Overview		Use 3 sensors mounted on a hat or headband to provide 360-degree coverage.
Protocol
5.XX Main Board
Micro MT Board
ISD Sounds
Bootloader
Sensors
Optics
Online Parts Store
The Real MILES
LTTO Protocol
LTTO Grenade

HEAD SENSORS

Compatible with 2.XX and 5.XX systems

New Sensor Design  - TSOP48XX with recommended power filter components and Hit LED.

PCB CAD FILE: Sensor.pcb  (download software @ www.expresspcb.com)  NEW    

More Details in the 5.XX Tech Reference

DIY PC Boards.  It should be fairly simple to re-draw this PCB design into any other PCB layout software.  If you want to use the ExpressPCB cad file, you will have to order the boards from ExpressPCB as the file format is proprietary.  Also, you will probably want to "panelize" the design by copying multiple times onto a larger board.  Just remember to leave enough room between designs for cutting apart.  I use a metal shear to cut the panelized boards apart, or you could use a hacksaw.  (Or you can just buy the boards from the order page.)

Should I use 40KHz or 56KHz?  You can use either one, so long as all your guns use the same frequency (similar to a radio channel).  The MilesTag gun can be set to either frequency in the configuration menus.  If you plan to use the "WoW' compatible mode in the new firmware (V5.30) you will need to use 56KHz sensors.

What is the IR LED for?  Well, that was originally intended for a few functions where the head sensors could transmit data - for things like simulated contamination, or secondary damage from shrapnel, etc.  Lots of possible ideas.  At this time though, I recommend leaving the IR LED off the board.  It will interfere with the ability to remotely respawn (or receive any signal) when the player is "tagged out" since the constant IR overwhelms the sensor (it is on when the Hit LED is on).

TSOPs and Sunlight

Effects of Direct Sunlight on TSOP sensors:  All TSOP-type sensors are susceptible to interference from direct, full sunlight, usually causing a reduction in the range from which they can be hit.  Very bright mid-day sun experienced during the summer season in many parts of the world can have a SEVERE effect on sensor performance.  TSOPs will perform best under overcast conditions, in shaded/wooded areas, or during evening/nighttime hours.  The black resin casing of the Vishay 48XX series TSOP filters out all visible light allowing only a narrow band of IR to enter the sensor.  This does help reduce interference from the sun and other unwanted IR sources, and it is possible that encasing the sensor inside additional IR-pass material may provide some performance improvement.  Increasing the power of the IR transmitter (the gun) will also help overcome the reduced sensitivity in full-sun, but there are practical limits to how much current you can pump through an IR LED before you destroy it.

It is possible to design a discrete sensor that is nearly impervious to sun interference, but such designs are much more complex and expensive to construct.  The choice to use TSOPs is a good balance between all-around performance and availability/cost of parts.  Just be aware that full, direct sunlight will have SOME effect on the range of your system.

Bottom line - the TSOPs provide a very cost- effective and readily available solution for use in DIY Laser Tag systems, and the newer TSOP modules are much better than their ancestors.  All of the current hobbyist systems use TSOPs.  Even a few of the high-dollar professional rental systems still use TSOP sensors very successfully, though many have developed custom sensors with much better immunity to the sun.

Old Sensor Design