Measuring and Test Circuit

Practical Quad Photo-Detector Circuit

Published:2013/6/6 20:32:00 Author:muriel | Keyword: Practical Quad Photo-Detector Circuit

The next circuit is for a practical 4 photo-detector circuit using an LM339 Quad comparator IC. Although phototransistors are shown, photocells could also be used with the corresponding change in values for resistors R1 through R4. This circuit can also be used for infrared detector circuits as shown above. The values for resistors R7 through R10 can also be changed depending on the required LED current.   (View)

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Infrared Light Photo-Detector Circuit

Published:2013/6/6 20:31:00 Author:muriel | Keyword: Infrared Light , Photo-Detector Circuit

In this circuit the light falling on the phototransistor will be from an Infrared Light Emitting Diode (IrLED) but otherwise it is the same as the phototransistor circuit shown above. When the light falling on the phototransistor (Q1) is blocked, its conductance will decrease and the voltage across Q1 will rise. When the voltage rises above 1/2 of the supply voltage the output of the comparator will turn ON and the LED will be lit.   (View)

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Basic CdS Photocell Detector

Published:2013/6/6 20:31:00 Author:muriel | Keyword: Basic CdS Photocell Detector

In this circuit, when the light falling on the photocell (PC 1) is blocked, its resistance will increase and the voltage across PC 1 will rise. When the voltage rises above 1/2 of the supply voltage the output of the comparator will turn ON and the LED will be lit. Due to wide variations in CdS photocells it is usually best to install the cell and then measure its resistance under normal lighting conditions. A resistor with a value that is approximately 3 to 5 times the measured resistance of the cell is then selected for R1. For example; If the cell resistance is measured at 400 ohms then a 1200 to 2200 ohms resistor would be used. Increasing the value of R1 will cause the sensitivity of the sensor to decrease. This may be necessary when the light falling on the cell is not very strong or shadows can affect the photocell. This circuit can be adapted for use in dark areas by placing a small light above the photocell.   (View)

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Visible Light Photo-Detector Circuits

Published:2013/6/6 20:30:00 Author:muriel | Keyword: Visible Light, Photo-Detector Circuits

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Very Long Range Laser Pointer Detector

Published:2013/6/5 22:05:00 Author:muriel | Keyword: Very Long Range, Laser Pointer Detector

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LEGO® RCX Brick Rechargeable Battery Tester

Published:2013/5/31 2:04:00 Author:muriel | Keyword: LEGO, RCX Brick Rechargeable , Battery Tester

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Optoisolator Type Block Occupancy Detector - LM555 Timer Output Schematic

Published:2013/5/31 2:03:00 Author:muriel | Keyword: Optoisolator Type, Block Occupancy Detector, LM555 Timer Output Schematic

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Optoisolator Type Detector With A LM555 Timer Output

Published:2013/5/31 2:02:00 Author:muriel | Keyword: Optoisolator Type Detector, LM555 Timer Output

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Direction Indicating Detector

Published:2013/5/31 2:02:00 Author:muriel | Keyword: Direction Indicating Detector

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Time Delay Detector

Published:2013/5/31 2:01:00 Author:muriel | Keyword: Time Delay Detector

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Basic Detector

Published:2013/5/31 2:01:00 Author:muriel | Keyword: Basic Detector

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G.P. Block Occupancy Detector - Input Options

Published:2013/5/31 1:59:00 Author:muriel | Keyword: G.P. , Block Occupancy Detector, Input Options

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G.P. Block Occupancy Detector Input Wiring Schematic

Published:2013/5/31 1:59:00 Author:muriel | Keyword: G.P., Block Occupancy Detector, Wiring Schematic

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General Purpose Block Occupancy Detector

Published:2013/5/31 1:58:00 Author:muriel | Keyword: General Purpose , Block Occupancy Detector

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Comparator Based DCC or AC Block Occupancy DetectorSchematic

Published:2013/5/31 1:57:00 Author:muriel | Keyword: DCC , AC Block, Occupancy Detector Schematic

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4 Level Detector Schematic

Published:2013/5/31 1:51:00 Author:muriel | Keyword: 4 Level Detector Schematic

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Voltage Window Detector Circuit

Published:2013/5/31 1:46:00 Author:muriel | Keyword: Voltage Window Detector Circuit

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Proximity Detector

Published:2013/5/28 22:19:00 Author:muriel | Keyword: Proximity Detector

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Infrared - Proximity Detector Circuit 2

Published:2013/5/28 22:17:00 Author:muriel | Keyword: Infrared - Proximity Detector Circuit

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Infrared - Proximity Detector Circuit

Published:2013/5/28 22:17:00 Author:muriel | Keyword: Infrared - Proximity Detector Circuit

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