loading
9Comments

Tell us about yourself!

Complete Your Profile
  • Home Guarduino - IoT Connected Security System

    Fair enough point however what happens if the sensor fails? you will still have your quiescent current and as such that sensor may as well not be there.You are relying on a relay to close if there is a fault, much safer to wire them normally closed in series as your second circuit shows, then if your sensor fails the sensor relay contact will open circuit.....As I said your system should be designed as "fail safe".

    Hi Allan,As I said to start with, this a good and commendable system however the N/O inclusion is a potential flaw.I spent 6 years as a signals & communications technician with our local railway system some time ago and EVERY possible point of failure was covered by a N/C contact, and as you could appreciate the failure of fault detection could result in the deaths / sever injuries of a 1000+ commuters at a time.This was to the level that too much dust on or deteriation of a particular contact point would bring that part of the track sections / trains to a screaming halt, as designed (along with a lengthy report as to the cause of the fault).Some may think I am a n a l in this regards but it is a philosophy that I have maintained for decades since then.During track maintenace 1 late...see more »Hi Allan,As I said to start with, this a good and commendable system however the N/O inclusion is a potential flaw.I spent 6 years as a signals & communications technician with our local railway system some time ago and EVERY possible point of failure was covered by a N/C contact, and as you could appreciate the failure of fault detection could result in the deaths / sever injuries of a 1000+ commuters at a time.This was to the level that too much dust on or deteriation of a particular contact point would bring that part of the track sections / trains to a screaming halt, as designed (along with a lengthy report as to the cause of the fault).Some may think I am a n a l in this regards but it is a philosophy that I have maintained for decades since then.During track maintenace 1 late evening, some "bright spark" (pun intended) physically lifted a track relay (forcing the closure of contacts) of a section of track which allowed the train driver to proceed through the unsafe section, fortunately it was in a low speed zone and at that point in time, the possibility of a collision with a freight train coming from the opposite direction existed, this did not happen however as it turned out the train was still lucky to survive as there was a train in front of it that was stopped at a station which the driver became aware of and stopped in time.Is this an extreme example, Yes. It may however somewhat emphasize my point regarding a failsafe system.I stand by these principles to this day and my primary concern was to make others aware of possibly previously unconsidered issues.Kind regards

    I am not sure we are looking at this the same way, if in a normally open circuit as described in the ible and the sensor was broken away, you would still have no alarm as the circuit would still be open circuit, If it is a normally closed circuit and the sensor is ripped away, you then have an open circuit and the alarm is them raised.From a logic perspective a closed circuit gives you a logic 1 and all is good, break the circuit and you get a logic level of zero which equates to an alarm.

    The irony of a smoke alarm catching fire is not lost on me. Yes it did set itself off.

    View Instructable »
  • Home Guarduino - IoT Connected Security System

    This looks gr8 except for 1 small issue that I noticed, that being the zone sensors should use normally closed contacts where possible.This provides a fail safe feature i.e. if your signal cable breaks, the monitor fails or some one goes snip snip on the cables (none of which will create in any event if you are using normally open contacts).Just a passing thought

    View Instructable »
  • Daggs42 completed the lesson Class Overview in the class 3D Printing Class2 months ago
  • Daggs42 commented on mainbreak's instructable Toilet Roll Dispenser7 months ago
    Toilet Roll Dispenser

    I am going camping in a few weeks and this is my plan.pull the paper out a bit, lightly twist on the lid, cover the top with a party balloon.Problem solved ? don't know, I will let you know if I come back with a wet bum.

    View Instructable »
  • Daggs42 commented on J-Max's instructable Perfect (3d Printed) Hinge7 months ago
    Perfect (3d Printed) Hinge

    Hi Sebastian there is a link to thingiverse in the description

    View Instructable »