Query on which Arudino board for safety gate alarm

Hi everyone.

Here's my first post ever here. Nice to virtually meet you all :slight_smile:

A little relevant background on myself. I have a Degree in Electronics & Computer Engineering from about 16 years ago. I've worked as a Software Developer almost all the time since then. Hardware knowledge is basic as a result :smiley: But I do have a reasonable concept of hardware principles. I still have my soldering iron and can still solder when needed. I've done the odd hardware project including a Raiden costume for Halloween a few years ago. For that project, I used an Arduino Mega wired to some Adafruit digital LED strips (Overview | RGB LED Strips | Adafruit Learning System) to get a lightning effect. It worked out well (even if I say so myself) though the wiring was a spaghetti mess under my costume :smiley:

Anyway, I now want to create a safety system for home. From time to time, someone in the house forgets the safety gate at the top or bottom of the stairs open. This is concerning obviously. I was thinking that we could make a small project that could detect when the gate was open and sound an alarm and flash an LED.

What I'm wondering is what Arduino board would I need? And maybe some direction at the LED and speaker to use? For the Raiden project, I learned that I would need the Mega as only it had enough memory to be able to store the code library required to control the digital LED strips. This time, I'm thinking the requirements are simpler so maybe I wouldn't need as much memory? Something small would be nice so that it's not in the way. But as long as it would have the specs to be able to control and power a speaker that is loud enough and an LED.

Any and all help and guidance very much appreciated in advance :slight_smile: Thanks.

So the only requirements are to sense to state of the gate and control an LED and emit a sound through a speaker?

How will the device be powered?

No Arduino will directly drive a speaker that will make a sound loud enough to hear from much distance. An amp is necessary. That could be just a transistor. What sort of sound?

What is the LED? Describe what you want it to do. How big? How bright?

How are you going to sense the gate state? Hall Effect sensor? Reed switch? Optical device?

A Nano is small in size and may meet your requirements.

Or get an ESP8266 and connect it to your wifi as well so you can send phone alerts in addition to led/alarm.

These buzzers are quite loud and can be directly driven from an Arduino pin: Buzzer 5V - Breadboard friendly : ID 1536 : $0.95 : Adafruit Industries, Unique & fun DIY electronics and kits

I can easily hear the one in my garage when the door between the house and the garage is shut, and a similar one in our dining room can be heard throughout the house.

WOW! What a response after less than one day! Great forum. Thanks guys!

These buzzers are quite loud and can be directly driven from an Arduino pin: Buzzer 5V - Breadboard friendly : ID 1536 : $0.95 : Adafruit Industries, Unique & fun DIY electronics and kits

I can easily hear the one in my garage when the door between the house and the garage is shut, and a similar one in our dining room can be heard throughout the house.

This sounds perfect. I'll look into this. Thanks!

I watched the video at 6:25 in. "Very loud and very annoying" as the lady with the pink hair puts it. Just what I'm looking for :smiley: My plan is to give someone about 10 seconds before sounding any kind of sound. Starting out with short beeps before eventually getting to a continuous beep if left open for a minute or something.

Or get an ESP8266 and connect it to your wifi as well so you can send phone alerts in addition to led/alarm.

Cool idea. I might consider this. Would be fun to have :slight_smile:

What is the LED? Describe what you want it to do. How big? How bright?

How are you going to sense the gate state? Hall Effect sensor? Reed switch? Optical device?

A Nano is small in size and may meet your requirements.

For the LED, a regular sized one like you would find on an old style TV remote. But bright enough to get your attention. Perhaps a strobe light would be better? Though more battery hungry I'm guessing?
For the gate state sensor: I'm definitely open to suggestions. My initial thinking was to just have a small piece of metal that will complete a circuit for two wires on either side of the gate's catch but now I'm thinking this is too basic and prone no

Dual 555 timer? One for switch sensing, one for speaker drive?