CCTV cameras: single PSU or individual PSUs ?

[Dannyx]

Re: CCTV cameras: single PSU or individual PSUs ?

Yeah, well it's no big deal - good ideas are always welcome and the best one are those which come at random and completely unrelated

I'm always on the lookout for a good project, PSUs included, so I never pass up a good dumpster dive, although our joint doesn't seem to be throwing out stuff all that often and most of it is useless anyway. We do have some servers around, so the possibility of coming across a PSU like that is possible, but just barely, because it's unlikely to still be functional at that point...hence why it's in the dumpster behind the building, where I usually like to stroll and "window-shop"

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

AH, yeah, honestly this whole thing just stemmed from the thought that you could do a pretty simple active/passive failover with a relay and a few support components. ^.^; I didn't even really have an intention of drawing up a schematic, but people were asking some questions about it. (I certainly didn't intend on Hijacking Danny's thread.. SORRY DANNY!) Frankly, under any normal circumstances, I would probably just use oring shotky diodes on two supplies or use a couple of mosfet's as a stand in's. If I needed fancier I'd just go with mosfet's and a purpose-made IC with overcurrent/undercurrent and low/high voltage cuttoffs...

[eccerr0r]

Re: CCTV cameras: single PSU or individual PSUs ?

Ah... it would be more interesting when the supplies are symmetric to each other, which is what redundant server PSUs generally are.

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Ah.. It posted my post twice. :/ also, i have been messaging using my phone.. It seems that it has auto corrected some stuff. :| oh, also, i didn't notice that the schemaic I posted had 16v on one of the supply voltages... That should be 12v..

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Okay! I drew up the schematic in everycircuit to try to explain this a little bit better. there are some limitations to the layout capabilities of everycircuit so it's a bit of a mess.
https://netorgft4619478-my.sharepoin...RsPjNMNzawY1hw

For an explanation of how the circuit works you can watch this video I made.

https://youtu.be/cxZXUr33Ic8

[Curious.George]

Re: CCTV cameras: single PSU or individual PSUs ?

(Still have a decent Bench supply, but meh.)

I have a rack-mountable triple supply that is digitally programmable. Its handy when I'm dealing with something "unknown" as I can type in voltage set and max current limit -- then monitor the voltage and current without having to drag out a meter to see if the "unknown" is, perhaps, toast!

Most of the time though, the PSU's I deal with are just from old pc's. Because I'm "the boss" I worry that taking server type hardware home would set a bad example. (We often sell our old server stuff to reseller types.)

We break-down servers and other bits of kit -- power supplies just get tossed into a Gaylord. So, fish through the Gaylord for something that "looks about right" (chances are, it's perfectly functional).

Biggest problem is dealing with the edge connectors that are commonplace on enterprise kit. Solution is just to solder directly to the fingers. Attached pic of the supplies I use to test powerchairs -- "(BIG) battery eliminators"). Anderson connectors are common on the chairs (high current rating, ease of connect/disconnect)

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

That would depend on what the latch circuit is. if you're talking about the simple circuit with the relay then just turning on the primary PSU would click the relay on. Since the relay on. If the primary psu turned off, the so would the relay, switching the power to the secondary.. in terms of what could be used as a latch, you could do this with several things. You could do this with a relay and A switch for instance. ( press the switch to turn on the relay. The relay then powers itself through the output.) Give me a sec and I'll do a quick schematic. I this this could work.. You know. As a manual reset sort of deal. Haha

[Dannyx]

Re: CCTV cameras: single PSU or individual PSUs ?

ATX PSUs? Reliable? Ever looked at this website?

Yeah, like I said, I'm sure there ARE good ATX supplies, but only high-end ones. I'd dare to say my Corsair HX1200i is amongst them, since I can't imagine that thing would fail on me like a Deer, a Premier or a Delux, would it ?

[budm]

Re: CCTV cameras: single PSU or individual PSUs ?

But how about "How would you deal with initial power on?" as eccerr0r pointed out?
That relay circuit also needs to have hysteresis.

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Ah, I will do so later for sure.

In the simple circuit, I would be relying on something like this circuit (low-tech 12v battery undervoltage protection).


