|
Modulated Light Receiver Front-End Circuit - 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
Monitor Clear Fluids - This circuit detects when a clear fluid is inside a piece of clear plastic tubing. it can be used for fluid level control and monitoring. . . Circuit by David A. Johnson P.E.-May, 2012
New Lightning Detector - Especially built for the beginner __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Night Lamp From Scrap CFL - Compact fluorescent lamps (CFLs) are available in different shapes and power ratings. These consist of an electronic ballast circuit and a programmable-logic-controlled tubelight. Most CFL manufacturers offer a guarantee of half...__ Electronics Projects for You
Night Lamp-Low-Cost - 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
Night Light - This circuit for an electronic night light was submitted by Adam from Canada. I have provided the notes __ Designed by Andy Collison
Night Light from White LED - As many of you know, I have a pet peeve with poorly made LED night lights. Often, the light from the LED quickly fades, so within months, the light is useless. I have posted several versions of modified night lights using higher quality components. . . Circuit by David A. Johnson P.E.-November, 2008
Night Vision Enhancer - Here is a simple green LED flashlight built around 555 timer IC (IC 1) and powered from a 3V battery pack. Green LED based flashlights are widely used by hunters and others in...__ Electronics Projects for You
Night-Light Uses a Photoresistor to Detect Dusk - 12/15/11 - Design ideas - You can adjust this battery-powered circuit for different levels. Design by Chau Tran, Analog Devices, Malden, MA
Night-Vision Digital Goggle - At night, on highways, the high-intensity light from the headlight of heavy vehicles blinds oncoming light vehicle drivers (bike riders and car drivers) for a moment. This is the main reason...__ Electronics Projects for You
One-Watt White LED Night Light - As many of you know, I have a pet peeve with poorly made LED night lights. Often, the light from the LED quickly fades, so within months, the light is useless. I have posted several versions of modified night lights using higher quality components. This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2008
Operation of Cascode Light Receivers - This page provides a detailed explanation of how the modified cascode light receiver circuit operates. The cascode technique in conjunction with an inductive load provides very high current to voltage conversion as well as very high speed . . . Hobby Circuit designed by David Johnson P.E.-February, 2002
Optical Fiber Receiver-5Mhz Broad Band - This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers. it has a bandwidth from 1KHz to over 5MHz. it is great for experimenting with various modulated . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
Optical Filter using Color Film Negative - This isn’t an electronic circuit but the file shows the curve for an optical filter made from exposed color film. The material blocks most visible light but is very transparent to 880nM infrared light. Kodak 100ASA is exposed to "cool white" fluorescent light for about 5 seconds . . . Hobby Circuit designed by David Johnson P.E.-January, 1998
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. . . Circuit by David A. Johnson P.E.-June, 2000
Optical RFID Test Circuit - I designed this test the concept of using light techniques to send identification data instead of RF.. . . Circuit by David A. Johnson P.E.-February, 2002
Optical sensor needs 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 gains from causing output-stage saturation, but low transfer gains yield low output-voltage sw Design by Ron Mancini, Texas Instruments, Bushnell, FL
Other Optical Sensors - Cadmium-Sulfide photoelectric cells change resistance with changing light levels and are useable over a tremendous illumination range. A simple CdS cell placed in the focal plane of a lens makes a telescopic 'electric eye' that can function at midnight or noon, with the appropriate circuitry. To illustrate the idea, consider the antique from my school days shown below. The box was for a famous cologne and the lens just perfectly projects images onto the photocell __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Photo Meter Assesses Ambient Light - 10/15/12 EDN Design Ideas: When most PN-junction diodes are reverse biased, they will produce a small photovoltaic output as the light level is increased. Most PN-junction diodes can be used as photodiodes. While not optimized for this application, they do work. When the diode is reverse biased, it will produce a small photovoltaic output as the light level is increased. LEDs are particularly suited for this task because their housings are transparent Design by Raju Baddi
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
Photo Transistor interface Circuit - This page shows different ways to improve the response time of a photo transistor circuit. . . Circuit by Dave Johnson P.E.-November, 2010
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 also enables a 50% increase in the noise-filter time constant, and it functions as a timebase to allow object sorting. The oscillator chops the photodiode's bias. The signal the photodetector receives is a square wave; thus, a filter can remove optical noise. You normally need filtering when light shines through fans onto the optical detector. When required, you can place a bandpass filter in series with Q3's output. Design by Alan Erzinger, Harris Semiconductor, Palm Bay, FL
Photovoltaic Solar Panels-Ideal Blocking Diode Circuit - 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 David Johnson P.E.-March, 2011
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 MOS Design by Lance McBride, Monterey Bay Aquarium Research Institute, Moss Landing, CA
Porch Light Switch - This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer. __ Designed by Andy Collinson
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. __ Contact Collin Mitchell
Pulsed Sensor Extends Battery Life - 01/01/98 EDN Design Ideas: Activating the sensor circuit in Figure 1 for 1 sec every 30 minutes lowers its 20-mA supply current to an average of 70 µA. For a battery comprising three AA Duracells, this pulsed operation extends the battery's life to several years. The sensor uses an optocoupler and an iR-emitting diode Design by Terry Millward, Maxim Integrated Products, Reading, UK
PV Solar Cell Test Fixture - This is an illustration of a test fixture, which can be used to test individual solar cells for short circuit current. Using a PIN photo diode and a control circuit, the solar cells can be tested under constant light level conditions . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2006
PV Solar Panels-Ideal Blocking Diode Circuit - 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 Johnson P.E.-March, 2011 |
