How reliable are Arduinos??

I want to run 4 Peristaltic pumps off an arudino. They are 6 volts and low watts.

I want to use them to dose my aquarium. (1 for calcium, 1 for magnesium, 1 for carbonate and one for minerals)

Could i just connect them to four channels directly??

Then devide 24 hours into seconds (86400 / 4 = 21600)

Then tell the program to turn pump 1 on for 5 seconds (5000) wait 20000000 pump 2 on for 5 seconds (5000) wait 20000000 pump 3 on for 5 seconds (5000) wait 20000000 pump 4 on for 5 seconds (5000) wait 20000000

or is that too simple??

I know it would be simple to do that with leds... But is it reliable to leave them on 24/7

If it were to pump the whole bottle in at once it would be quite bad. :)

Thank you for reading.

Arduino boards are quite reliable, mostly because of the small number of components used for the basic board. I've had a 5x5x5 led cube running continuously for over 18 months I think with only interruptions due to a few house power outages.

Lefty

Use a second arduino to monitor the output of the main one. If there are any errors have the monitoring one shut the master down. If the monitoring one fails (use a watch-dog function to check it's operating) then shut down the master since it is no longer monitored. Such techniques are common in industrial PLCs - many using 3 in combination where they vote on a 2-out-of-3 basis.

I would use a battery backed real time clock chip, such as DS1307.
http://www.dipmicro.com/store/DS1307N

Available as an assembled item with chip, battery holder, crystal, I2C pullup resistors here for example

Check the time periodically and see if it’s time to pump some in.
Then if you have a temporary power outage, you will still pump in at the correct time assuming power is back on.

CrossRoads: I would use a battery backed real time clock chip, such as DS1307. http://www.dipmicro.com/store/DS1307N

Available as an assembled item with chip, battery holder, crystal, I2C pullup resistors here for example https://www.adafruit.com/category/products/255

Check the time periodically and see if it's time to pump some in. Then if you have a temporary power outage, you will still pump in at the correct time assuming power is back on.

And if the prospect of power outages worry you, add a rechargable battery and appropriate charging circuit.

Then surround it with a faraday cage, inside NEMA 6 or 6P or higher rated enclosure, behind 0.5 in. bullet-proof lexan shields. Then it should be fairly reliable... ;)

Then surround it with a faraday cage, inside NEMA 6 or 6P or higher rated enclosure, behind 0.5 in. bullet-proof lexan shields. Then it should be fairly reliable...

No help for internal cock ups though :) although I guess that would stop the magic smoke from getting out.


Rob

Graynomad:

Then surround it with a faraday cage, inside NEMA 6 or 6P or higher rated enclosure, behind 0.5 in. bullet-proof lexan shields. Then it should be fairly reliable...

No help for internal cock ups though :) although I guess that would stop the magic smoke from getting out.

Well you also need the backup generator in case you have extended power outages. And of course an adequate supply of gasoline/diesel/natural gas/nuclear. FWIW, it takes about 10 gallons of gas to power our generator for 24 hours, and it can power about 1/2 of the house.

No I think he needs a tidal generator for power and forget the plastic's he needs to find a salt cave at least a mile below sea level to prevent damage from cosmic rays possibly a focused mirror and a bunch of Seebeck junctions at the point of focus might make enough power to keep the array aligned and have enough excess for a main battery and a backup battery as well...

Doc

For a permanent installation I would favour using something like the Arduino Pro or Mini Pro or Nano - firstly they are cheaper, but more importantly there is no IC socket (a possible source of mechanical unreliability) and no aluminium electroytics (limited lifetime). Expect good reliability if it runs cool from a well-behaved power supply - electronics are amazing reliable if not overstressed - most failures in the field are in high voltage circuits, or components that run hot, or Al electrolytics getting old and dry.

Actually looking at the Arduino Pro I would probably desolder the power selection switch and hardwire this (mechanical switches are a source of unreliability as the contacts gradually tarnish and corrode).

Then tell the program to turn pump 1 on for 5 seconds (5000) wait 20000000 pump 2 on for 5 seconds (5000) wait 20000000 pump 3 on for 5 seconds (5000) wait 20000000 pump 4 on for 5 seconds (5000) wait 20000000

Basically, this will work.

But if the arduino fails for some reason (for example: power outage or an EMP due to nuclear missles (to stay on the topic here), ...) it will add an unplanned dosis to your aquarium, which can harm your fishes if this happens more often.

To prevent this, you could write your sketch to wait 20000000 [u]first[/u] and then run the pumps for 5 seconds. So if the arduino fails and reboots, it will skip a dosis instead of adding one.

this guy seems to think so. http://arduino-aquarium.blogspot.com/ as well as a ton of other people on the interwebs. Not really the answer to your question but maybe some reinforcement that its ok. i'm no expert but I beat the crap out of mine and they all still work. In fact I have 3 arduinos and never had one go bad in any way. I get the real ones from italy. Because, like, its pretty much a ferrari right? Because thats how i roll XD