Your CCTV cameras will require reliable 12v power supply to power your camera and heater in enclosure
Your CCTV cameras will require a 12v power supply which are available readily from suppliers such as Maplin or RS Components. Just make sure that its current rating is adequate for the camera and if the power supply is not designed for outdoor use then ensure that only the low voltage output runs outdoors. An in-line fuse on the 12v supply is probably a good idea too.
Housings such as the Genie TP2000 are fitted with a thermostatically controlled heater for dew control. If your housing includes a dew heater we recommend that this runs off a separate 12v power supply. Switching of the thermostat can create electrical noise which may result in false detections.
Having spent a fortune on your camera, lens and enclosure it’s now worth spending a few pounds more to make sure the camera doesn’t turn on during the day. To protect your camera's sensor from direct sunlight the lens iris must be kept closed in daytime hours; this is achieved by simply switching off the power supply to the camera. With no power the iris will close and the sensor is protected from damage.
Ideally controlling the power to the camera should be automated and there is a cheap but effective solution in the form of domestic timers (the sort you use on your table lamps when you go on holiday).
To reduce power overall consumption, a timer can be fitted to the dew heater as well. Dew heaters should be timed to switch on perhaps an hour before the camera so that any accumulated dew is cleared before the camera is made active. It is important to check the operation of your timers and to ensure that they are set correctly otherwise damage to the sensor may occur inadvertently.
One of the problems with domestic timers is that they need constant adjustment for sunrise and sunset times. There are more intelligent ways to control power, and one of these is to use a photocell light switch.
Jim Rowe makes the following suggestion. Buy a couple of photocell light switches. It’s safer and cheaper to work on the 12 Volts DC output of the PSU rather than 240 Volts AC input. Log log on to eBay or Amazon and look for a “12V 10A Auto On Off Photocell Light Switch Photoswitch Light Sensor Switch” or similar. The one in the picture will cost you about £2.45 to £3.
Buy two of these and install them in serial. That means if one fails (so it turns on during the day rather than just at night) then the second one will still protect your camera.
To install two photocell switches in serial, connect up the wires as follows:
At a practical level, you may want to hide your joins and cables in a bit of ducting, so here’s how it might all look when you’ve finished (right image).
Unfortunately, many 12v power supplies do not provide an indicator when they are on and so it is difficult to see at a glance when – or if – your power supplies are delivering power. This usually requires you to squint at the tiny display on the timer and even then you can't be sure. One useful tip from Peter Campbell-Burns is to wire LEDs into the 12v output. Simple LEDs will require a current limiting resistor but Maplin sells 12v panel mount LEDs with an inbuilt resistor making the job much easier. These cost just a couple of pounds each.
If you have, say, two cameras then do you need four power supplies? We have advised against using a single power supply to power both camera and dew heater due to noise spikes from heater switching. However, one UKMON member has been running two cameras off a shared power supply without problem, and a second power supply is shared by two dew heaters. The only word of caution here to ensure that the current rating of the power supplies exceeds the combined loading of any attached devices.