and a smart battery charger.

Works for me. It will tolerate short power breaks.

I wouldn't worry too much about running power cables parallel to signal cables.

cheers

gaj

 

[Dark Raven]

23 hours ago, MG01 said:

if bundling all the cables together (12v lines, ethernet and/or USB) is going to cause problems.  Should I make sure they are separated?

Yes, always. Not just in AP equipment but as a general rule. Also, upgrade your data cables. If you have ZWO cameras, bin those flat cables and get proper ones.

[MG01]

2 hours ago, Dark Raven said:

Yes, always. Not just in AP equipment but as a general rule. Also, upgrade your data cables. If you have ZWO cameras, bin those flat cables and get proper ones.

For the most part I use belkin or anker data cables where I can.  But I'm considering usb over ethernet for the longer run since i realised my astro laptop doesn't have USB3 and therefore switching to a USB3 hub won't provide the benefit I'm expecting. 

For power I have a 6mm² flex runnjng from my 13.8vdc source and only use 2cores...I did wonder if I could use one core just to provide power to the imaging camera and the other for everything else.  Would this reduce noise in the dc signal or does the shared ground become the issue?

Previously I have run my power flex and usb (now ethernet) in a shared braided sleeving to help with cable management, but sounds like this should be avoided?  Would it help if I used shielded ethernet cable?  Although I'm not clear on how to terminate the shielding as I think it's only one end...I just don't know which!

Apologies for more questions...its just I tend to find that there's often small details that can have big impacts.

[Dark Raven]

16 hours ago, MG01 said:

Would this reduce noise in the dc signal

Yes, it will. However, this kind of noise, although present, is not your primary noise concern. Far greater noise influence will come from thermal and sky glow. Data / power separation is done (mostly but not exclusively) to mitigate data dropouts or equipment disconnects during (slewing) power spikes.

 

16 hours ago, MG01 said:

Previously I have run my power flex and usb (now ethernet) in a shared braided sleeving to help with cable management, but sounds like this should be avoided?

Yes, at all costs.

16 hours ago, MG01 said:

Would it help if I used shielded ethernet cable?

Yes

16 hours ago, MG01 said:

Although I'm not clear on how to terminate the shielding

How To: Terminate a Shielded Cat6/Cat6A Standard Load Bar RJ45 Connect (truecable.com) or buy readymade shielded cables.

[MG01]

Brilliant thanks!

 

[MG01]

I feel like I'm hopscotching all over the place at the moment...but back to PSUs for now!  @Tomatobro I've found one like yours here which seems reasonable: https://www.hamradiostore.co.uk/product/power-supply-30-amps-variable-voltage-analogue-design/

One question I did have was if a load like the mount which has motors would impart additional noise in the form of voltage ripple that could impact on the CCDs?  Would making two separate cable runs make any difference?  I'm probably doing some overthinking here and if i just run this to a power hub and distribute from there it would be fine.

[Tomatobro]

Don't forget that the camera's front end electronics has filters built in so you are as you say "overthinking" it.

I have two power cable runs from the power supply. One goes to the mount and powers a NUC pc, fans, SQM unit, an audio monitor and a ZWO dome camera.

The other power cable from the power supply powers another NUC, The mount itself (EQ8-r), a focuser, filter wheel, ZWO asi1600mm camera. guide scope camera and scope cooling fans.

Also powers a USB 3.0 4 port hub (Startools industrial type).

Hope this helps

Edited November 10, 2022 by Tomatobro
more info

[MG01]

1 hour ago, Tomatobro said:

I have two power cable runs from the power supply. One goes to the mount and powers a NUC pc, fans, SQM unit, an audio monitor and a ZWO dome camera.

Are the two cables just to increase the effective cross-sectional area of the conductor (for the given total load) then?  ie to reduce voltage drop?

[Tomatobro]

having three sets of power cables clearly does help with voltage drop but that is not the intention. The one set with the black braid from the cigar plug goes to the "pier" NUC and allows me to unplug if not required. The doubled up cable set has one pair going underfloor to the "Dome" NUC and the other goes underfloor up the pier to the USB 4 port hub, camera cooler and other stuff.

I do have a led voltmeter mounted on the pier which allows me an "at a glance" check on the system voltage and allows me to tweak the output from the power supply to compensate for different setups on the mount. This because from time to time I change what's on the mount and the loads they present change.

Not really necessary but as a retired technical manager old habits die hard.