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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] |
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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] |
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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] |
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A 4- to 20-mA loop needs no external power source - 09/13/01
EDN-Design Ideas The simple circuit in Figure 1 uses a
low-current-drain MAX4073H amplifier to sense the current flowing
through a 4- to 20-mA loop. The circuit senses the current through a 1Ω
resistor with a fixed gain of 100 and uses no battery or dc power
supply.... [Design Idea by Shyam Tiwari, Sensors Private Ltd, Gwalior,
India] |
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Air Transparency Monitor, pg 1 - I designed this 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
Fresnel lens at the transmitter end and a matching 12-inch lens with a
PIN photo diode at the receiver. The receiver system was connected to a
weather station and a computer to collect the changes in intensity of
the light flashes under different weather conditions. It has the
potential for a 30+-mile range. I have also used this system to conduct
cloud bounce experiments.... [Designed by David A. Johnson] |
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Air Transparency Monitor, pg 2 - This is Page 2 of the air
transparency monitor receiver circuit.... [Designed by David A. Johnson] |
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AN-1244: Photo-Diode Current-To-Voltage Converters - National
Semiconductor Application Note (app note) |
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AN-240: Wide-Range Current-To-Frequency Converters - National
Semiconductor Application Note (app note) |
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AN-772: A Design & Manufacturing Guide for the Lead Frame Chip Scale
Package - AN-772 Analog Devices Application Notes (app
note) |
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Audio equalizer features transimpedance Q enhancement topology -
6-Mar-08 Issue of EDN A novel op-amp configuration enables a
graphic equalizer with a minimal number of amplifiers.... [Design Idea
by Herminio Martínez, Encarna García, and Eva Vidal, Technical
University of Catalonia, Barcelona, Spain] |
