I've tried to use a Velleman timer kit for time-lapse photography with my Pentax DSLR camera but the single relay output isn't enough.
The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact on the plug is shorted to the one nearest the body (triggering autofocus etc) and when the button is pressed further in, these two contacts remain shorted but the contact furthest from the plug's body is then also shorted to trigger the shutter release.What's needed for the 555 time-lapse circuit is second relay whose Normally Open contacts close as well, a fraction of a second after the first one. All 3 connections were shorted at this point when I checked the manual cable release with a continuity tester.
I've considered adding a single transistor triggered by the 555's output but with a simple RC time delay, e.g. its base taking a finite time to reach a sufficiently high voltage to turn the transistor on, and consequently activating the relay.
I'd be grateful for any suggestions to achieve this result. It's been years since I've done much with a soldering iron and electronic construction. Maybe I should be using a thyristor instead of a transistor, or a Darlington or something. I want to keep it simple.
Thanks in advance, Dave. 3000 photos especially Edinburgh & Scotland. + 3D rendered art, old ads etc. Délété david for email; watch the spam filters.