Project: Switching a 60W, 12V DC siren ON / OFF with an arduino

Using Arduino Project Guidance
1

Hi all,

I am working on my first Arduino project and would need some help from you guys as I am a SW engineer with very basic knowledge of electronics.

Short description of the project:
I would like to switch ON / OFF a siren using a 12V trigger signal which is generated by another device. However, I want to ignore the trigger signals which are shorter than cca. 3 seconds.
A simple diagram representing the idea:

Idea (1).png

That being said, I can think of 2 ideas on how to solve this challenge:

  1. With an electrical circuit (I have zero idea on how to do that)
  2. With an Arduino and a relay

I figured I'd go with the second option simply because I believe I can implement it with some support from you guys :slight_smile: But I am open to hear reasons why option 1 would be much better.

Anyway, going for the second option, here is a diagram of how I would connect everything together:

Connections.png
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Here are the components from the diagram, which I was planning on using:
Component A
Component B
Component C
Component D

Here are some of the doubts / questions I have about the diagram I drew:
-Are the chosen components OK for what I am doing?
-Can Arduino and relay be powered by the same power adapter?
-Should there be a ground connection between Arduino and Triggering device?
-Can I get rid of the relay completely and use Arduino as a relay?
-Are all the electrical connections OK?
-Are the AC / DC currents handled correctly?
-Will this work at all?
-Is there anything that could be done better?

Thank you very much for your inputs! Looking forward to your feedback.

2

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

If you read this, you will find how to attach and display your images in your post.

You can do what you need in software, it just the interfacing that needs sorting out.

Tom.. :slight_smile:

3

Hi,
Your connections are in the right ball park, but a couple of things.

  • The triggering device will have to have its gnd connected to the Arduino gnd.
  • The 12V trigger signal will have to be scaled down to 5V for the Arduino, use a potential divider.

Connections.png
Connections.png851×421 7.3 KB

Others may have more to add.

Tom.. :slight_smile:

4

Hi,
What is the purpose of the siren, the one you have chosen is a megaphone.
There are purpose built sirens if you google.

Tom.. :slight_smile:

5

Tom, thanks for the welcome. I managed to integrate the images into the original post :wink:

I thought the ground has to be connected, but I wasn't sure since the triggering device and Arduino are hooked up to different power supplies. Will it work like this?:

Connections3.png
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The 12V output from the triggering device was actually meant for powering a smaller 110db siren, but I want to use it as a trigger for a louder siren. The reason for using that megaphone is because it's the loudest siren I could find. It outputs sound of 330db while all others output way less.

For scaling down 12V to 5V I added Component E, since I am not really skilled in making electric circuits :slight_smile: Will this component work?