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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. . . Circuit by Dave Johnson P.E.-July, 2000
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 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 Dave Johnson P.E.-August, 2010
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 David A. Johnson P.E.-March, 1999
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
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 A. 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 A. 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
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 Dave Johnson P.E.-August, 2010
Modulated Light Receiver uses a Single IC
The circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode. Using a unique inductive feedback network, the circuit provides high sensitivity under high ambient light conditions. It is a great circuit when you want to extend the range of an optical remote control transmitter . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
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 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 Dave Johnson P.E.-February, 2002
Photo Transistor interface Circuit
This page shows different ways to improve the response time of a photo transistor circuit. . . Circuit by David Johnson P.E.-November, 2010
Precision Ultra Lower Power Oscillator
This circuit works much like the classic 555 timer, but draws only about 1.5 microamps from a 3 volt battery. It is highly stable under varying temperature and supply voltages. . . Circuit by Dave Johnson P.E.-May, 2000
RFID Test Circuit
I designed this test the concept of using light techniques to send identification data instead of RF. . . . Hobby Circuit designed by David Johnson P.E.-February, 2002
Single IC forms Sensitive Modulated Light Receiver - The circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode. Using a unique inductive feedback network, the circuit provides high sensitivity under high ambient light conditions. It is a great circuit when you want to extend the range of an optical remote control transmitter. . . Circuit by David Johnson P.E.-January, 1900
Ten-Second Ultra Lower Power Oscillator
This circuit works much like the classic 555 timer, but draws only about 1.5 microamps from a 3 volt battery. It is highly stable under varying temperature and supply voltages. . . Circuit by David Johnson P.E.-May, 2000
Ultra Lower Power Oscillator
This circuit works much like the classic 555 timer, but draws only about 1.5 microamps from a 3 volt battery. It is highly stable under varying temperature and supply voltages. . . Circuit by David A. Johnson P.E.-May, 2000
Xenon Flash Receiver-AIR Transparancy Monitor
I designed this receiver circuit many years ago to monitor the quality of a mile long column of air for future optical communications experiments. The transmitter system (circuit 72 below) uses a powerful xenon flash in conjunction with a large 12 inch . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Xenon Flash Receiver-Pg2
This is of the receiver circuit AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Xenon Flash Transmitter-AIR Transparency Monitor
This is the matching transmitter for the above receiver. The transmitter launches powerful 1000-watt light pulses that last about 20 microseconds . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Xenon Lamp Flash Detector Amplifier
This circuit has a very low standby current requirement yet has very high sensitivity toward the light flashes from a xenon lamp. When connected to a flip/flop it can serve as an on on/off Controller. . . Circuit by Dave Johnson P.E.-December, 2004 |
