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Lamp Flasher - Simple photo-sensitive circuit 3V battery supply (added 9/04) |
| Laser Light Detector, 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. ….(designed by David A.
Johnson) |
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Laser Pointer Train Detector - This train detector makes use of hand held laser
pointer devices that are widely available to detect trains over long
distances.(electronic circuit added 7/03) |
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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 connected to either a
multi-meter or an oscilloscope. ….(designed by David A. Johnson) |
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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 idea added 1/05) |
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LDR light/dark activated relay Switch - (electronic circuit added 4/05) |
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LED 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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LED Photodetector - Using the light-emitting diode as the photodetector (circuit
added 6/07) |
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LED senses & displays ambient light intensity - 11/09/06 EDN-Design Ideas: LED
doubles as photosensor and visual indicator of ambient-light intensity.....(design
idea added 05/07) |
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Light Activated Detector Circuit LM393/LM555 - (circuit diagram added 05/06/07) |
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Light Activated Relay (Bowden) - This is same circuit as above with the addition
of a photo resistor to trigger the flip flop instead of a push button. The bias
resistor in series with photo resistor was chosen so that sufficient voltage is
present at the base of the 2N3904 to supply current to the circuit in ambient lighting
conditions...(electronic circuit added 4/05) |
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Light Barrier Detector - (electronic circuit added 10/05) |
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Light Detector Circuit (Mick Devine) - 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. (electronic schematic / circuit added 4/02) |
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Light Detectors With Amibient Light Compensation - These circuits were taken from
a few application notes on infrared remote control devices. They use a current
compensation method to separate the modulated light pulses from ambient light. They
appear to have limited bandwidth and may only work at the 30KHz to 50KHz frequencies
often used by TV and VCR remotes. I have not yet tested the circuits. ….(designed by
David A. Johnson) |
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Light direction sensor - (schematic added 02/09) |
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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 transistor circuit to drive the lamps under test and used
the hobby circuit below to measure the decay time. the hobby circuit was a simple PIN
photo diode connected.... ….(designed by David A. Johnson) |
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Light Pollution Meter - (circuit design added 8/03) |
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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. ….(designed by David A.
Johnson) |
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Light Sensing RF Transmitter - (Tony van Roon's electronic circuit added 7/03) |
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Light Sensitive Alarm Circuit - The circuit detects a sudden shadow falling on the
light-sensor and sounds the bleeper when this happens. The circuit will not respond to
gradual changes in brightness to avoid false alarms. The bleeper sounds for only a
short time to prevent the battery running flat. Normal lighting can be used, but the
circuit will work best if a beam of light ….(design added 08/08) |
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Light Sensor Adapter for Oscilloscope - (electronic circuit added 4/05) |
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Light Sensor With Hysteresis - (Tony van Roon's electronic schematic / circuit
added 4/02) |
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Light Sensor-741 Based - CdS photocell used for light/dark controlled relay (Tony
van Roon's electronic design added 5/02) |
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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 feed them through a flip/flop to produce
a square wave signal. Although the circuit shown is designed for a 5v supply, it
could operate from almost any voltage from 3v to 15v. ….(designed by David A. Johnson) |
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Light/Dark Detector (Aaron Cake) - 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. (circuit / schematic
design added 04/03/02) |
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Light-Sensitive Alarm - The circuit detects a sudden shadow falling on the
light-sensor and sounds the bleeper when this happens. The circuit will not respond to
gradual..... Designed by John Hewes (added 09/05) |
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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. ….(designed by David A. Johnson) |
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Low power 100kHz Light Receiver - By starving a high speed logic inverter for
current, this circuit can produce a sensitive 100KHz light receiver circuit, which is
immune to ambient light, but only drawing 100 microamps from a 3 volt supply.
….(designed by David A. Johnson) |
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LX1970 Visible Light Sensor AN-28 - Application Note 28 from Microsem (app
note added 6/06) |
