I'm working on a project and have very little circuit design experience or background. I've been through the thread "Fast Horses" and several others that looked helpful, but haven't had time to go through the entire forum so any pointing to relevant threads is appreciated. Here's what the circuit needs to do: 1. Detect a laser beam 2. Turn on two LEDs that remain on as long as the laser is detected (one is part of the circuit and one LED is external to the circuit) 3. Send a pulse signal to a DAQ card that the laser has been detected 4. Send a pulse signal to a DAQ card that the laser is no longer detected I'm working with a set 12 DC source, a Hamamatsu S2386-5k to detect light, and I'm trying to get ahold of a green laser pointer for testing. Of the ICs that I have available, I settled on a LM 741, LM 339, and LM 555 as a starting place for a test circuit on a bread board. I can't use the breadboard set up with the actual laser that it will be used for so I'm trying to do as much pre-thinking and incremental testing as I can. I've been working mostly from datasheets and any sample circuits I could find online or in textbooks. I've attached a picture of a "rough draft", bare bones circuit that I've put together. I don't have any circuit design software so I just drew it up in paint, but I think it's readable. Any suggestions, ideas, criticism, etc., is appreciated. Thank you.