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Clean power for a cooled camera?

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5 replies to this topic

#1 t-ara-fan

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Posted 16 September 2019 - 06:28 PM

I run my ASI071MC Pro from a CUI 12V 5A power supply.  The brick kind, with a switching power supply inside.  So the switcher must make some noise.

 

I also run my USB hub and homebrew dew heater PWM controller from this supply. And sometimes my Mach1GTO, although sometimes the Mach1 has its own Pyramid 13.8V 5A supply.

 

I was thinking - would a LINEAR power supply (like the PR7 here) be better? Less noise, can't hurt right?

 

No doubt the ASI071 runs its cooler with an internal PWM, so it is probably designed to minimize and handle whatever noise that generates.  But what about noise from my mount, and the dew heater?  Am I getting a couple of bits of noise into my camera? 

 

Or maybe one power supply for the camera, and a separate one for the dew heater, USB hub, etc. 

 

 

 

 



#2 hoxca

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Posted 16 September 2019 - 07:08 PM

On my side, i separate the camera from other hardware.

My main focus is to avoid the dew heater which is a known source of noise in power lines.

 

Yes, i use a brick kind switching power supply also.

One for the avalon, one for the focus controller + due heater and another for the camera.



#3 Jim Waters

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Posted 16 September 2019 - 07:19 PM

Do filtering capacitors provide any protection?



#4 rkinnett

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Posted 16 September 2019 - 08:17 PM

The cooler itself is surely robust to power supply noise, and I don't believe cooler power noise affects image noise.  The cooler circuit is electrically isolated from the imaging sensor and interface boards.  They share a common ground and that's it.  If there is any literature or empirical evidence suggesting otherwise I would love to be educated on it.


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#5 gilbertgrape87

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Posted 16 September 2019 - 08:49 PM

I don't have any literature saying one way or another, but I would be extremely disappointed in ZWO if they were controlling the cooler with PWM. PWM is an extremely inefficient way of regulating a peltier cooler.

Since it's most likely linearly controlled, I think that it would be relatively impervious to any minor degree of ripple that might be passed on to the chip.

On the recommendation side of things, I use this power supply at home:

https://www.amazon.c...op_mob_ap_share

It's expensive, but it self regulates to 13.8v with very fast response. I never see any serious droop issues under high demand (dew heaters, full cooling, slewing), and I just hooked an oscilloscope up to it the other day for something unrelated and it was the butteriest smooth DC signal. It's pretty expensive but I wouldn't hesitate to buy it again.

#6 t-ara-fan

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Posted 17 September 2019 - 12:51 AM

Do filtering capacitors provide any protection?

They will, depending on their size and physical makeup.  My PWM is a $10 unit from Amazon.  So I suspect it is a basic as possible and yet still work.

 

I suspect the dew controller would be the noisiest thing, I am tempted to run dedicated power for it, and put a choke on the input so the noise doesn't go back down its powerline and radiate to other power lines. 




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