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Light Detector - This circuit detects light falling on the Photo-cell (Light Dependent Resistor) to turn on the 555 and create a tone that is delivered to the speaker. Pin 4 must be held below 0.7v to turn the 555 off. Any voltage above 0.7v will activate the circuit. The adjustable sensitivity control is needed__ 555-Timer
Light Detector - This circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network. it is very stable and very sensitive. This hobby circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm. I included a simple JFET post-amplifier with a gain of about 20. . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Light Detector - NOTE: Variable resistor R1 adjusts the light threshold at which the circuit triggers. R1's value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS
4001 IC . Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit. The output device may be a low power piezo buzzer. __ Designed by Mick Devine, UK
Light Detector with High Ambient Light Immunity - This circuit is designed for detecting infrared light modulated at around 40KHz. it’s feedback scheme cancels much of the DC component from ambient light. it’s conversion factor is about 100 millivolts per microwatt of 900nm light.. . . Circuit by Dave Johnson P.E.-July, 2006
Light Intensity Monitor - For an on-going consulting project, I had to determine the light output decay time of different fluorescent lamps. I wanted to know how fast the light from a lamp dropped to a low level, after current was interrupted in the lamp. I used a high voltage . . . Hobby Circuit designed by David Johnson P.E.-April, 2005
Light Monitor Circuit - The circuit below takes advantage of a low power op amp with a “rail to rail” feature. The single resistor R1 defines the light sensitivity of the circuit. The output voltage is directly proportional to the intensity of light striking the small photodiode . . . Hobby Circuit designed by David A. Johnson P.E.-August, 2010
Light Pollution Meter - LED brightness control circuit and a millimeter to compare light levels to LED level __ Designed by Avery Davis
Light Pulse Receiver (2uS) - Although the LF357 is an obsolete part, this circuit gives you an idea how to build a sensitive modulated light detector with high ambient light immunity. The first section uses a 100mH inductor as an efficient photodiode current to voltage conversion circuit . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2002
Light Pulse Receiver + Post Amp - This circuit is designed to detect very weak light pulses lasting 1uS. it uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity. A post voltage amplifier is included with a gain of about X20. . . Circuit by Dave Johnson P.E.-March, 1999
Light Receiver 30Khz Amp - This circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode. The circuit draws only about 330uA from a 6v battery . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002
Light Receiver Front-End Circuit - if you want even more sensitivity than the above circuit, try this design. When used with a one centimeter square photodiode, you can achieve a range of several hundred feet with a standard TV or VCR remote control module. Note: The LF357 operational amplifier is no longer available this circuit is for reference only. . . . Hobby Circuit designed by David Johnson P.E.-March, 1999
Light Receiver Works from 1Khz to Over 70Mhz - 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 Johnson P.E.-June, 2000
Light Receiver-10MHz to 20MHz - Light power to volts conversion = APPROX.15mV per microwatt at 850nM . . . Hobby Circuit designed by David Johnson P.E.-July, 2006
Light Sensing RF Transmitter - This transmitter is very simiilar to the Simplest RF Transmitter. The only difference being the photoresistor placed in series with R1. This could also be a thermistor or other variablwe resistance sensor. __ Designed by Tony van Roon VA3AVR
Light Sensor Adapter for Oscilloscope - This circuit is a simple visible light or IR detector for testing any equipment which outputs light. The circuit can be also used for measuring ambient light levels. This circuit is based on one photodiode which is used in photocell mode so that the photodiode generates a voltage and current signal when it get light. __ Designed by Tomi Engdahl
Light Sensor with Hysteresis - it is quite a simple circuit but rather more effective than the one using the 741. it uses a simple comparator LM311 as the mater piece. This comparator is powered from a +12V DC supply and does not require negative supply to work efficiently. __ Designed by Frank Rivard
Light Sensor-741 Based - The circuit as shown act as a light sensor. Under normal conditions the resistance of the LDR is high, keeping pin 2 low. When light falls onto the LDR the resistance drops to a couple hundred ohms and triggers pin 2 high which biases the base of Q1 via pin 6 and R4 and in turn activates the relay __ Designed by Tony van Roon VA3AVR
Light to Frequency Converter - This circuit uses a CMOS
version of the classic 555 timer, to form a light intensity to frequency converter. A small PIN photo diode is used as the light detector. The pulses produced are short, so in some applications you may want to stretch them or . . . Hobby Circuit designed by David Johnson P.E.-May, 2008
Light to Frequency Converter - Fout = –1.4kHz per microampere of photo diode current, iPD. The LTC6990 is a precision silicon oscillator with a programmable frequency range of 488Hz to 2MHz. it can be used as a fixed-frequency or voltage-controlled oscillator (VCO). The LTC6990 is part of the TimerBlox family of versatile silicon timing devices. A single__ Linear Technology/Analog Devices App Note, Jun 16th 2010
