Anyone have any experience of cctv. The cameras keep blacking out! Restore is done unconnecting and reconnecting power supply at camera, jack plug. One 1amp, 12v dc, power supply unit feeds two swann cameras and with just one camera being lost, in the paired units of 8, I am thinking it is a power issue. Great system, easy to use and 4 days recording so not looking to change anything bar the power units to a dedicated cctv psu. My question is, can one have too many amps as the psu I looking at gives 1.65 amps per channel, compared to the existing .5 amp? No amp rating on camera! Existing system is all prewired with 30mtr cables. Another thought I had was the excess cable as that had to be tidied up by means of large loop.
CCTV, workshop security
- Thread starter Housey210
- Start date
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You don't give amps, the load draws the amperage required so providing your power supply is capable of meeting the total demand of the camera's then you will be ok. If there is insufficient power then this leads to volt drop and potentially the system cannot function. It is not good to coil up excess cable.
Long cables supplying the power to cameras cause large voltage drops - I have one run of about 15m to a camera and it needs the power supply set to 15.5 Volts in order for the camera to see the 12 volts that it needs.
G.
G.
Unless you can get larger csa cables, many of the ready made cables supplied with camera kits are too small in wire csa.
Just a caution, there is a potential problem with this if you connect the camera when the PSU is already on. A 12V camera might have an absolute maximum rating of, say 13V (as an example). Anything over that may cause damage.
If you connect a live supply to the camera, the supply is open circuit and sitting at 15.5V, so the input components are overstressed momentarily. This may not cause problems immediately, but may shorten the life of the camera.
That was true with the old style linear power supplies, but I haven't seen one of those new in a couple of decades...
It isn't true with switchmode PSU's however, which have been the default power supplies since the 1990's/2000's- anything with that 100-240v 50/60 hz label is a switchmode and the output is regulated on its output, all of them...
( got 50 years of playing with electronics under my belt, both as a hobbyist and as a job)
If the PSU has that label- its a switchmode...
clogs
just can't decide
to ask.....
I have a workshop around 100m from myhouse...(on my land, upa private road but driving u meet the workshop first) I plan to place a second gate at the entrance to the road just to stop drive thru's but it wont stop wondering tent dwellers.....
So need a full system of camera's, 4 should sufice.....have a 240mins supply close...
but would like a buzzer at home as well as a TV moniter to view whats going on....
there will be a few well placed LED flood lights PIR activated....
any suggestions on a good simple system.....
PS all cameras would be around 5m high with high level wiring.....
thanks.....
oh..would like to do the first fit before the w/shop is complete....hiding wires etc.....
I have a workshop around 100m from myhouse...(on my land, upa private road but driving u meet the workshop first) I plan to place a second gate at the entrance to the road just to stop drive thru's but it wont stop wondering tent dwellers.....
So need a full system of camera's, 4 should sufice.....have a 240mins supply close...
but would like a buzzer at home as well as a TV moniter to view whats going on....
there will be a few well placed LED flood lights PIR activated....
any suggestions on a good simple system.....
PS all cameras would be around 5m high with high level wiring.....
thanks.....
oh..would like to do the first fit before the w/shop is complete....hiding wires etc.....
Superduner
Established Member
I'm about to install a 4 camera HDD based Reolink system for a client using power over ethernet. I'm not using the cables that came with the kit but good quality cat 6. I'm told they should be good for 100 metres which is twice as far as I need.
That removes the need for installing power supplies at the camera locations, which would have been tricky.
That removes the need for installing power supplies at the camera locations, which would have been tricky.
The easiest would be a wired system (4 and 8 camera DVRs are common)- BUT 100m is a long run for the 'premade' cables, you will have voltage drop issues at that range...
I would suggest using just a premade video cable (BNC connectors are the most common), and use a separate heavyduty fig 8 double insulated power cable (4mm) ie the black sheathed fig 8 used in automotive use for the power lines...