The circuit would be powered by the "primary" psu. If the psu shut off or dropped below a voltage threshhold the relay would turn off and the normally closed position would engage. That would switch the LOAD to the secondary psu.

The problem I see with this though is that the unloaded primary psu might turn back on and we would get flapping. That is why the circuit would need to latch.. But honestly, all of this is just my love of passive tech solutions showing through. lol I thought the idea of the "natural" failover that a relay would do as fun. I think that, like you said, Diode's and Mosfets could do this well.

I think a better solution(than my simple relay solution) would honestly be diode OR logic powering a microcontroller. Then, the microcontroller would sense voltage on both psu's. If the primary's voltage drops below a threshold it would just turn off the relay which would switch things over to the secondary. From there the sky is really the limit on how you'd like to be informormed that the old psu failed. This could be a really fun ESP8266 type project. Have it connect to wireless and send an email alert to a recipient. The nice thing about this would be that you would both have the low ohm/high current capabilities of a relay and the versatility of an mpu.

[eccerr0r]

Re: CCTV cameras: single PSU or individual PSUs ?

How would you deal with initial power on? Draw a circuit?

Normally people do PSU redundancy/failover with diode logic-OR structures, though it has significantly more loss than a relay (though the current flowing for a few CCTV cameras it's not as bad).

That being said, I wonder if the complexity of using MOSFET switches is a better idea.

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Hmm... You know, you could make a super simple failover for a 12v bus by using a relay. So like, you could get 2 of those meanwell supplies and then have the psu's sitting in an active/passive setup. The primary would power the relay and the relay would be set in a normally closed position.. Then if that psu failed, it would cut power to the psu and switch over to the secondary psu.

Kind of a janky hack, but it could be fun. haha I think to do it real proper you'd probably want to power the relay with something like a simple low voltage cuttoff (with latch). That way, if the primary started putting out something like 9v the cut over would be latched and not try to switch back to the primary. (To keep the relay from kicking back on the moment the primary load is lifted and the voltage floats back up to 12v.) This could probably be done with a mosfet, zener, some resistors, some diodes and a relay... that, or just a relay module and a micro controller. (yay for programmable logic.)

[eccerr0r]

Re: CCTV cameras: single PSU or individual PSUs ?

ATX PSUs? Reliable? Ever looked at this website?

[Dannyx]

Re: CCTV cameras: single PSU or individual PSUs ?

I was considering a regular ATX supply for powering my network sh!t, since I'm not sure it's a good idea to have both the network gear and the CCTV stuff on the same supply. Bonus: it's got a 5v output as well, should I need it, but then I thought that's not exactly "high quality", since all I have are a few boxes rescued from the junk pile which I just recapped....unless I spend a lot on a "proper" supply which defeats the whole purpose, since at that point I'm obviously better of getting an off the shelf power supply for far less money than the ATX supply at that. MeanWell seems to be the best maker of SMPSs, not counting ATXs. I think I settled on this LRS-150-12.....

[eccerr0r]

Re: CCTV cameras: single PSU or individual PSUs ?

Speaking of server PSUs and going off topic, I ended up getting one at a hamfest that the seller ended up pitching as nobody wanted. Which sort of makes sense - there was no specific documentation about the PSU on even how to get it to turn on! Seems like it needed I2C or something to turn on, I did not find any !PSON pin.

I ended up putting in my own !PSON wire...

However it still doesn't work all that well, was able to power car headlight bulbs just fine but I know that I'm missing the feedback pins which I still have no clue which one it is... if there is one...

This is because the PSU appears to be single rail (all windings on one transformer), and if the +5 has more resistance than +12, how does one compensate for both without disturbing the other?

Hmm... lots of mysteries still to be solved.

[stj]

Re: CCTV cameras: single PSU or individual PSUs ?

server psu's are in high demand,
car service guys and radio hams among others are buying a lot now.
also fucking a lot because they dont understand how they work and try to push them to 14v based on half-assed utube vids.

because as we all know, everybody with a utube channel is a god who knows exactly what they are doing!!! /sarc.

