I am looking to control 8 sets of 13 bulbs using the arduino. I am confident with the coding of this and am planning to use relays to switch on and off each set of 13 bulbs.
I am trying to work out the best way of powering the sets of 13 bulbs. The bulbs are 3.5 with a current of 300mA.
Would it be better to power each set of 13 in parallel or in series? And for parallel/series what sort of power supply, and current are needed? Remembering that I also need to power and switch 8 sets of these bulbs.
13 is a prime number.
So it's not possible to make two, three, or four strings with equal numbers of lightbulbs.
One single string is risky. When one bulb blows (they do!), the whole string is out.
Can you change your set to 12 or 16.
The whole setup will use ~110watt, not counting losses.
12volt/10A supplies are common/cheap (ebay).
Four 3.5volt bulbs in series would be perfect on a 12volt supply.
Brightness is slightly down at 3volt/bulb, but lifetime is a lot longer.
Look at the date. This is 2015. Why would you use incandescent globes?
"Warm White" LEDs approximate the colour of an incandescent globe if that concerns you. If you also want slow fade, you can emulate that in software (software PWM). The cost is much the same and you do not have to find sockets for them.
A TPIC6A595 should be able to drive strings of 5 parallel sets of 3 in series from 12V (with series resistors for each set of 3 or 1).
