It’s an often asked question when the subject of system design arises and the answer becomes self evident after the first failure – the dollars saved by using poor quality (read “cheap”) power supplies is more than completely lost when they have to be prematurely replaced.
It’s always good to perform some basic power calculations before specifying or purchasing a suitable power supply (or power supplies) for your project.
Seems simple enough – Once you’ve decided on the operational voltage, just take the current draw of each device that needs to be powered and add them together.
So you have a number of devices (cameras, locks, detectors, etc) that you need to terminate and power up – you could just connect them all to the same set of terminals on your power supply or (if there were too many cables to fit in the terminals) connect up using a piece of terminal strip and just parallel them all – that would be a bit messy and time consuming, but would probably work.
Most CCTV cameras on the market offer 12Vdc or 24Vac operation (they are usually fitted with a small switch or jumper to swap between voltages).
So, AC or DC – which one and why ?