davide@cs.qmc.ac.uk (David Edmondson) (10/19/88)
In article <144@snaring.UUCP> steve@alberta.UUCP (Steve Sutphen) writes: >find such a device. I have two projects that I would like this data for: >upgrading the flash level in a friends slide duplicator, and building some >experiments to try and freeze moving objects on film. I want to understand > steve. Not flash tubes but here is some info about my efforts at motion freezing by flash. A few years ago I set up a system which used a microphone, an amp, an AppleII and an opto-coupled triac to fire a flashgun on a sound trigger. Various microphones were tried, the ones they sell in Tandy for recording phone call are useful for some purposes, it depended on the shot which one was most suitable. The amp was actually a cassete deck in record-pause-monitor mode with the monitor line plugged into the cassette port of the Apple. A dozen or so lines of 6502 code read the port until a sound was detected then went through a delay cycle and fired the flash by sending a signal to the triac via the game-paddle socket. The delay was set by the Basic calling program and could be from 28micro sec to ~0.75 sec. I got some pretty good results, well I thought so anyway, my favourite being a lightbulb dropped onto an old piston and totally crazed yet still retaining most of its shape. You can use the technique for watersplash photos, dart in balloon shots etc. Well worth a try but make sure you keep all those nasty big voltages in the flash well separate from you computer. Cheers, Dave. Dave Edmondson davide@uk.ac.qmc.cs Dept. Comp. Sci. davide@qmc-cs.uucp Queen Mary College Mile End Road London E1 4NS 01-975 5250
jans@tekgvs.GVS.TEK.COM (Jan Steinman) (10/25/88)
<...A few years ago I set up a system which used a microphone, an amp, an AppleII and an opto-coupled triac to fire a flashgun on a sound trigger...> Gee, I knew there was some use left for an Apple II! Of course, you could replace the Apple with a schmidt trigger, a one-shot and a pot, which would probably be easier to adjust. :::::: Software Productivity Technologies -- Experiment Manager Project :::::: :::::: Jan Steinman N7JDB Box 500, MS 50-383 (w)503/627-5881 :::::: :::::: jans@tekcrl.TEK.COM Beaverton, OR 97077 (h)503/657-7703 ::::::