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Yeah, I use rescue PSU's for all sorts of fun stuff. haha For instance, all the bench lighting on my bench is powered by the 12v from a psu. I also have a few of those little buck converters with the screens mounted around for a quick source of power. (Still have a decent Bench supply, but meh.) Most of the time though, the PSU's I deal with are just from old pc's. Because I'm "the boss" I worry that taking server type hardware home would set a bad example. (We often sell our old server stuff to reseller types.)

[Curious.George]

Re: CCTV cameras: single PSU or individual PSUs ?

I will say that I have had to deal with a fair amount of the "cheap chinese psu" power source for analogue cameras in my Career. (I am a network admin/it systems manager.) From what I have seen, the ones that are going to die tend do so either in the first year or after someone decides to push it too hard by adding in a bunch of extra cameras. (Ie: bumping it's utilization from 40% to 60%.) It seems to me that a lot of them could be decent/are decent but there are also a lot of them that don't have good cooling for their power transistors/mosfets. :/

We're using 12V "bricks" from LCD monitors to power groups of (analog) cameras. If a brick fails, there are plenty more to choose from in the "discards" pile! (don't care what sort of barrel connector it uses as you'll cut that off when repurposing it)

Something I've always wanted to do is to take a few good quality server psu's and then use them as a redundant power backbone, like you would in a server. One of these days I'll grab an old server we are throwing out and do this. For now, I'm using a cheap ebay PSU that I analyzed/"fixed" of it's bad design flaws. (no thermal grease, unmatched mosfets, poor soldering, bad tank capacitors. lol)

I rescued several high-capacity (900-1100W), dual-redundant PSU assemblies (two power supplies in a "card cage", of sorts) from disk arrays -- gobs of 12VDC. I wire them in series and use them to power my electric wheelbarrow (instead of a pair of "car batteries").

Apparently, the RC crowd also uses these sorts of rescues to quick-charge their battery packs (?)

[Retro-Hipster]

Re: CCTV cameras: single PSU or individual PSUs ?

Ah, I haven't been back here in a while! Looks like you have some more interesting conversations going Danny.

I will say that I have had to deal with a fair amount of the "cheap chinese psu" power source for analogue cameras in my Career. (I am a network admin/it systems manager.) From what I have seen, the ones that are going to die tend do so either in the first year or after someone decides to push it too hard by adding in a bunch of extra cameras. (Ie: bumping it's utilization from 40% to 60%.) It seems to me that a lot of them could be decent/are decent but there are also a lot of them that don't have good cooling for their power transistors/mosfets. :/

Something I've always wanted to do is to take a few good quality server psu's and then use them as a redundant power backbone, like you would in a server. One of these days I'll grab an old server we are throwing out and do this. For now, I'm using a cheap ebay PSU that I analyzed/"fixed" of it's bad design flaws. (no thermal grease, unmatched mosfets, poor soldering, bad tank capacitors. lol)

Not that this is economically feasible for almost anyone, but one place I worked for used a 96 port Cisco POE switch (something like a Cisco Catalyst 4506) for all their security cameras. Now that is how it is done. lol They were already using these for the phones since they were a call center. Guess the lead admin wanted to stick with the same gear for security cameras.

One of these days I should make a video about what to check on those ebay PSU's and the things that generally are done poorly.

[Dannyx]

Re: CCTV cameras: single PSU or individual PSUs ?

About that: I'm starting to question how "good" (or rather "decent") those generic PSUs from Ali truly are. I got a 10 amper running the DVR, a small peep-hole camera on the door and a small 7 inch monitor for live view at the moment. I've had it for about an year now and it's been running fine. The only problem is that I get some herring bone patterns on the monitor, which don't show up on the live feed if I access the DVR directly from the app or a PC, so there's something wrong with that analog output there. I haven't yet tried a separate PSU for the monitor itself to see if that changes anything. I believe I've grounded everything properly too (all GNDs together to the GND of the supply and even the case of the DVR), so it could just be the monitor is dodgy - it's a cheap nasty thing I picked up at a flea market....

I think I might actually have to dish out more and go with a MeanWell for my network stuff just to be on the safe side with stuff like ripple, output overshoot and overall life of the thing.....maybe...not sure...