111 lines
5.6 KiB
Plaintext
111 lines
5.6 KiB
Plaintext
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\ \ \ \ \ \ \ \ \ \ \ \ \ \ \
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\[____________________________[_ \ /
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\[ The Chrome Box [_ A Portable Self-Contained Device
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\[ 14-JUN-88 [_ / to Manipulate Traffic Signals \
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\[ Outlaw Telecommandos [_ / by Remote Control \
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\[ Modem Free Earth [_ / \
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\[\\\\\\\\\\\\\\\\\\\\\\\\\\\\[_ -=p*p=-
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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Emergency vehicles in many cities are now using devices called OptoComs.
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OptoComs are a system of sensors on traffic lights that detect a pattern
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of flashes from vehicle-mounted strobe lights.
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This flash pattern varies from city to city depending on the manufacturer
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of the equipment used. Often the sensors are installed only at major
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intersections. Nevertheless, the Chrome Box, which simulates these strobe
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patterns can often be used to give your car the same priority as an
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ambulance, paramedic van, firetruck or police car.
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Because of the varying patterns on different systems this phile will
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outline a general procedure for making the Chrome Box.
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Decoding Flash Patterns:
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First, you need to observe an emergency vehicle in action. You can wait
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until you encounter one by chance, running out to see when you hear a siren,
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or when you pull over in your car to let one pass by. You might wait
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near a fire station for the next emergency to occur. Or, if you are very
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impatient, you can summon one by calling in a false alarm (not recommended in
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areas with limited services - that could divert attention from a real
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emergency). If the OptoComs in your area are the kind with a pattern of single
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flashes at a steady rhythm, you have merely to buy a strobe light at Radio Shack
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& adjust the flash rate until you can induce a traffic light to change.
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If the flash pattern is more complex, you can videotape the emergency vehicle &
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then play back the tape in single-frame mode, counting the number of frames
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between each flash. Each video frame is 1/30 of a second, using this you can
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calculate the time between flashes in the pattern. Another way is to count the
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number of flashes (or flash-groups) in one minute and use that to compute the
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rate. Counting video frames will give you a good idea of the spacing of the
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flashes in a complex pattern. For really accurate information, call the fire
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station & ask them, or write to the manufacturer for a service manual, which
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will include a schematic diagram that you can use to build one. A good cover
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story for this is that you are a consultant & one of your clients asked you to
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evaluate Optocom systems, or you could pose as a free-lance journalist writing
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an article.
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Modifying the Strobe Light:
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You may not have to modify the strobe at all. But if you need a faster
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flash rate than your strobe allows, open it up & find the large capacitor
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inside. Capacitors are marked in microfarads, abbreviated as mf,mfd or ufd.
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By replacing the capacitor with one of the same voltage-rating (usually
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250 volts or more) and a SMALLER value in microfarads, you can increase the
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flash rate. Halving the microfarads doubles the rate.
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The other component that can be changed is the potentiometer (the speed
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control device with the knob on it). Using a smaller value (measured in
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ohms or Kilohms, abbrevaited with the greek letter 'omega' or the letter K)
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will speed up the strobe. There may also be a resistor (small cylinder with
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several colored stripes on it, and wires coming out of each end). Replacing
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this resistor with one of smaller value will also speed up the strobe.
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To generate a complex pattern, you will either have to design and build a
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triggering circuit using IC chips, or rig up a mechanical device with a
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multiple-contact rotary switch and a motor. It HAS been done.
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To modify the strobe for mobile operation the simplest thing is to get a
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110-volt inverter that will run off of a car battery by plugging into the
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cigarette lighter & run the strobe from that. Or, you can figure out (or find
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in a hobby electronics magazine) a strobe circuit that will run from batteries.
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Battery-powered strobes may also be availble, either assembled or as kits.
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Stealth Technology:
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Most light sensors and photocells are more sensitive in the infrared area of
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the light spectrum. Infrared (IR) is invisible to the human eye. Putting an
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infrared filter over the strobe light may allow the Chrome Box to operate in
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traffic undetected by police or other observers. IR filters can be obtained from
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military surplus sniperscope illuminators, or from optical supply houses like
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Dow-Corning or Edmunds Scientific Co.
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Using the Chrome Box:
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Mounted on your car, the Chrome Box can guarantee you green lights at major
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intersections in cities that have OptoComs. Handheld Chrome Boxes may be used to
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create gridlock by interfering with the normal flow of traffic. If you have
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access to a window overlooking a traffic light, you can play pranks by switching
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the signals at inappropriate moments, or you can plug the strobe into an exposed
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outlet at a laundromat or gas station.
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Some Decoded Patterns:
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Torrance, California
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Standard large Radio Shack strobe lights are used. Moderately fast rate.
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* * * * * * * *
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Manhattan Beach,CA
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Flash-pairs in a 4:1 ratio, at a rate of 2 flash-pairs per second.
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* * * * * * * *
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<------ 1 sec ----->
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******************************************************************
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* Please add any new patterns or info you discover to this Phile *
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******************************************************************
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Thanks to those who posted observations on the South Bay WWIV's.
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---------------------------------------
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