Light/Dark Detector drives a relay - This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light. __ Designed by Aaron Cake
Lightening Detector - A VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in synchrony with the lightning bolts indicating the proximity and intensity of the storm. it has a superior RF section with a single resonance near 300kHz and plenty of sensitivity. The antenna is a telescopic antenna that extends to two or three feet __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Lightning Activated Camera Shutter Trigger - This circuit is used to trigger a camera's electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light. __ Designed by G. Forrest Cook
Lightning Detector - Egor! Come quick! A storm approaches! Here is a VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in sychrony with the lightning bolts indicating the proximity and intensity of the storm. Figure 1 shows the simple receiver which consists of a tuned amplifier driving a modified flasher circuit. __ Designed by Kyriakos Kontakos
Lightning Simulator - This little simulator generates short pulses at a few Hz rate and is heLPFul in designing and testing lightning detector circuits like the one at the top of the page. The output is connected to a shielded audio cable with an RCA type connector. The other end of the cable is connected to the antenna of the lightning detector through a 10 pF capacitor (not shown). The shield of the audio cable is connected to the detector's ground. The 10 pF allows the lightning detector's tuned circuit to ring and the amplitude of the ring may be observed on the collector of Q1. The circuit is built into a Home Depot gift certificate can. The circuit board slides into two card guides glued to the ends of the can. Any type of construction will probably work fine, but a metal can is recommended to keep the pulses "contained. " __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Light-Operated Doorbell - Light-dependent switches are used in automatic hand-dryers and flushers in toilets. Here is a simple light-operated switch that works in normal light also. You can affix it on the main door...__ Electronics Projects for You
Light-Operated Internal Door Latch - Using this light-operated circuit, you can close or open the door of your room remotely from your bed. You just have to focus the torchlight on the light-dependent resistor of the...__ Electronics Projects for You
Lights Control for Model Cars - NOTE: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010
Lights timer - Automatically turn off the lights after 10 minutes. if you often forget to turn off the lights outside or at different places in the house, this circuit can be practical for you. it can control two independent light switches with different turn off times. Press the button once and the light turns on for the preset time. Press again, and the light remains on forever. Press for the third time, and the light turns off __ Designed by Peter Jakab
Light-Sensitive Alarm - The circuit detects a sudden shadow falling on a light-sensor and sounds a bleeper for a short time (adjustable). Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound __ Designed by John Hewes
Light-Sensitive Fire Alarm - This light-sensitive fire alarm circuit is extremely sensitive, low-cost and easy to assemble even by a beginner. it uses infrared photo transistor as fire sensor. Circuit and working Circuit diagram of the light-sensitive...__ Electronics Projects for You
Line-Powered Xenon Flash Transmitter - This line powered xenon flash circuit drives a small camera type flash tube. it has an optical isolator to allow the flash to be safely triggered from some remote device. A flash rate of 2Hz is possible with the circuit. . . Circuit by David Johnson P.E.-June, 2000
LM741 Light Dark Sensor - Build a light/dark sensing circuit to automatically turn on/off lights and other devices. __ Designed by REUK-Renewable Energy UK website
Low Power 40KHz Light Detector - This circuit is designed for detecting infrared light modulated at around 40KHz. it’s feedback scheme cancels much of the DC component from ambient light. it’s conversion factor is about 100 millivolts per microwatt of 900nm light.. . . Circuit by David A. Johnson P.E.-July, 2006
Low Power Amp Monitors Light - The circuit below takes advantage of a low power op amp with a “rail to rail” feature. The single resistor R1 defines the light sensitivity of the circuit. The output voltage is directly proportional to the intensity of light striking the small photodiode. . . Circuit by David A. Johnson P.E.-August, 2010
Low-Cost Dusk-Dawn Controller - This dusk-dawn controller is built around a light-dependent resistor among other components. The common battery supply is used for operating the circuit as well as for load, that is, for power LED/small inverter circuit. Resistors work as voltage divider and current limiter in the circuit. LEDs are used as circuit deactivation indicator. An n-channel MOSFET is used for the switching action of an LED light.__ Electronics Projects for You
Low-Cost Night Lamp - This simple, low-cost night lamp automatically activates at night and deactivates in the daytime. it incorporates battery charging circuit with protection against over-charging and deep-discharge. The circuit comprises three sections, namely, power...__ Electronics Projects for You
Low-power optical interrupter - 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. . . Circuit by David Johnson P.E.-June, 2000 |
