Simple Photodiode On/Off circuit

[bodgetts]

Thanks for the help. I will try your idea with the comparators, as it sounds like the easiest to implement. Can you recommend the best chip for this particular job?

I am making a shooting target game, so when they pull the trigger I will turn on the laser and see if it has hit any of the targets. I will pulse the laser at a slightly different rate each time to stop people cheating.

[Jumper]

LM393 or similar low cost comparator would work. You can also try using a normal OP-amp as a comparator. National have tons of comparators and OPs that will do the job.

What do you mean by "I will pulse the laser at a slightly different rate each time to stop people cheating". Will you have more than one gun fireing at the 8 targets at the same time or??

[Jumper]

Read this: http://www.national.com/an/AN/AN-31.pdf (useful ways to connect an OP-amp)

They have 3 suggested circuits for photodiodes and I suggest you look at them and figure out if you can use them. There is a reason why these circuits are made :-)

[bodgetts]

If I just accepted that when the laser hits the diode that the target has been hit, there is nothing stopping people just using a standard laser pointer and triggering the targets. If they use the proper 'gun', it will pulse say 5-10 times in quick succession, or some other pattern that I can recognize, I don't think people will be able to flash their laser pointer that fast. I also will probably use a slightly different pattern each time.

[cncmachineguy]

If you use different patterns for each gun, you can easily keep score for each player