Powering the 460EXm issue

[stormlv]

Hi again,
After posting the first light photos that I got from my camera, I'd also like to share with you a problem that I had with the 460EX.

In order to power it from AC, I bought an AC adapter (12V 5A) and tried using it.

Camera works fine, but the problem is that I get a noise pattern on my images which should not be there.
The noise appears as vertical segments that seem to scroll across the image.
This is very apparent when you're taking short exposures.

If I power the camera from my Skywatcher power pack, I don't get this type of noise.

I have also tried a different adapter (same model) and I get the same noise.

Anyone else experienced this problem?

V

[chrisjbaileyuk]

I have found the same with both my 460 and 383. Cheap switched mode power supplies just dont cut it. I invested in a much heavier duty (12 amp) Emerson regulated supply and it solved the problem. I have also found that the streaking is worse when the cooler is working hard so I have cut back on the cooling a little. The 460 is well controlled at 0c and I run the 383 at -15c.

[stormlv]

Thank you for your reply!
It sure does make sense. I will try and see what other power supplies I could buy.
It would also be nice if we'd have a warning on those sort of things...
Best,
Vlad

[stormlv]

Btw, could you also post the model of the PS that you bought?

[topboxman]

Ever thought of using deep cycle marine battery? The voltage is usually over 12.5V and much cleaner than any switching power supply.

I get enough brownouts from my house that I got fed up so I got deep cycle marine battery and mount it inside a plastic battery box. The battery is stored in my garage and always charged/maintained by a battery charger. I've had it for over three years and still running strong. I bought the battery and battery box from Wal-Mart.

See pictures of my battery setup at:

http://tinyurl.com/7w2trn4

See next two pictures as well.

Peter

[jcm]

I use the Maplins regulated power supplies - no problem using the 460EX
on the 5A one.

John

[stormlv]

@topboxman
Well, I already have a power pack that lasts for about 4hours... The idea is that I should be able to use an AC adaptor either way. I didn't think the camera was so sensitive, or that it does not filter anything from the input current.

@jcm
Is this the one you are using?
http://www.maplin.co.uk/12vdc-5a-power-supply-with-2.1mm-tip-513519
If so, mine look exactly the same and have the same power ratings, but still I get this noise in my images.
Did you try and take darks of a few seconds, with the camera powered from the power supply and then from the power pack and see that indeed there is no difference?

[topboxman]

Have you measured the voltage at the camera's power connector when connected to power supply? You can get a power splitter to measure the voltage. Or make your own power splitter. This is a sample power splitter:

http://www.creativelightings.com/Coax-Barrel-Plug-Splitter-2-1mm-by-5-5mm-18-Inch-p/cl-pc2.1-4way-splt.htm?gclid=COT7uNnVv7ICFad7Qgod-h0AEA&click=2

Peter

[chrisjbaileyuk]

I'm not sure its a question of voltage, more that the cheap switched mode ones dont give a very clean DC current. I got a decent Emerson Network Power one from Mouser.

[topboxman]

That is true. I am just trying to do process of elimination. Measure the voltage with and without load and if it drops too much, then the power supply may not be good quality even though it may be rated at high current. You could use a high frequency oscilloscope to measure or examine the noise frequency and amplitude. The higher the noise amplitude the worse it is.

Peter

[stormlv]

I was also thinking of an oscilloscope, but I personally don't own one.
I might try and see if I find one at work and check just for fun...

[jcm]

@jcm
Is this the one you are using?
http://www.maplin.co.uk/12vdc-5a-power-supply-with-2.1mm-tip-513519
If so, mine look exactly the same and have the same power ratings, but still I get this noise in my images.
Did you try and take darks of a few seconds, with the camera powered from the power supply and then from the power pack and see that indeed there is no difference?

No , the one I use is a bench power supply :-

http://www.maplin.co.uk/13.8v-regulated-mains-power-units-231

Its the 22Y - 5A model

John

[topboxman]

That explains why this power supply works so well. It's outputing 13.8V which should be fine.

Peter

[stormlv]

@topboxman
That actually doesn't explain anything. I have been running the camera until my powerpack was almost drained and checked the voltage afterwards. The battery was outputting around 10.5V and still I didn't get any of the things that I had previously described.

Nor do I think that the problem lies in how much current the power supply must output. 5A should be more than enough for the tiny peltier chip that's actually cooling the camera.

I think the problem lies in the fact that the power supply that I was using has quite a bit of ripple and noise.

I just ordered a new power supply of a much higher quality and will get back to you when I get it

Btw, John, isn't 13.8V a bit too much since it's at the top limit for powering the camera?

[topboxman]

I am glad to hear that the camera works at well below 12V using battery. It's obvious that your power supply is not good quality.

Let us know if the new power supply works better.

Peter