December 9, 2014 at 3:14 am #34933
Love the OpenSprinkler! For some reason my expansion board suffered a meltdown out of the blue. (Main unit still fine.) It would be real nice if the design was such that the boards had protection against shorts or other electrical risks (both on power input or control output sides). I’d rather replace a fuse than a whole board. Might not be as simple as that but I will leave the details to the experts. Furthermore a companion device I would love to be able to buy is a manual override board with led indicators. Central to this would be a switch with 3 positions: (1) OpenSprinkler Control, (2) OFF, (3) Manual ON with perhaps (for example) orange/green, Red and Yellow LEDs respectively indicating switch State. So if the OpenSprinkler is ever out of action for some reason (eg my meltdown), I would still have a manual way of operating all valves. (Perhaps the output protection could be built into this board?)December 9, 2014 at 1:54 pm #34934
Would one of these work for you? there are no indicator lights, but it would provide DC fusing.
for blown fuse indication you could use these.
Bill – AB6ORDecember 9, 2014 at 3:28 pm #34936
Thanks William. AliExpress have a similar box.
(Like the smartglow fuses.)
I shall order a fuse block. Still would suggest that a manual override switch unit (with over-current protection & Led indicators) would be a nice additional box.December 9, 2014 at 5:32 pm #34937
@mike1: interesting thought to add a manual override switch unit. I think it’s suitable for a DIY modification, but I don’t see a high demand for this because the main purpose of OpenSprinkler is web-based control.December 9, 2014 at 5:55 pm #34942
Fair call as long as the main unit is never down. So to ensure that what about using opto-isolators &/or fuses to prevent damage to the controller circuitry? I may not be suggesting the right solution as electronics is not my thing but you get the intention. I feel quite exposed as a failure of the system while I am on holiday may have very costly consequences. I have just had such a failure so I have an interest in making it fool proof. Whilst I try not to be that fool, even a spade thru the control wiring could produce such shorts for example. Want to make it when customers do get it wrong or an unexpected environmental event occurs, nothing dies.December 9, 2014 at 6:07 pm #34944
Actually OpenSprinkler already has two built-in fuses: one connected in series with the 24VAC common wire protecting solenoid shorting, and one protecting the +5V line. Also, there are 10 bidirectional TVS (or MOV in DIY kits) to protect the circuit from transient high voltages.
I did think a lot about adding opto-isolators, and decided not to adopt them for the moment, because the opto-isolator is bulky, expensive, and in the event of shorting it has the same risk of leaving the solenoid open. It does, however, isolate the microcontroller so the microcontroller will not be damaged.
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