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Modulated Light Monitor - This battery powered circuit will work from DC to
500KHz. It is designed to connect to an oscilloscope to monitor the light level
changes and modulated signals. ….(designed by David A. Johnson) |
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Optical Design Of Ambient Light Sensor AN-32 - Application Note 32 from Microsem
(app note added 6/06) |
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Optical Interrupter Draws Microamps - This circuit is great for battery-powered
systems that use slotted type optical interrupters. It draws only 10uA from a 3v
battery that should allow up to 5 years of operation from a lithium battery.
….(designed by David A. Johnson) |
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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. ….(designed by David
A. Johnson) |
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Optical Sensorneeds no tweaking - 06/13/02 EDN-Design Ideas: The transfer gain of
optical sensors spans a 16-to-1 ratio because of variations in the LED,
phototransistor, ambient temperature, and optical path. The wide transfer-gain
variation complicates output-resistor selection in dc-coupled circuits. You must size
the output resistor to prevent high transfer.....(design idea added 1/05) |
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Photo Sensor Circuit - Here's a circuit that takes advantage of the photo-voltaic
voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor
and then applied to the inverting input of an op-amp with a gain of about 20. This
produces a change of about 5 volts at the output from darkness to bright light. The
100K potentiometer can be set so that the output is around 7 volts in darkness and
falls to about 2 volts in bright light. (schematic added 05/09) |
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Photo Transistor Interface Circuits - This page shows different ways to improve
the response time of a photo transistor circuit. ….(designed by David A.
Johnson) |
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Photodetector Sorts Objects - 03/04/99 EDN-Design Ideas: Most object-sensing
systemshave problems detecting the presence of an object. The system in Figure 1 uses
an oscillator to ease detection problems and allow sorting. The oscillator reduces
power dissipation in the photodiode by operating the diode at 50% duty cycle. The
oscillator.....(design idea added 8/03) |
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Photovoltaic Switch disables unused LEDs - 03/18/04 EDN-Design Ideas: In many
applications, it's desirable to disable LEDs used for system verification. Many
options are available for the disabling function, including manual SPST (single-pole
single-throw)switches, enhancement- and depletion-mode MOSFETs, bipolar-junction
transistors, and JFETs. The circuit in Figure 1 automatically disables the LEDs when a
mechanical housing encloses the circuit card, thereby.....(design idea added 1/05) |
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Porch Light Switch - (electronic design added 6/07) |
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Power Supply 5v Solar - This project uses the 1.2v rechargeable battery and solar
panel from a Solar Garden Light. These lights can be bought for less than $5.00 in
most $2.00 shops or similar shops that sell general household items diagram….(circuit
added 05/07) |
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Pulsed Sensor Extends Battery Life - 01/01/98 EDN-Design Ideas: (design idea added
3/03) |
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Red LEDs function as light sensors - 03/20/08 EDN-Design Ideas: You can build
simple LED illuminators using the red LED to sense ambient-light level.....(design
idea added 03/08) |
