Cheapest way to have a bright flash?

Hello all!

I’m currently trying to make a basic domotica system.
I need one central box which “warns” me when something happens. As I’m deaf, I can’t use sound signals to indicate this, thus I need a visual signal.

The box will not always be in line of sight, but even when I’m not directly looking at it, it should be clear when an event happens.

I am trying to find the cheapest way to solve this poblem. The flash should be very bright, as it should always be clearly visible, even when the sunshine floods my living room. I wouldn’t mind using colored leds, as those might maybe more noticeable, however I have no idea whether or not colored leds would be cheaper / as bright(/noticeable) as white leds.
It should be able to run off 5v or 12v.

I would like the total price of the LEDs + resistors to be under 4$. I am not going to use a constant current driver as those make things more expensive, and the leds are going to be flashed very briefly and will be used indoors, so the temperature shouldn’t be too much of an issue.

Sorry for not being very specific, but I am open to all suggestions and ideas, maybe even something I haven’t thought of yet.
Can anyone help? <3

I need one central box which "warns" me when something happens. As I'm deaf, I can't use sound signals to indicate this, thus I need a visual signal.

Warning - watch out these seem very very bright, do not look directly in them !

alternative might be a small device that you wear and that vibrates?

Thank you for the reply.

I checked out the LEDs, but I'm not sure if I would use such a led, it'd be visible if it would flash several meters behind me in full daylight? Would just one be enough or would I have to use multiples?

I rather not use something wearable, as my husband is deaf too and I would like to allow him to see the events too. :) Besides, I'm not too fond of batteries and such, the solution would be powered from a 240vAC to 12vDC wall wart which would also power the Arduino I'll be using to receive events and flash the light. :)

pearldragoness: I checked out the LEDs, but I'm not sure if I would use such a led, it'd be visible if it would flash several meters behind me in full daylight? Would just one be enough or would I have to use multiples?

The visibility depends also on the location of the led, the direction it is pointed to, the layout of the room, the furniture, the colour of the walls/ceiling/furniture etc. In full daylight any light is harder to see than in the evening so you might need a handful placed on "strategic locations".

I would start with one just to see its visibility, and look for a good pattern - e.g. 20 seconds ON/OFF (strobo) bursts is more visible than one 20 seconds ON

Does it have to be one flash, or could you have several flashing together at different locations?
http://www.dipmicro.com/store/index.php?act=viewCat&catId=515
The 20,000mCD White LEDs here are Waay bright! I ended running them at just 2-3mA from 5V source to really tone them down.

http://www.allelectronics.com/make-a-store/item/STROBE-3B/BLUE-XENON-FLASHER/1.html

pearldragoness:
I am trying to find the cheapest way to solve this poblem. The flash should be very bright, as it should always be clearly visible, even when the sunshine floods my living room.

Why don’t you try picking up an old flash gun for about $5. You only get one flash at a time but you won’t be left in any doubt when it goes off. You might even see it with your eyes shut. They often have about 150v on the trigger so don’t connect it directly to Arduino.

LEDs are for wimps…

Hello!

Thank you for all the replies, again! I am probably going to buy several LEDs from the site Crossroads mentioned, and file them so they will be more diffuse. Going to buy blue & red & white, so I can have it act like a police siren with some flashes in between. :P

To the others, I would also much rather use Xenon flash tubes myself, but I can't seem to find something cheap enough (>4$) to use in this project. I need it to be cheap, as I might want to produce this in higher quantities later, having a lot of deaf friends which are interested in this project too. If you manage to find something cheap, I would much rather use this instead of the white leds.

But I'm definitely going with the blue and red leds, because hey, who wouldn't like police lights in their living room? :D

Xenon flash? Find your local film processor (that could be difficult now) and get a few disposable flash camera hulks for free. Note that they operate from a single 1.5V battery - it might be easiest to just use the battery "as is". You would just need a two relay module (about $2.50 on eBay) to sequence power and flash from an Arduino.

LEDs? Some white LED strips from eBay, operate from 12V, less than $4 (you meant to say) if you look carefully (and can wait) working off 12V. Switch with a transistor.

The ultimate method would be to design a small circuit to fire off a xenon flash (old disposable cameras), using a transformer to step up and charge a capacitor (200vdc+), and then fire it off as a bright very bright flash of light.

Failing that, a 10watt white LED along with a 12v battery would be more than capable of getting your attention even on a sunny day (which the 5mm/10mm LED's wont really do)

Maplins used to do some cheap xenon flash kits.