3 ms·

Damn, why did I never think to use a leak sensor? I’ve been goofing around with building some unusual devices and messing with relays and io pins and arduino an

Damn, why did I never think to use a leak sensor? I’ve been goofing around with building some unusual devices and messing with relays and io pins and arduino and completely missed this obvious solution. It’s literally a device designed to do exactly what I sometimes need (start an action if a circuit closes) and I just never thought about it even though I know how leak sensors work and that there are ones available. Duh! Stuff like that is why I love HN. Thanks to the author if you’re reading.

shellfishgene 3y ago
Door/window sensors also work and are even smaller than the leak ones. Just replace the reed switch with whatever.
- timemct 3y ago
  Some d/w sensors will even have dry contacts specifically meant for wiring in whatever open/close type thing you'd like to use, like a pressure pad.
- mattmaroon 3y ago
  I didn’t realize there were any that weren’t part of an alarm system/proprietary but it seems the same company makes those too. I guess that would also be a really easy to do the opposite (if it mattered) since a reed switch triggers the action when it opens, but a leak detector when it closes. Or I guess maybe they do both. I am curious why the leak detector is bigger if it’s a simpler device. Basically the same thing but without the reed switch right? Maybe just to make room for more battery since you actually care how big the door sensor is.
  - shellfishgene 3y ago
    Door/window sensors usually send a signal on state change from closed to open or the other way around. I think a leak sensor is more complicated because it needs to detect a somewhat lowered resistance between the contacts, as opposed to the door sensors that will get a fully closed/opened reed switch on activation. Detecting lower resistance with some threshold in a battery powered device that needs to sleep most of the time is probably more complicated. I would guess waking up on a pin state change is built into most microcontrollers, while measuring resistance to make it wake up requires additional components?
    - mattmaroon 3y ago
      Ah! I guess I just assumed water closed a circuit between two probes or something. I’ve never actually used one. The door sensors on my alarm do make it many different noises on open/close so that one must trigger on both. How cool.

shellfishgene 3y ago

Door/window sensors also work and are even smaller than the leak ones. Just replace the reed switch with whatever.

timemct 3y ago
Some d/w sensors will even have dry contacts specifically meant for wiring in whatever open/close type thing you'd like to use, like a pressure pad.
mattmaroon 3y ago
I didn’t realize there were any that weren’t part of an alarm system/proprietary but it seems the same company makes those too. I guess that would also be a really easy to do the opposite (if it mattered) since a reed switch triggers the action when it opens, but a leak detector when it closes. Or I guess maybe they do both. I am curious why the leak detector is bigger if it’s a simpler device. Basically the same thing but without the reed switch right? Maybe just to make room for more battery since you actually care how big the door sensor is.
- shellfishgene 3y ago
  Door/window sensors usually send a signal on state change from closed to open or the other way around. I think a leak sensor is more complicated because it needs to detect a somewhat lowered resistance between the contacts, as opposed to the door sensors that will get a fully closed/opened reed switch on activation. Detecting lower resistance with some threshold in a battery powered device that needs to sleep most of the time is probably more complicated. I would guess waking up on a pin state change is built into most microcontrollers, while measuring resistance to make it wake up requires additional components?
  - mattmaroon 3y ago
    Ah! I guess I just assumed water closed a circuit between two probes or something. I’ve never actually used one. The door sensors on my alarm do make it many different noises on open/close so that one must trigger on both. How cool.