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- 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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- PULSED LED TEST CIRCUIT
This circuit is designed to test visible and infrared LEDs in pulsed mode operations. It can drive the LED with peak currents in excess of 10 amps. A light detector nearby can monitor the response time and intensity of the LED under test.
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- SIMPLE NITROGEN SPARK GENERATOR
Nitrogen or air sparks are very powerful light sources that produce flashes that last only a few nanoseconds. This line powered circuit generates a continuous series of very small sparks across electrodes with a 0.05 inch gap.
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- SINGLE IC FORMS SENSITIVE MODULATED LIGHT RECEIVER
The circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode. Using an unique inductive feedback network, the circuit provides high sensitivity under high ambient light conditions. It is a great circuit when you want to
extend the range of an optical remote control transmitter.
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- VOLTAGE TO FREQUENCY CONVERTER + 1uS LED PULSE DRIVER
This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information. The 10KHz center frequency of the pulse stream is low enough so a
standard infrared LED can emit ten times more light than conventional long pulse techniques. The circuit is described in more detail in the transmitter section of Dave Johnson's Handbook of Optical Through the Air Communications. (this link is off-site)
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- WIDE BAND ZERO CROSS DETECTOR
This circuit was designed to convert a low amplitude 40KHz signal into a clean square wave signal. It will work with inputs as small as 5mv peak to peak or as large as 3 volts peak to peak. The input frequency can range from a few
kilohertz to about 150KHz.
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- XENON LAMP FLASH DETECTOR
This circuit uses a small 2.5mm square photo diode in conjunction with a 100mH coil to detect the short light flashes from a xenon lamp. The coil makes the circuit immune to normal room lights. Its 10mv sensitivity can detect light
flashes from a range of over 100 feet. Reflections from a room’s walls and ceiling is usually enough to trigger the circuit. The entire circuit draws only 3 microamps from a 6 to 9 volt battery.
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