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