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High Ambient Light Immunity Light Detector - The circuit below was designed to turn on an external 12v relay, whenever it detects light from a nearby LED light source, modulated at 40KHz to 50KHz. This circuit was originally designed to operate from a fast moving vehicle . . . Hobby Circuit designed by David Johnson P.E.-December, 2004
High Ambient Light Immunity with a 40Khz Light Detector - The circuit below was designed to turn on an external 12v relay, whenever it detects light from a nearby LED light source, modulated at 40KHz to 50KHz. This circuit was originally designed to operate from a fast moving vehicle . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006
High Speed Light Detector from FET Input - This circuit is yet another design that converts current from a PIN photo diode to a voltage. it has a bandwidth that extends beyond 50MHz . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000
High-speed 75MHz light receiver - This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response. it is designed around a PIN photo diode that is packaged for use with plastic optical fibers. it can be used as an optical fiber receiver. By using the open end of the optical fiber it can "sniff" out any modulated light signals. . . Circuit by David A. Johnson P.E.-June, 2000
Honeybee Counter - I designed a circuit similar to this one a long time ago to help a beekeeper count the number of bees going into or out of a hive. The low power circuit uses a slotted opto-sensor to detect the passing bees. The circuit advances an electronic counting. . . Circuit by David A. Johnson P.E.-July, 2000
Ideal Blocking Diode Circuit for Photovoltaic Solar Panels - Most photovoltaic solar panels are used to charge a battery during the daytime. Nearly all panels come equipped with a blocking diode. The diode prevents DC current from flowing backwards from the battery bank into the panel at night. The usual blocking. . . Circuit by Dave Johnson P.E.-March, 2011
Ideal Diode for PV Panels - Solar panels usually include a diode at their outputs. The diode prevents current from back feeding into the panel at night from the battery being charged by the panel. But, this diode does waste some power and does reduce the available panel voltage . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2011
Ideal Diode Function - Most photovoltaic solar panels are used to charge a battery during the daytime. Nearly all panels come equipped with a blocking diode. The diode prevents DC current from flowing backwards from the battery bank into the panel at night. The usual blocking . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2008
Image-Capture System Uses USB & Labview - 24-Jun-10 EDN Design Ideas: Capturing and processing graphical images requires manipulating data into a form that you can use. This design idea describes an imaging system using a USB (Universal Serial Bus) image-capturing system that uses OmniVision’s 640×480-pixel, 8-bit-color OV7660 image sensor. The CY7C68013A-128AXC from Cypress Semiconductor provide as a USB interface between a PC and the image sensor (Figure 1). The control software is written in LabView from National instruments Design by Chien-Hung Chen and Po-Jui Chen, National Applied Research Laboratories, Hsinchu, Taiwan
Implement Photovoltaic-Module Simulator - 04/07/11 EDN Design Ideas: Use combinations of diodes to simulate photovoltaic cells. Electronics engineers often use photovoltaic-module simulators to test dc/dc-power converters, inverters, or MPPT (maximum-power-point-tracking) -control techniques. The use of these simulators lets you work in the laboratory with predefined photovoltaic conditions, thus avoiding the drawbacks of real photovoltaic modules. Various commercial simulators are available, but they are often expensive. Design by José M Blanes and Ausiàs Garrigós, University Miguel Hernández, Elche, Spain
Improve Response Time of a Photo Transistor Circuit - This page shows different ways to improve the response time of a photo transistor circuit . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2010
Improved Solar LED Spot Light - Nearly all the Chinese made solar powered LED lights I see being sold at Lowe's and Home Depot home improvement centers are poorly designed. Their solar panels and battery packs are all undersized. The light from their Chinese made LEDs fade rapidly and the devices never make it through a complete night before the light dies. . . Circuit by David A. Johnson P.E.-February, 2013
Improved Solar Path Light - The circuit below was designed to replace the guts of an existing path light assembly with one which has a much better performance. I suggest using a quality 10 cell solar panel with at least a 4 square inch area. Buy a panel with solar panels that fills . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2011
