I have some doubts deciding the power supply in a given system. The entire system is powered up using 12VDC power supply. The system has a small microcontroller unit, some relay and 12V LED panel. To decide the required capacity of the 12v supply, I simply add consumption of each unit.
I have a relay with me with a coil resistance of about 260 ohm. This gives me the current drawn as about 46 mA. The system has four relays and as such the consumption of the relay is approx 200 mA. I do not have data of LED panel but let us assume that it has a consumption of max 100 mA. The microcontroller board consumption is very minimal. It has a 7805 mounted on it and thus operates on 5V. Now say if the power supply provided is 12vdc/1A. What implications it has on 7805. (Should I worry about the dissipation here or since at output of 7805 there is not much load connected, I should be fine)
If I were to find out whether the output of 12vdc supply varies according to the requirement, what parameters should I look out at?