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	Art's Theremin Page: Infrared Optical Theremin Technical Disclosure
		The current which flows through a phototransistor collector-emitter circuit is primarily related to: 1) the amount of light striking the phototransistor's base-emitter junction, and 2) the amount of current flowing into the phototransistor's base.
		Since the servos only respond to relatively long-term averages of the phototransistor outputs, the changes in output voltage resulting from the reflected modulated light is unaffected by the servos.
		The two distinct voltages present at the phototransistor outputs, one proportional to the ambient light and the other proportional to the reflected modulated light plus ambient light, are alternately presented to the synchronous demodulators.
	home.att.net /~theremin1/irtheremin.htm (1837 words)

	[No title]
		This circuit consists of an infrared sensitive phototransistor which is hooked up to a band pass filter and the output of which is connected to a load resistance such as an alarm or an LED for demonstration purposes.
		Phototransistor was connected in series to a 2k(resistor and a +12V power source for higher response time when signal is present Second section of the circuit was built next.
		Phototransistor: Test that the phototransistor was transmitting the signal that is received from the emitter.
	www.seas.upenn.edu /courses/belab/LabProjects/1997/BE310S97M5R01.doc (2996 words)

	Phototransistor - Wikipedia, the free encyclopedia
		Transistors are amplifiers and in a phototransistor the amplifier gain is controlled by the amount of light striking the device.
		The major use of phototransistors is in non-communications applications using visible (or near visible) light.
		Phototransistors are occasionally built as part of an integrated circuit.
	en.wikipedia.org /wiki/Phototransistor (342 words)

	Day and Night Infrared Detection
		A phototransistor is mounted between the rails so that it is covered by the train as it passes.
		However when the room lights are dimmed or turned off for night operation, under normal conditions the phototransistor would go dark and act as if it was covered by a train and thus give a false detection.
		A 1 Megohm variable resistor connected in series with the phototransistor is used to compensate for the brightness of the room light so that cars with relatively open under frames are accurately detected.
	www.angelfire.com /ab6/userper/daynight.htm (1124 words)

	Quick response solid state relay having a thyristor discharge circuit and a phototransistor - Patent 5293505
		A collector and an emitter of the first phototransistor are connected to the cathode of the photodiode array and a positive gate of the thyristor, respectively.
		An emitter of the phototransistor 19 is connected to the anode 6 of the photodiode array 4, and a collector of the phototransistor 19 is connected to a negative gate of the thyristor 5A.
		An emitter of the phototransistor 10 is connected to a positive gate of the thyristor 5, and a collector of the phototransistor 10 is connected to the cathode 7 of the photodiode array 4.
	www.freepatentsonline.com /5293505.html (2592 words)

	Infrared Across Track Detection
		Infrared phototransistors are also sensitive to visible light and therefore will need to be shielded in someway to prevent the device from being swamped by the rooms lighting.
		If the phototransistor is mounted as shown on the schematic the back of the transistor can be painted fl to prevent room light from entering.
		Making use of phototransistors with lenses built into the case would also be helpful for this particular application and may reduce the number of extra LED's needed to span a given distance.
	www.angelfire.com /ab6/userper/ir_det.htm (1212 words)

	Radio-Electronics.Com :: Photo transistor (Phototransistor)
		Phototransistors are operated in their active regime, although the base connection is left open circuit or disconnected because it is not required.
		A further advantage of all phototransistors when compared to the avalanche photodiode, another device that offers gain, is that the phototransistor has a much lower level of noise.
		One of the main disadvantages of the phototransistor is the fact that it does not have a particularly good high frequency response.
	www.radio-electronics.com /info/data/semicond/phototransistor/photo_transistor.php (954 words)

	Phototransistor
		Although the Phototransistor is still in the experimental stage, Laboratories scientists and engineers expect that, after the necessary development, it may have far-reaching significance in electronics and electrical communication.
		Because of their small size and expected long life, however, together with economies that might reasonably result from mass-production, Phototransistors should find many applications where it is not now practical to use present-day photoelectric devices.
		The Phototransistor is similar in operation to the amplifying Transistor, but it is controlled by light rather than by the electric current of the emitter.
	www.smecc.org /phototransistor.htm (580 words)

	Optoelectronics experiment (Site not responding. Last check: 2007-10-24)
		The phototransistor and the equivalent circuit with a reverse biased diode
		A phototransistor is a transistor whose collector and emitter currents are directly related to the light incident on the base region of the transistor.
		The use of light and phototransistors has many advantages over standard electrical logic circuits since they can be mounted remotely from the device and are safer in situations where an electrical switch may present a fire risk.
	circuits.cf.ac.uk /eLab/opto/opto.htm (948 words)

	Photogate triggers
		The detector is a phototransistor, serving as a variable resistor whose resistance depends on the intensity of detected light.
		As long as the phototransistor is illuminated by the LED, the collector-emitter path of the 2N2222 is open.
		When the light from the emitter (LED) to the phototransistor (PT) is blocked by a moving object, the voltage across the phototransistor increases.
	www.hiviz.com /tools/triggers/triggers3.htm (433 words)

	More on Embedded Microprocessor Solar Targeting System, LDR, phototransistor, solar energy, connecting light sensors, ... (Site not responding. Last check: 2007-10-24)
		Phototransistors and photodiodes may also be used as sensors, but their characteristics are very different from LDRs.
		When light falls on the phototransistor the cpu pin is pulled low, signaling a state change.
		In the analog circuit a 1k-ohm resistor is placed between the cpu pin and the phototransistor creating a minimum low resistance value of 1k.
	phoenixnavigation.com /ptbc/articles/ptbc56.htm (1459 words)

