New project: Power supplies for video cameras

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
I have five security cameras, all of which are powered from individual wall warts. 12 VDC SMPS; 1 A each. The warts take up so much space that I can only plug three into a power strip. I have to run two strips to plug in all five cameras, the DVR and the monitor.

I have a 12 VDC SMPS; 5 A. When I connect all five cameras to this supply the voltage remains at 12.2 volts. A single camera wall wart is running 12.4 volts w/out load and 12.2 volts loaded. So my 5A supply is doing the job.

The issue is that when all five cameras are plugged into the same source (2 or more) I get shadow lines across the screen. I contacted the manufacturer and they say the cameras are so sensitive that they each need their own supply. OK, if I have to - I can continue to run two power strips. But I'd LIKE to run just the one and free up plug space.

New project: Build a supply that is capable of delivering 12 volts at approximately 1 amp per output, 5 outputs (possibly as many as 8) with each output isolated from the others.

I have no clue where to begin. Wondering if I should go old school power supply; transformer, rectifiers, filters and regulators. I'd hate to build all that and find out the cameras still do the same thing. Maybe 5 (to 8) LM7812s each with its own filter stages. Any other ideas out there ? ? ?
 

mvas

Joined Jun 19, 2017
538
Try some inexpensive solutions?
Add a Ceramic 0.1 uf cap and/or a low ESR 10 UF cap at the +12 Volt output were the 5 cameras attach
and / or a ferrite bead / choke in each power line.
 
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Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
@mvas Good suggestion. I'll have to see if I can scrounge up some chokes. What's your opinion: Can I use a dual choke from an old power supply?
 

crutschow

Joined Mar 14, 2008
23,500
You may be seeing some sort of ground loop effect with the grounds common, which would mean that all the supplies need to have isolated grounds.
Just buy a larger power strip like one of these 12 outlet units.
It's a lot cheaper and easier.
 

dl324

Joined Mar 30, 2015
9,121
I contacted the manufacturer and they say the cameras are so sensitive that they each need their own supply.
The next time you're in the market, buy better cameras. I'm running 6 cameras and the recording box from the same 12V adapter.
 

AnalogKid

Joined Aug 1, 2013
8,138
Following post #2, either
a) open up the camera; or
b) make a very short male-female powercable jumper, and

either way, add filter capacitors as close as possible to the camera electronics.

ak
 

Yaakov

Joined Jan 27, 2019
1,601
The issue is that when all five cameras are plugged into the same source (2 or more) I get shadow lines across the screen. I contacted the manufacturer and they say the cameras are so sensitive that they each need their own supply.
"Sensitive"? I'd wager more like "noisy". Put two cameras on, filter one (caps, ferrites) and see how it looks.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
Following post #2, either
a) open up the camera; or
b) make a very short male-female powercable jumper, and

either way, add filter capacitors as close as possible to the camera electronics.

ak
Cameras are brand new and under warranty. Opening them would likely void that warranty. As for putting caps as close to the cameras as possible, the cables are 100 feet.

@crutschow Burglars can't shut power off without removing the meter. But by then they've been seen and recorded. As for power failures, they're not common, but within the last month we had one that lasted several hours. It does happen. You recommended bigger power strips. That's probably the way to go. It was only that I had these power supplies and would like to put them to good use. Unfortunately with all cameras on a single supply I get those annoying shade lines in all the videos.

@Yaakov Just before the split to all cameras I put a 1000 µF cap in parallel with a .33µF ceramic. I can power one camera. Any camera and not get those lines. But as soon as I plug a second camera in - the lines return. They're not bad, just annoying. And I've scoped the outputs of both the original PS's and the single big PS. I get the same switching noise at a very high frequency. The AC ripple is so small that my scope can't segregate a single wave, so I can't tell what frequency the SMPS is operating at. But I have to crank up the speed quite high on my scope just to see the images. And the P-P ripple is less than 0.05 volts. Hence, the reason for the filter caps. Maybe I selected the wrong values - I'm certainly not an expert on cap choices.
 

