We're planning an event with a 30-50 free-standing Arduino's (one driven by a PC). Each Arduino will also be powering some electronics, e.g. bunch of LEDs, so could be drawing 300mA+
I'd like some way to power them, which also enables us to connect and disconnect each one to the system.
I thought of modifying a PC power supply, but that would be a relatively monolithic solution, and we might want to reorganise the Arduino's into separate groups, and an approach that scales nicely would be great.
Has anyone tried using a lot of USB chargers? They are very low-cost (under 1 GBP), useful beyond the event, and easy to set up (with enough power strips :-)).
Any comments or alternative suggestions? (I tried googling this forum, but didn't spot anything, so sorry if this is already answered.)
Has anyone tried using a lot of USB chargers? They are very low-cost (under 1 GBP), useful beyond the event, and easy to set up (with enough power strips ).
I've used a cell phone charger that worked well. It was rated as 5.1vdc (regulated) and around 500ma I think. What I did was hack off the chargers plug and wired it to a USB device cable. That way I could just plug it into the Arduino's USB connector and it would power the board. The advantage of using that connector is that the on board USB thermofuse is still able to protect the supply and the normal auto-voltage switching still works if you plug an external power source into the Arduino external power plug.
30 to 50 wal-warts sound like a bit much. Are you going to have 30+ outlets available at the event. A couple of cheap PC PSUs would be a better solution IMO. Off of just one of the Molex connectors you could easily run 5 or 6 arduinos. Its just a matter of doing some wiring. You can have arduinos running off both the 5V and 12V lines of each molex.
This supply will do 40A you should be able to do 120 devices.
For 30+ units I would use terminal blocks to create a bus to
the individual power outputs. Also since you will have one supply
that can deliver a lot of current to an individual board I would
add a fuse to each connection.
The meanwells are pretty good and are available in most parts through distributers like RS components.
The only thing is that switchmode might be a problem because of noise and harmonics so a linear supply would be ideal but a more expensive and its going to get hot and therefore be bigger. You would probably have to design your own one from scratch, using a linear regulator with pass transistors.
Thanks to everyone. You've helped me to focus on what we need. I'm going to try a compromise on the suggestions.
I'm going to do an experiment, and get an RS 15W-25W, 5V switched mode power supply. Then make an 'octopus' cable to 'fan-out' to, say, 8 Arduino's. If this works okay, "rinse and repeat" for 5 more.
This is pretty low-cost, can scale, and overall no single point of failure. It lets us reconfigure the Arduino's, and avoids a lot of power strips.
Thanks again everyone, this has been very helpful.
GB-)
TchnclFl thanks for the suggestion, but I am avoiding the Goldmine electronics products for a few reasons:
I live in the UK, Goldmine don't publish their postal charges. If I'm unlucky, I'll end up paying $20 to the Royal Mail just to collect tax on the postage costs from the USA. I hate this, it drives me crazy.
I'd prefer something a bit safer, i.e. something in a case. This will be in a public place, so the supply needs to be reasonably safe. Also I do teaching and workshops, so I like solutions which I'm happy to recommend to other folks, and I'd feel nervous about folks using that.
After thinking about what we need, I feel I want something which lets us move some of the Arduino's to a different part of the room, and to avoid a single point of failure. So several power-sources, but not too many to avoid power-strip hell, is my current favourite.
Again, thanks for the suggestion. This thread may also be useful for other folks with slightly different constraints, so please keep the ideas coming.