Indicates when it is Time to Dust - I have used the circuit below for many different applications, which require ultra low power drain. it uses a single CA4013 flip/flop. One section forms a pulse generator. The generator produces 100uS pulses at a rate of about 1 per secondCircuit Solution by Dave Johnson P.E.-May, 2006
Indicates when it is Time to Dust - I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough. I have not yet built and tested this circuit completely but in concept it should work. . . Circuit by David A. Johnson P.E.-June, 2000
Infrared Detector - This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transistor works as an amplifier which feeds current to the led. When this circuit detects IR or light, the LED is on. So you need to shield the phototransistor from ambient light if you don't want to do your tests in the dark. The best way __ Designed by Lennie Zink
Infrared Remote Extender Circuit - This circuit is designed to be placed directly in front of a standard TV or VCR remote. The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Inspect Solar Cells Without a Microscope - 26-Nov-09 EDN Design Ideas: Use a short-wave infrared camera to capture the image of an entire wafer Design by Chun-Fu Lin and Tai-Shan Liao, National Applied Research Laboratories, Hsinchu, Taiwan
It's Time to Dust Indicator - I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough. I have not yet built and tested this circuit completely but in concept it should work . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
Lamp Flasher - This circuit adopts the rather unusual Bowes/White emitter coupled multivibrator circuit. The oscillation frequency is about 1Hz and is set by C1 value. __ Contact Flavio Dellepiane, fladello @ tin.it
Laser Burst Light Detector - This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen. it was used as part of a firearm training system. it generates a 100mS output pulse whenever it detects a 3ms to 5ms laser burst, modulated at 40KHz. it is very sensitive and could be modified for long range laser communications. . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
Laser Light Detyector-10Mhz to 20Mhz - This circuit was originally designed to detect laser light pulses for an optical Ethernet communications system. it has good ambient light immunity . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Laser/LED Light Output Intensity Meter - This circuit uses a large 1cm X 1cm silicon PIN photo diode and a transimpedance amplifier to measure the light power output of infrared and visible LEDs and laser diodes. it can be modified to produce almost any milliwatts to volts scale factor. it can be. . . Circuit by David Johnson P.E.-July, 2000
Latching light Detector is frugal with power & parts - 09/26/02 EDN Design Ideas: This idea demonstrates three uses for the humble LED. The circuit in Figure 1a forms a simple light detector that latches and turns on an LED when the ambient light exceeds a preset limit determined by potentiometer P1. LED D1 is both the indicator and the light detector. All junction diodes exhibit some degree of photosensitivity Design by Anthony Smith, Scitech, Biddenham, Bedfordshire, UK
LDR light/dark activated relay Switch - We wanted to do a light/dark switch as a kit. But we found there were several types of basic circuit. This is one type of circuit. Two other types may be found in Kits 79B and 79C. __ Designed by R. M. Marston
LED as Light Sensor - Usually light-dependent resistors (LDRs) and photodiodes are used as light sensors to activate or deactivate circuits based on the presence or absence of light. But a common transparent LED can also...__ Electronics Projects for You
LED Photo Sensor - 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 __ Designed by Bill Bowden
LED senses & displays Ambient light intensity - 09/05/07 EDN-Video Design ideas - Explains how an LED can double as a photosensor and a visual indicator of ambient-light intensity Design by Dhananjay V Gadre of India's Netaji Subhas Institute of Technology
LED senses & displays Ambient-light intensity - 11/09/06 EDN Design Ideas: LED doubles as photosensor and visual indicator of ambient-light intensity Design by Dhananjay V Gadre and Sheetal Vashist, ECE Division, Netaji Subhas Institute of Technology, New Delhi, India
LED/Laser Light Output Intensity Meter - This circuit uses a large 1cm X 1cm silicon PIN photo diode and a transimpedance amplifier to measure the light power output of infrared and visible LEDs and laser diodes. it can be modified to produce almost any milliwatts to volts scale factor. it can b . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2000
LEDs used as Photodiodes - 11/18/10 EDN Design Ideas: Ambient light changes an LEDs resistance, making it act like a photodiode. [Design idea by Raju R Baddi, Raman Research institute, Bangalore, india Design by Raju R Baddi, Raman Research Institute, Bangalore, India |
