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Sensors / Detectors: Light Detectors and Optical Sensors   Page 1
Sensors / Detectors -- Main Page
Light Detectors / Optical Sensors:   #'s      A-C      D-K     L     M-R     S-Z

Last Updated on: Thursday, October 30, 2014 09:22 AM

Circuits Designed by Dave Johnson, P.E. :
  • 10MHz TO 20MHz LASER LIGHT DETECTOR
    This circuit was originally designed to detect laser light pulses for an optical Ethernet communications system. It has good ambient light immunity.

  • 1uS LIGHT PULSE RECEIVER PLUS 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. The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.  Note: The LF357 op amp is no longer available, this circuit is for reference only.
  • 30KHZ LIGHT RECEIVER 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.
  • 30KHZ LIGHT RECEIVER 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.
  • 40KHz LASER BURST 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.
  • 40KHz Light Detector with Sunlight Immunity  NEW
    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. The light transmitter was positioned at a stationary position, while the matching receiver was mounted on the vehicle.  The circuit has high ambient light immunity and in most cases, can operate in direct sunlight.

  • 40KHz 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.
  • 40KHz LIGHT RECEIVER IS IMMUNE TO AMBIENT LIGHT
    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.
  • 40KHz MODULATED 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. The 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.
Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
 
10mhz to 20mhz Laser Light Detector -  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]
1us Light Pulse Receiver Plus 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. The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.  Note: The LF357 op amp is no longer available, this circuit is for reference only.... [Designed by David A. Johnson]
30kHz Light Receiver 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.... [Designed by David A. Johnson]
4 & 8 Infrared-Proximity Detectors (TSOP4830) -  In this circuit the TSOP4830 is used as a sensitive infrared detector that does not require shielding from room lighting. The detector will work under almost any lighting condition from complete darkness to full sunlight….scroll down for this one…. [from Rob Paisley's Model Train web site]
40kHz Laser Burst 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.... [Designed by David A. Johnson]
40kHz Light Detector With High Ambient Light Immunity -  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. The light transmitter was positioned at a stationary position, while the matching receiver was mounted on the vehicle.  The circuit has high ambient light immunity and in most cases, can operate in direct sunlight.... [Designed by David A. Johnson]
40kHz Light Detector with Sunlight Immunity -  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 Corner Circuit by Dave Johnson]
40kHz Light Receiver Amp -  This circuit is similar to number 121 but provides more gain and operates up to 40KHz.  However it draws more power supply current.... [Designed by David A. Johnson]
40kHz Light Receiver Is Immune to Ambient Light -  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.... [Designed by David A. Johnson]
40kHz Modulated 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. The 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.... [Designed by David A. Johnson]
5v Solar Charger -  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 added 05/07)
741 Based Light Sensor -  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.…. [Tony van Roon's circuit]
8 Photo-Detector Circuit -  There are two versions of the "8 Photo-Detector" circuitboard. Circuitboards and parts are available for both versions of this circuit.... [from Rob Paisley's Model Train web site]
9v Powered Xenon Photoflash Controller -   This 9v battery powered circuit is designed for remote control flash needs. A charge control circuit turns off the high voltage generator when the photoflash capacitor is fully charged. A neon lamp is included to indicate when the system is ready to flash. …. [Designed by David A. Johnson]

Light Detectors / Optical Sensors:   #'s      A-C      D-K     L     M-R     S-Z


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