Author Topic: Door open timer switch thingymajig  (Read 1258 times)

  • Offline zpyder

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Door open timer switch thingymajig
on: July 08, 2021, 00:15:26 AM
Hi all, here's an interesting electronics project/problem.

At work we have a desiccating cabinet that is used for drying filter papers and things out. Our technicians have a bad habit of leaving the door open, or unlatched, resulting in normal air getting into the cabinet and so the stuff that's meant to be dry ends up with some residual moisture.

I built a simple buzzer alarm that would sound whenever the door was open. Was just a buzzer, 9V battery, and a magnet reed switch on the door. The issue was that the proximity required for the reed to switch states meant that the buzzer wouldn't sound if the door was pushed closed and not latched - which isn't acceptable.

I'm now wanting to build a buzzer V2.0, with improved functions:
  • Time delay so that the door can be opened, something put in/taken out, and closed, without the buzzer going
  • Sensitive enough that the door absolutely has to be closed for the buzzer to not go off. The slightest crack is not good


If anyone has any recommendations that'd be good. Cheapest, simplest option is preferred, I'd love to do a raspberry pi thing but I think that's overcomplicating it. I'd also love to be able to say to the technicians to make sure the door is closed and for them to actually do it, but that's never going to happen either...

Re: Door open timer switch thingymajig
Reply #1 on: July 09, 2021, 18:30:32 PM
Use an ESP8266, such as the Wemos D1 Mini, you can power from USB, costs about £2-3 and will run Arduino code programmed direct from the Ardunio IDE, can attach a piezo speaker, if you want to internet connect then has wifi, has multiple IO so you can connect reed switches/ ultrasonics / hall sensors.. whatever you like and will simply do timed delay without the overkill of a Pi..

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #2 on: July 10, 2021, 21:28:24 PM
I decided to get an arduino starter kit so I can just have fun learning the whole ropes. Was the equivalent of £30 from the nz equivalent of maplin. Having fun so far :D

Re: Door open timer switch thingymajig
Reply #3 on: July 10, 2021, 21:55:18 PM
Cool basically if you get something working, I’d recommend still running it from an ESP just because they are smaller, cheaper and usually more powerful.. if you need any help let me know

  • Offline Serious

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Re: Door open timer switch thingymajig
Reply #4 on: July 19, 2021, 14:50:36 PM
 Obvious answer would be an automatic closer, same as on fire doors, problem is some idiots tend to put things in the way to stop the door closing.

FRIDGGI actually produce a fridge open alarm, exactly what you are trying to make, for about £20, bound to be other options.

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #5 on: August 03, 2021, 21:16:30 PM
Got a prototype working with an Uno, now sorting out a polished version on a Leonardo Tiny.

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Re: Door open timer switch thingymajig
Reply #6 on: August 03, 2021, 21:36:51 PM
Nice work! The Wemos D1 Mini BTW has stackable proto boards

Here’s an IR setup I built

https://imgur.com/a/4KLUX6H
Last Edit: August 03, 2021, 21:41:33 PM by XEntity #187;

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #7 on: August 10, 2021, 20:12:13 PM
Installed and working.

Colleagues have already begun feature creeping requests for the next version haha.

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  • Offline Clock'd 0Ne

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Re: Door open timer switch thingymajig
Reply #8 on: August 11, 2021, 09:01:08 AM
Impressive how quickly you put it together, nice job!

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #9 on: August 31, 2021, 04:53:56 AM
Wasn't as hard as I thought it would be. I've learned a fair bit of VBA for excel I think my job in the last 2 years. Gave me a good enough coding foundation that once I got used to the syntax it was fairly transferable.

And then the electronics... So long as I think of the pins as integers or boolean variables that's not too difficult either.

The hardest bit is soldering and just knowing little tips and tricks like always needing a resistor on an LED etc. I've blown one clone mini Arduino up with a short circuit somewhere (I think) but they're pretty cheap so not too concerned.

Once I finish a Udemy course on it I've got several projects in kind. I want to make an air quality monitor (rotorua is very bad in terms of geothermal sulphur, smoke from wood burning stoves, and pollen) and a small robot to send under our house to try and figure out where the ants are coming in. I can crawl under there but it's super creepy and a squeeze!

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Re: Door open timer switch thingymajig
Reply #10 on: September 06, 2021, 12:47:35 PM
how do you dry the cabinet out?   or is that a tray of desiccant in the bottom?

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #11 on: September 06, 2021, 20:28:57 PM
Tray of silica dessicant in the bottom. We have two of them. Each morning we swap the one in the cabinet out with the other one which has been drying out in an oven set to 104 degrees celcius.

Daily swapping is overkill as the dessicant goes pink when it's used up, and never does. We used to go about a week between changes but found without strict protocols the technicians slacked... Hence this alarm!

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Re: Door open timer switch thingymajig
Reply #12 on: September 08, 2021, 21:50:42 PM
Tray of silica dessicant in the bottom. We have two of them. Each morning we swap the one in the cabinet out with the other one which has been drying out in an oven set to 104 degrees celcius.
Daily swapping is overkill as the dessicant goes pink when it's used up, and never does. We used to go about a week between changes but found without strict protocols the technicians slacked... Hence this alarm!
Sent from my SM-G998B using Tapatalk

well in that case.... phhhh have I got something sexy for you!

https://www.youtube.com/watch?v=Vabq-s62IVM

:-)

  • Offline zpyder

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Re: Door open timer switch thingymajig
Reply #13 on: September 08, 2021, 22:46:19 PM
Tray of silica dessicant in the bottom. We have two of them. Each morning we swap the one in the cabinet out with the other one which has been drying out in an oven set to 104 degrees celcius.
Daily swapping is overkill as the dessicant goes pink when it's used up, and never does. We used to go about a week between changes but found without strict protocols the technicians slacked... Hence this alarm!
Sent from my SM-G998B using Tapatalk

well in that case.... phhhh have I got something sexy for you!

https://www.youtube.com/watch?v=Vabq-s62IVM

:-)
Oohh... Intriguing.

I'm currently making a temp/humidity/uv meter.

The silica is probably a bit quicker. Though it's making me think that perhaps I could make a fan that circulates air inside when the door is closed and the humidity is above a set level.

Sent from my SM-G998B using Tapatalk
Last Edit: September 08, 2021, 22:48:06 PM by zpyder #187;

Re: Door open timer switch thingymajig
Reply #14 on: September 14, 2021, 21:49:03 PM
a fan should make a a massive difference...

you'll defiantly have a dryer area around the silica and a wetter area around the stuff being dried

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