You could use the premade stuff with inbuilt power cables, but use that power cable as an alarm switch for the PIRs (many DVRs have a 'alarm' input that triggers the DVR when it is closed, connect the pir output to the DVR alarm input using that undersized inbuilt power cable
If you put the DVR at the shed, you can usually run another hundred meters or two from its HDML output using video repeaters to a monitor or TV with HDML input, and many have an alarm output set of terminals as well that you could use via a cable to activate a piezo buzzer at the house..., alternatively if you have internet at the shed possible, then the DVRs all have the ability to send you an email, some have SMS as well (only in the more expensive ones)
It is possible to do the comms by wifi and just have a local power source- this is what I am installing at my front gate (500m away- far too long for wired lol), a long range wifi link (Unifi LR routers at each end), with a wifi network camera at the gate, and some WIFI triggered relay boards with inputs as well- this will allow a 'doorbell button' at the gate, and the ability to trigger the automatic gate opener and/or floodlamps by wifi- the gate end will be solar powered
Thats a fairly complicated system however with much of it being homebrewed by me, using off the shelf equipement but needs knowledge to assemble the various bits together to make it all work, its not a plug and play' setup... luckily I know a guy good with electronics lol (ie me!!!)
With all due respect, I think you have mis-read what is happening. You are correct there used to unregulated linear supplies, but that's not what I am referring to in this particular case.
The OP has long power leads going to his camera, so to compensate for the voltage drop, they have to increase the supply voltage. It has nothing to do with the difference between a linear supply and a switch mode. You can get linear supplies with excellent regulation, but since they rely on a controlled voltage drop over a linear device(2N3055) they are less efficient than a switch mode.
If you have very long leads, you convert a regulated supply to one with poor regulation, where the output voltage at the ends of the long leads becomes a function of the resistance of the leads and the current.
V(at end of leads)= V (regulated)-Current X lead resistance.
V regulated doesn't change. When the current is zero. The voltage at the end of the leads= regulated output. In the OP's case, 15.5V. This is the important point when you boost a voltage to compensate for line drop and connect the camera to a live supply. The 12V camera will see an input of 15,5V
As soon as the camera starts drawing current, the voltage will drop, but it will be a function of the current, it's become an unregulated supply. The input components will already have seen an overstress condition.
One way to compensate for long leads is by using a sensed power supply. The sensed power supply has 4 wires +V, -V, +Vsense and -Vsense. The sense inputs are very high impedance, essentially it's like having a voltmeter at the end of the leads and a compensation circuit to change the output voltage as the load changes.
Power supplies have line regulation and load regulation. The 100-240V shows the SMPSU have excellent line regulation. Remember the old linear supplies with switch input to change the transformer winding
You could design a universal input linear supply without switching and do all the regulation on the output, but it would have poor efficiency.
Linear supplies are still popular in some areas, they are much lower noise , but lower efficiency (52%!!)
SamG340
Established Member
Yes cable length / voltage drop is a real issue with 12v DC
Even these type of PSU had regulated outputs and are the better choice for audio amplifiers but as Sandyn has said the issues come down to the basics of electrical theory and not the type of PSU. The problem not completely mentioned is that by increasing the voltage at one end to compensate for the volt drop caused by the long cables you are decreasing efficiency and wasting energy. When designing electrical circuits you size the wire so that it can carry the required load current and within a specified volt drop, this means increasing the csa as the length increases upto a point.
Even worse when vehicles used 6 volt electric's and one of the reasons why the national grid use high voltages for transmission.
Thinking about the CCTV then why not use 24 volt camera's as this would halve your problem and solve it.
I am going to dig out my multimeter to establish dc at camera end! Cables now unwound. Cut outs tend to be at night so I guess the infra red has more of an impact on the draw than the camera. Motion sensor mode also switched off. Amps, of what?
Don't forget to have the camera connected and active when you measure the voltage - it'll be interesting to see what it is.
G.
G.
You are assuming that I have little to no knowledge of electronics... you know what they say about assuming something...With all due respect, I think you have mis-read what is happening. You are correct there used to unregulated linear supplies, but that's not what I am referring to in this particular case.
