Button Pusher for Time-Lapse Photography
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sci.electronics.design sci.electronics.basics sci.electronics.misc alt.binaries.schematics.electronic
The related binary files are posted only in the .binaries group.
In case anyone else might be interested for future reference, this is as-built documentation of a project previously discussed in these threads:
sci.electronics.design: Remote camcorder controller 02 Jul 2007 Switching +/-12V from 6/0V 12 Jul 2007
My camcorder will take still pics as well as video, and it has a remote control. I wanted to send the remote's "Photo" signal to the camcorder at a regular interval so I could do what amounts to time-lapse photography. Earlier I considered more elegant ways to do this, but ended up just rigging up a button pusher for the remote.
The project was made possible by an item from my junque box - a rare Magnecraft open-frame relay, #W88KDX-2, which I used as a solenoid. The floating contacts travel just the right distance, and with enough force, to depress the button on the remote.
Basically, the remote and the relay are mounted on a strip of wood which is taped to the tripod handle (the camera is mounted backward so its I/R detector can see the remote's I/R LED). The remote is on top, and the relay on the bottom, and the two are connected via a hole drilled through the wood strip. Materials used include popsicle sticks, a short piece of wire-wrap wire (it must be blue), masking tape, a right-angle mounting bracket, and a rubber band. A Dremel tool with a cutting disk was used to cut off the fixed relay contacts and to cut the slits for mounting the connecting wire.
The drive electronics are on a breadboard, powered by 4 "C" cells, all of which just hang from the tripod. The circuit uses one TLC555 timer to provide the interval between button presses, and an LM555 timer to set the duration of each button press. A dipswitch allows selection of intervals ranging from about four seconds to over one minute.
Since the relay requires at least 12V, and a fair amount of current, I used a MAX232 chip to convert the incoming 6V from the battery pack to a much higher voltage the relay can use, and a large capacitor to store that charge between presses. The two-transistor coil driver was suggested by James in the .design group, but the resistor values are all my fault. Thanks to James and all the others there who helped me figure this out.
I don't have a schematic drawing program, so I just drew it by hand and took a picture. I hope it's readable. If anyone has questions or comments, fire away.