Yaakov

Joined Jan 27, 2019
1,601
@Yaakov Just before the split to all cameras I put a 1000 µF cap in parallel with a .33µF ceramic. I can power one camera. Any camera and not get those lines. But as soon as I plug a second camera in - the lines return. They're not bad, just annoying. And I've scoped the outputs of both the original PS's and the single big PS. I get the same switching noise at a very high frequency. The AC ripple is so small that my scope can't segregate a single wave, so I can't tell what frequency the SMPS is operating at. But I have to crank up the speed quite high on my scope just to see the images. And the P-P ripple is less than 0.05 volts. Hence, the reason for the filter caps. Maybe I selected the wrong values - I'm certainly not an expert on cap choices.
I don't think it is PS noise, I think it is high frequency noise from the cameras. Bypassing one of them at the power input to the camera, not at the output of the PS, I expect, would mitigate the noise. You could do it at the connector.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
@Yaakov I could try building a filter that can be plugged in at the camera, however, all the connections have already been sealed against weather. I would likely spend about 20 to 30 minutes at each camera just to test out the filtering. Then there'd be all that re-sealing. Plus, having the extra wiring at the camera - - - I've gone to great lengths to make it as neat as possible. Don't want a rats nest hanging under the eves. I'd rather just use the five supplies individually.

I suppose there's one good feature to having multiple supplies - if one fails I lose one camera. Whereas if the PS for ALL cameras fail - I lose all cameras. Now that I think of it - it may be a better idea NOT to have all cameras on a single supply. If someone were to reach the wiring, difficult as that would be, shorting out one camera could take all cameras out all at once. Maybe individual supplies is the way to go.
 

Yaakov

Joined Jan 27, 2019
1,601
@Yaakov I could try building a filter that can be plugged in at the camera, however, all the connections have already been sealed against weather. I would likely spend about 20 to 30 minutes at each camera just to test out the filtering. Then there'd be all that re-sealing. Plus, having the extra wiring at the camera - - - I've gone to great lengths to make it as neat as possible. Don't want a rats nest hanging under the eves. I'd rather just use the five supplies individually.

I suppose there's one good feature to having multiple supplies - if one fails I lose one camera. Whereas if the PS for ALL cameras fail - I lose all cameras. Now that I think of it - it may be a better idea NOT to have all cameras on a single supply. If someone were to reach the wiring, difficult as that would be, shorting out one camera could take all cameras out all at once. Maybe individual supplies is the way to go.
OK, then alternatively, you could place the filtering close to the input to the power run but not common, and with a very low impedance path to ground very close by. You only need to test on one, of course.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
Do the lines move?
Yes. They shimmer up and down. It's not like the old school camera filming a monitor. Let me throw the big supply on and use my cell phone to shoot a short video. I'll have to upload it to YouTube so I can post it. Will be a while before I do that.

[edit] Actually I should be able to backup the video to a thumb drive. We'll see.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
Well for those interested - I've given up on fixing the problem. Instead I went with Crutschow's advice to just get a bigger surge protector outlet. 12 plugs, six spaced very wide and apart, great for the camera PS's. So another problem solved. Thanks all.
 

Yaakov

Joined Jan 27, 2019
1,601
Well for those interested - I've given up on fixing the problem. Instead I went with Crutschow's advice to just get a bigger surge protector outlet. 12 plugs, six spaced very wide and apart, great for the camera PS's. So another problem solved. Thanks all.
A practical if vicariously unsatisfying solution. Of course we’d have preferred you do all the hard work we suggested knowing we’d not have to do it ourselves!
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
3,643
Yeah, well from one disaster to the next. The dishwasher just decided to NOT work. Time for a new thread. GEEZ! Another thread. "(

Fortunately I still have the old control board. Removed it because it was having to be cycled for power before it would respond. The new CB has been working fine for a good four years but now refuses to do anything. I've already checked the on-board fuses and the thermal switch. All appear to be good. So it's time to toss the old CB in and see what happens. I MAY just be on my way to the appliance store. I have power to the control board. The only other possibility is the control panel (the buttons). Well, watch for a new thread if you wish.
 
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