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Night Light - The two transistors are used as a direct coupled
switch, Adam used 2SC711 but any general purpose transistor will do e.g.
2N3904, BC109C. The CDS photocell, type ORP12 is normally illuminated,
therefore its resistance is low. The 50k control, the 1k resistor and the
photocell form a potential divider which biases the first transistor.
This transistor is on, its collector being held low, turns the last
transistor and hence lamp and relay off..... |
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Octuple 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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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. (schematic added 05/09) |
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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] |
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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] |
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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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RF Transmitter Light Sensing - Photo sensor is placed in series with a
resistor…. [Tony van Roon's circuit] |
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Screamer Siren - Light Controlled - This circuit will produce an
ear-piercing scream, depending on the amount of light being detected by the Light
Dependent Resistor. |
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Sensing Light with a Programmable Gain Amplifier - Microchip Application
Note Published 28-Mar-03 (app note added 2/06) |
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Simple light Sensoradapter for Oscilloscope - (electronic circuit added
4/05) |
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Simple Photodetector Circuit - I´ve designed this simple circuit to test a
photodetector. I got the detector from an old 5 1/4" disk drive. If you can get one,
you will find two photodetectorts: one is used to sense the density (double density or
high density)(schematice added 6/07) |
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Sun - Up Alarm - The Sun - Up Alarm can be used to provide a audible alarm
for when the sun comes up or it can be used in a dark area and detect when a light
comes on. It can also be used to detect a light beam, headlights etc. The circuit
works as follows. The phototransistor is very sensitive to light. (Any phototransistor
will work fine).... |
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Sunrise Lamp using 120VAC 60 Watt Lamp - In this circuit, a 120VAC lamp is
slowly illuminated over a approximate 20 minute period. The bridge rectifier supplies
120 DC to the MOSFET and 60 watt lamp. A 6.2K, 5 watt resistor and zener diode is used
to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should
be rated at 200 volts and..... [Bill Bowden's circuit] |
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