The OP has long power leads going to his camera, so to compensate for the voltage drop, they have to increase the supply voltage. It has nothing to do with the difference between a linear supply and a switch mode. You can get linear supplies with excellent regulation, but since they rely on a controlled voltage drop over a linear device(2N3055) they are less efficient than a switch mode.
If you have very long leads, you convert a regulated supply to one with poor regulation, where the output voltage at the ends of the long leads becomes a function of the resistance of the leads and the current.
V(at end of leads)= V (regulated)-Current X lead resistance.
V regulated doesn't change. When the current is zero. The voltage at the end of the leads= regulated output. In the OP's case, 15.5V. This is the important point when you boost a voltage to compensate for line drop and connect the camera to a live supply. The 12V camera will see an input of 15,5V
As soon as the camera starts drawing current, the voltage will drop, but it will be a function of the current, it's become an unregulated supply. The input components will already have seen an overstress condition.
One way to compensate for long leads is by using a sensed power supply. The sensed power supply has 4 wires +V, -V, +Vsense and -Vsense. The sense inputs are very high impedance, essentially it's like having a voltmeter at the end of the leads and a compensation circuit to change the output voltage as the load changes.
Power supplies have line regulation and load regulation. The 100-240V shows the SMPSU have excellent line regulation. Remember the old linear supplies with switch input to change the transformer winding
You could design a universal input linear supply without switching and do all the regulation on the output, but it would have poor efficiency.
Linear supplies are still popular in some areas, they are much lower noise , but lower efficiency (52%!!)
As for the camera seeing an overvolt condition- well that would only happen if the PSU was overvoltage to begin with-so it is an inappropriate PSU to begin with- it would overvolt under almost all conditions- long leads or not...
Yes professionals will in the appropriate conditions use an 'overvoltage' supply- but they also don't feed it to the camera direct, but use it to feed a local regulator board at the camera (assuming it doesn't incorporate it internally)
(and yes, I did for many years hold a NSW class A/D/E security licence- which is patrol, alarm sales and cctv installation..)
;-)
(I got a lot of electronics experience under my belt- half a centuries worth- working in the mines I both designed and made electronics- including power supplies...)
;-)
12v are common in the 'consumer level' 'el cheapo's- but there are available 5v, 12v, 24v, and 48v ones also available- plus of course the pro's would know to use a higher voltage at the feed end and then use a regulated feed circuit at the camera end...
;-)
You have (depending on the camera in question) up to double the amperage of the camera current drawn... feeding the IR illumination diodes- thus the current is far higher when they are on...
more current = higher voltage drop ie less voltage to power the camera...
(the pros on REALLY long runs- feed that run with a separate high voltage PSU (often double or more its requirements), then add a regulated LV supply at the far end- that way regardless of voltage drop, the camera gets a regulated supply...
ie if it is a 12v camera, then I would use a 24v feed at the DVR/camera feed location, then at the camera end use a 12-24v to 12v converter- that way, regardless of voltage drop, get a stable 12v at the end of the feed, regardless of the varying feed voltage...
(this is why the pro's can do what the average consumer can't- it's all in knowing what to do lol)
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SOME (very few) had regulated outputs most were very basic circuits-and any minor fluctuations on the AC input was reflected on the output...
A 12v switchmode wouldn't be at 15v in the first place- only linear PSU's exhibit this behaviour- a switchmode loaded and unloaded voltages are practically identical- and at the end of a long run, the switchmode would indeed drop- but it would be below (well below in this case) 12v- unless the manufacturer for some bizarre reason provided a PSU that would blow up the camera 'unless plugged into a 100m power lead'...
Unlikely...
Increasing the cable size was indeed the very first thing I mentioned...
"I would suggest using just a premade video cable (BNC connectors are the most common), and use a separate heavyduty fig 8 double insulated power cable (4mm) ie the black sheathed fig 8 used in automotive use for the power lines..."
;-)
(that wire size was chosen to accomodate the 'average consumer grade' CCTV camera's power consumption and a 100m distance between the camera and the PSU (note it is far larger than the power cables in the 'all in one' combination leads- which are usually 1mm^2 or less in size...)
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