Hi All,
I am looking for a circuit that would allow a laser to close a switch. Laser would be just inches from said switch. When beam from Laser is not present the switch opens and sends a wireless signal.
Can someone help with this design?
David
Are you familiar with a photocell? They can be had many places, including Radio Shack. Basically they vary their resistance from a couple of ohms when exposed to light to a couple of megohms when in the dark. Add a variable resistor (pot) in series and they can be used to sense light, the output is a voltage swing. From there you can use a digital IC, 555, or a transistor to switch.
David Cook at RobotRoom.com already wrote up a great system, he used 2 LDRs and a comparator, so when you shine the laser at one LDR it is detected.
This is pure genius because it removes any issues of ambient light level AND it also gives you 2 sensors so it can be used for on/off or up/down remote control etc.
I guess I wasn't specific enough, I wasn't talking about power, I was wondering what it's wavelength is, IE what colour is it? I don't think CDS photocells will pick up an IR laser, but I'm not sure. They're very close in spectral responce to the human eye, though I think there is a bit more towards the high end.