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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 Johnson P.E., 06/04/00]
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., 01/01/98]
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., 06/04/00]
Optical RFID Test Circuit - I designed this test the concept of using light techniques to send
identification data instead of RF. A more detailed discussion on this scheme can be found in the Imagineered
new products section . . . [Circuit by David A. Johnson P.E., 02/11/02]
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. . . [Copyright © 1998 Wenzel
Associates, Inc.]
Photo Detector Circuits (E+F)
- Light activated detector circuit
for model train. . . [Designed by Rob Paisley]
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. . . [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., 11/01/10]
Photocell Activated Toys - Sensor circuitry out of a very sensitive children's photoelectric Room
Gaurd toy. The original toy would talk and make alarm sounds, whenever an intruder walked by or cast any kind
of shadow onto the photocell. This circuit has immunity to battery voltage transients. . . [Reverse
engineered schematic by Stepan Novotill]
Photo-Detector Circuit (LM324 /
LM556) - Light activated detector
circuit for model train. . . [Designed by Rob Paisley]
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., 03/06/11]
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. . . [Andy Collison]
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. . . . [Designed by Rob Paisley]
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., 10/01/06]
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., 03/06/11]
Quadruple Infrared Proximity Detectors
Circuit - The circuits on this page
are for an Infrared - Proximity Detector using the Vishay Electronics - TSOP4830 "IR Receiver Modules for
Remote Control Systems"Scroll down to find this one. . . . [from Rob Paisley's Model Train web site]
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