Button Pusher for Time-Lapse Photography
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This article is being cross-posted in:

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.