4 Feel free to play with the source code. The basic schematic is shown below, exported from DipTrace. Normally this is off, but it flashes when the camera’s being asked to focus then glows steadily when the shutter’s triggered.Ībstracting, our device takes a 5-bit input configuration (4 numbers × 4 units × 2 power modes) and generates a sequence of 4-bit outputs. I’m not sure whether this was necessary, or indeed desirable, for the camera, but still.įinally, as you’d expect, there’s also a status LED on the front panel. In total then, then are three outputs which all all opto-isolated. On top of this, I wanted an extra output so that, for example, I could break the power to the camera when it wasn’t needed (the 400D draws about 40mA when ‘resting’). That way any variation in the time the camera takes to focus won’t affect the time at which the photo is taken. It seems sensible to drive both of them independently, giving the camera a few seconds to focus before taking the photo. I want the intervalometer to drive a Canon 400D DSLR, which has separate focus and trigger inputs. For example a 5V supply could be used instead if that were more convenient.įinally one has to decide what to do when the time comes to take a photo. The whole thing is easy to power from a couple of AA batteries, but this isn’t critical. 3 To keep the power consumption down, it’s clocked with a 32kHz quartz crystal. The latter seem to offer better long-term stability, so that’s what I used.įor no better reason than I had some to hand, I based the device on a PIC 16F690. One might distinguish between analogue solutions like the ubiquitous 555 timer, and digital ones which are effectively a quartz-oscillator and a programmable divider. To actually generate the pulses there are a few choices. One can simply look at the positions of the switches to see how the device is configured: we don’t need a fancy LCD display. In fact, I used a couple of 4 way switches: one specifies 1,3,10 or 30, the other seconds, minutes, hours or days. a potentiometer and some sort of display. This naturally led me to a digital UI, rather than e.g. However, when I say one minute I really do mean one minute. a 1 minute interval between frames, but I don’t need the ability to specify 1 minute and 3 seconds. By this I mean that I want to be able to easily specify e.g. Perhaps the key decision was the high-accuracy, low-precision trade-off.
I decided that the following were important to me: 1 You can buy them ready made, and the Internet is awash with designs for DIY versions: just ask Google. Despite its active role, such things are called intervalometers. If one wants to make time-lapse movies, then one really needs a device which regularly tells the camera to take a picture.
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