There are many forms of remote control methods, including infra-red, RF wireless data, thowing a tennis ball at a switch and so on - but the following project is the first time we've seen it done with lasers. Yes - Instructables member XicoMBD has described a method that uses an Arduino compatible circuit to measure the values from a light sensor - and when there's a large chnage in the value (from having a laser pointed at the sensor), the state of a relay is changed and thus a remote control with a difference is born.
It's a novel and potentially dangerous method but different all the same. To minimise the mains-related wiring the creator has hacked into an outlet with circuitry to control the mains-rated relay (from a wireless RF outlet) however an Arduino can also control a relay directly with the appropriate circuitry. For a fun demonstration of the system check out the following video:
If you're looking for a simple way to control many relays from your Arduino, without using up all your digital I/O pins - check out our Relay8: driver shield:
So what is the RELAY8:? It's an Arduino shield that allows you to drive up to 8 relays from your Arduino using just 2 I/O pins with this shield. It communicates with your board using I2C, so you can even stack several shields together to drive 16, 24, or more outputs! Includes back-EMF protection and works with a wide range of relays. Perfect for home automation projects! For more information and to order, click here.