Mosque Time-Lapse Surveillance Camera


Overview

This is a simple add-on hack to turn a Vivitar Vivicam 3350B digital camera (available at Wal-Mart for $20) into a time-lapse surveillance camera.  This is useful for staking out Mosques, $2600 meetings, the Canadian embassy, Euro-savage embassies, and other people who have yet to prove they should be allowed to live.

The operation is quite simple.  A 555-timer is used to "pulse" the camera's shutter button once every 20 seconds or so.  The reason this is done in 20 second intervals is that the camera has an internal "shutdown" timer that is set for 30 seconds, and I don't think it is possible to disable this timer.  The camera is capable of two resolution modes: 640 x 480 pixel mode (VGA) and 320 x 240 pixel mode (QVGA).  The camera is capable of holding approximately 54 pictures in VGA mode and 250 in QVGA mode.  The capacity is limited by the camera's internal 8 MB SRAM chip.  Increasing the memory size is technically possible, but probably not worthwhile.  For surveillance applications, the Low Quality mode (QVGA) will be chosen for an approximate time-lapse of 80 minutes.  Real-world times will differ, as the 555-timer's pulse times vary with temperature and component tolerance.  To be on the safe side, return to the camera and download the pictures once every 60 minutes.  Note!  Download the pictures from the camera before removing the camera's battery power, otherwise the pictures may be lost.  There is an internal battery backup, but I wouldn't trust it.

Math

The 555-timer circuitry is quite simple.  Refer to the resistors R1 and R2, and capacitor C1 in the schematic.  The math to determine the 555's approximate pulse widths (time) is as follows:

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Output of Pin 3 of the 555 Timer

HIGH Time = 0.69 * (R1 + R2) * C1
LOW Time  = 0.69 * (R2 * C1)

Example:

R1 = 470k (470,000 Ohms)
R2 = 47k (47,000 Ohms)
C1 = 47 µF (0.000047 Farads)

HIGH Time = 0.69 * (R1 + R2) * C1 = 0.69 * (470,000 + 47,000) * 0.000047 = 16.76 seconds
LOW Time  = 0.69 * (R2 * C1) = 0.69 * (47,000 * 0.000047) = 1.52 seconds
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A single 2N3904 transistor level shifter is used to convert the 555's low pulse into a high pulse, which in turn, activates the camera's shutter button via another 2N3904 transistor.  (The camera waits 17 seconds then "pulses" the shutter button for 1.5 seconds, simulating pressing the button).  Feel free to experiment with the 555-timer's timing component values.  The use of precision tolerance (1%) resistors and capacitors will allow you to extend the shutter control pulses closer to the maximum of 30 seconds.  You could even reduce the pulse times for a quicker time-lapse.

The timer should be powered off an external, isolated 6V battery pack.  It is best to make the 6V battery pack out of four "C" or "D" cell batteries.  Plastic four-cell battery holders are available from Radio Shack (Part Numbers 270-390 [4 "C"] & 270-389 [4 "D"]).  Use the 6V output to power the timer and any external infrared LED lighting.  You should also make an (optional) similar battery pack using two "C" or "D" cell batteries to power the camera.  This new 3V battery pack will be used in place of the camera's two internal "AAA" batteries.  The camera's DC power is fed by the internal red (positive '+') and black (ground '-') wires, which are clearly seen and labeled inside the camera.  This new battery will allow the camera to operate for a significantly longer time, especially if you use "D" cell batteries.  For reduced space applications (i.e. covert), you can even use a series of flat, 3V lithium battery cells.  The timer's ground and the camera ground can not be connected.  I'm not sure why this is needed, but that was the only way I could get the circuit to work.  To avoid this, use separate battery grounds or use a relay to connect pins 1 & 2 on the shutter button instead of a transistor.

Internal view of the Vivitar Vivicam 3350B digital camera.  There are screws along the bottom and sides that need to be taken out in order to open the camera.  The large black "blob" is the camera's microcontroller potted in epoxy.  The round disk with the two yellow wires is the beeper.  Remove this (cut both wires) to disable the beeper and make the camera operation more "covert" (no damn beeping).  The black thing with the plastic lens is the camera lens, duh.  The actual CMOS imager is underneath this lens.  To get at it, remove the two screws on the board's backside.

Close up picture of the camera's front PC board.  The shutter button is on the upper left.  The switch's pins are labeled 1, 2, 3, and 4.  You'll only need to connect wires to pins 1 & 2 to activate the shutter.  The camera's DC power input (from the "AAA" battery pack in this picture) is on the bottom.

Close up picture of the camera's back PC board.  The select/power button is on the upper left (PCB mount).  The two screws on the left hold the plastic lens assembly to the PC board.  The exposed pads shown in the middle of the picture are for the camera's LCD screen.  Be very careful removing this, as they tend to never work right after removing them.  The LCD screen is not needed for the camera's operation, and can be discarded.  The large black IC is the camera's main memory.  Note the small 3V lithium cell for memory backup.  The input connector on the left is for the computer transfer cable.

555-based shutter button control using all surface mount components.  This allows the timer to mounted inside the camera.  DC power is from the top (near the 555's pin-8).  The output from the bottom 2N3904 goes to shutter button pin-2.  Ground goes to the separate 6V power supply and shutter button pin-1.

Close up picture of the camera's front PC board with the plastic lens assembly removed.  Be sure to not get any dust on the CMOS imager's window.

Internal picture with everything hooked up.  The beeper, eyepiece, and internal battery pack have been removed.  The wires going out the bottom are for the separate DC power supplies.  The yellow wires connect the shutter button to the control timer.

Example photo from the Vivitar Vivicam 3350B digital camera in High Quality (VGA) resolution mode.

Example photo from the Vivitar Vivicam 3350B digital camera in Low Quality (QVGA) resolution mode.