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MATERIALS
Passive infrared motion
detector DSC’s Digital
Bravo BV-300DP has
room enough to fit the
other components inside
its case. Available from
the Home Security Store,
homesecuritystore.com.
USB interface with cable USBmicro part #U421,
usbmicro.com
DC/DC converter, 5V to 12V I used the
Cincon EC1SA02N, Mouser Electronics
part #418-EC1SA02N,
mouser.com.
1kΩ resistor Mouser #291-1K-RC
22-gauge signal wire aka hookup wire, various colors
Double-sided mounting tape
Windows PC running free USB Media Presenter
software Download it at
kadtronix.com/
downloads/usbmediapres10setup.zip.
Audio and video files for presentation
TOOLS
USB Motion Detector
C NC Gnd 12V
Gnd
12VDC
1000Ω +5VDC
Converter
EC1SA02N
12
4
6
USB Micro U421
24
23
22
21 2019 18 17 16 15 14 13
123456789101112
Wiring diagram.
resistor. Note that the 4 pins of the SIP package
version of the DC converter are numbered 1, 2, 4,
and 6, to match the pin numbering on other versions
of the component. Leads run from terminals 9 and
14 of the USB interface PCB to pins 2 and 1 of the
converter, respectively. Pin 1 of the converter connects to the resistor, and pins 2 and 4 connect
together. Solder leads to converter pins 2 and 6, and
connect another lead from USB PCB terminal 2 to
the hole on the seam where the 2 halves of the the unconnected end of the resistor, but leave them
enclosure meet. Do not let the drill bit penetrate loose for now (Figure B); we’ll attach them when
more than ½" inside the unit, as this can damage reinstalling the detector PCB.
internal components (Figure A). Arrange the pre-wired components inside the
To open up the detector, first unscrew the retaining detector case, and secure them to the back shell
screw, if the unit has one. Then firmly grasp the unit with double-stick mounting tape. Be careful not to
in your left hand and use your right hand to pull obstruct the area where the detector PCB will be
the halves apart while gently pushing down on the reinserted. The components should fit just under
retaining tab with a small flat-blade screwdriver. the detector PCB without making contact (Figure C).
Set both halves aside. Now, reinstall the detector PCB and secure it
At this point you’ll start handling static-sensitive with the small original screw. Complete the wiring
electronic components, so you are strongly advised as shown in the wiring diagram: USB PCB terminal
to wear an antistatic wrist strap clipped to a suitable 2 and resistor to terminal NC, DC converter pins
electrical ground. This will protect the components 6 and 4 to 12V and Gnd, and terminal C bridged to
from damage from electrostatic discharge. Gnd (Figures D and E). The PCB has screw terminal
Use a Phillips screwdriver to remove the screw blocks, so you don’t need to solder. The NC (
nor-that holds the detector’s printed circuit board. mally closed) and C (common) terminals serve as
Carefully remove the PCB and set it aside. a switch that turns things on and off, and the USB
Solder short ( 2") lengths of signal wire follow- interface routes this signal to the computer.
ing the project wiring diagram (above) to pre-wire Close the detector case back up; that’s it for
the USB interface, DC voltage converter, and 1kΩ the hardware!
Photograph by Ken Delahoussaye
Soldering iron and solder
Antistatic wrist strap aka ESD wrist strap
or ground bracelet
Wire strippers
Small cable tie
Screwdrivers: Small flat-blade and Phillips
Drill and
6" drill bit
Multimeter
166 Make: Volume
16
