- MICRO POWER 40KHz BURST
LASER DIODE DRIVER
Some laser tag or simulated combat games can use this circuit to send short
bursts of modulated laser light at the opponent's vest, equipped with a matching
light receiver. The circuit operates from three 1.5v cells (4.5v) that should
provide enough energy for about 200,000 shots.
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- OPTICAL RFID TEST
CIRCUIT
I designed this test the concept of using light techniques to send
identification data instead of RF. A more detailed discussion on this scheme can
be found in the Imagineered new products section.
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- Pigeon
Scarecrow
I have an area on my roof where a large flock of pigeons like to roost.
Their nesting materials and droppings really make a mess. Often there is enough
junk from them that it clogs my roof gutters. Perhaps one way to scare
them away is with a device mounted on the roof near their favorite roosting
spot. The device....
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Reflected Infrared Light Switch
Infrared light
reflected off a finger is used to activate this switch circuit.
Drawing only 30uA from a 3v supply, this circuit
will detect a human finger with a range of about 1 inch. The sensor uses
an inexpensive infrared LED and a matching photo diode.
(added 7/06)
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- Shadow
Activated Motion Detector Circuit
There are many ways one can detect nearby human or object motion. This
circuit demonstrates one way. It detects motion by noting the changes in
the shadow cast by the moving object. The hobby circuit below works quite well
in typical indoor room lighting. I would not recommend its use in direct
sunlight. Two small PIN photodiodes positioned about one inch apart form a
shadow detector. With no shadow cast on the devices, both devices produce
nearly identical current levels. The current is converted to a voltage
with a load resistor in parallel with the photodiode....
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- Short Range
Reflective Object Sensor
Drawing only 30uA from a 3v supply, this circuit will detect a human finger with
a range of about 1 inch. The sensor uses an inexpensive infrared LED and a
matching photo diode.
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