	Physics I Demo Lab Photogate Circuit
		A phototransistor is a transistor in which the base current is created by light shining on the base.
		The phototransistor, on the other hand, is controlled or turned-on by light instead of current.
		Attach the IRLED and the IR Phototransistor to the photogate yoke by soldering.
	www.warren-wilson.edu /~physics/physics1/ActivityGuides/photogate/PHOTGATE.html (946 words)

	CHEM 3325
		Purpose - To use the i/V converter to detect the pulsed radiation reaching the phototransistor of a spectrophotometer.
		Figure 4 is a schematic diagram of a npn phototransistor.
		Since phototransistors have finite response time, when the frequency of the pulsed input signal exceeds the response time of the phototransistor, the output waveform becomes distorted.
	nobel.scas.bcit.ca /chem3325/expt3-1/3-1_phototransistor.htm (590 words)

	Robot Room - Analog Light Sensor Comparator
		This is also a good example of how to use a phototransistor, rather than a cadmium sulfide photocell to detect light.
		For a prototype tachometer project, a microcontroller analyzed a phototransistor and a pair of potentiometers using three built-in analog-to-digital (ADC) converters.
		This phototransistor is sensitive to normal visible light (800 nm).
	www.robotroom.com /Comparator.html (1183 words)

	Photo-Reflectors
		The infrared phototransistor acts as a transistor with the base voltage determined by the amount of light hitting the transistor.
		As shown in the diagram below, the phototransistor is wired in a similar configuration to the voltage divider.
		The amount of light reflected from the emitter into the phototransistor yields a measurement of a surface's reflectance.The photoreflector can be used in robot to follow a path (e.g.
	mechatronics.mech.northwestern.edu /design_ref/sensors/reflectors.html (1407 words)

	EE118 Tape Sensor (Site not responding. Last check: 2007-10-24)
		It consisted of an infrared light emitting diode mounted with an infrared phototransistor such that the light emitted by the diode was received by the phototransistor when it was reflected.
		Thus, when no infrared light was impinging on the phototransistor, the phototransistor was off so the voltage across the output was about equal to the supply voltage.
		Since the maximum current through the phototransistor of the QRB 1134 was rated to be 40mA, a 10K-ohm resistor was chosen to limit the current within its operable range.
	rescomp.stanford.edu /~hpan/fingerroll/tape.html (171 words)

	04.09.98 Design Ideas
		The rise/fall-time rating of the LED is 500 nsec, which is fast enough, but the phototransistor's rise/fall time is 5 µsec for the fastest version and 8 µsec for the slowest with a 1-
		Phototransistors have less favorable dynamic behavior than do photodiodes because, in addition to the collecting and charging processes, phototransistors also experience a delay stemming from the amplification mechanism (Miller effect).
		In Figure 1b's circuit, the phototransistor's internal capacitance and the amplifier's gain bandwidth limit the overall speed.
	www.edn.com /archives/1998/040998/08di.htm (2801 words)

	Phototransistor circuit: (Site not responding. Last check: 2007-10-24)
		This circuit produces a DC output based on the intensity of an oscillating IR signal detected by a phototransistor.
		It was experimentally determined that the current coming from phototransistor when the IR beacon was 5’ away was approximately 3 mA.
		This capacitor and resistor form a high-pass filter that removes the DC component of the input from the phototransistor.
	design.stanford.edu /Courses/me118/pictures/Win02Projects/Evil_Monkey/me118/circuits.html (311 words)

	How It Works: Motor With Optical Control (Site not responding. Last check: 2007-10-24)
		Optointerrupters supplied with the kit (or sold as a separate part) come with a 270 Ohm resistor which is suitable for voltages in the range from 3 to 6V.
		Phototransistors are specially designed transistors with the base region exposed.
		When there is no light the phototransistor is closed and does not allow a collector-emitter current to go through.
	members.tripod.com /simplemotor/oimotor.htm (671 words)

	Phototransistor and IRED Applications (Site not responding. Last check: 2007-10-24)
		Phototransistors are solid state light detectors that possess internal gain.
		Phototransistors can be used as ambient light detectors.
		When used with a controllable light source, typically and LED, they are often employed as the detector element for optoisolators and transmissive or reflective optical switches.
	www.engr.udayton.edu /faculty/jloomis/ece445/topics/egginc/pt_app.html (347 words)

	instructables : Tamiya 72004 worm gearbox speed sensor
		For a reflective sensor a disc with alternating fl and white segments is attached to the motor or somewhere along the drive train.
		An LED (red or infra-red) shines a light onto the disc and a photodiode or phototransistor detects the difference between the light and dark segments by the amount of LED light reflected as the motor turns.
		For this project I realised I needed as many pulses as possible, but it would have been difficult to install an LED and phototransistor next to the motor shaft, so I was fortunate to have discovered the tiny slotted opto-switch in a floppy drive.
	www.instructables.com /id/E7Q9FHDWKUEQHO98Z4/?ALLSTEPS (1742 words)

	How Phototransistors Operate (Site not responding. Last check: 2007-10-24)
		Their goal is to maximize the signal-to-noise ratio, by using an emitter with the best match to the phototransistor response.
		The diagram above illustrates the frequency response of silicon phototransistor junctions, along with the spectral output of an infrared LED.
		The actual operation of a phototransistor depends on the biasing arrangement and light frequency.
	www.oz.net /~coilgun/theory/phototransistors.htm (524 words)

	Phototransistor Manufacturers On B2BManufactures.Com from China & Taiwan Phototransistor Manufacturers, Suppliers & ...
		Phototransistor Manufacturers - Jiann Wa Electronics Co., Ltd.
		Phototransistor Manufacturers - Wei Dien Intl Trading Co., Ltd.
		Phototransistor Manufacturers - Unity Opto Technology Co., Ltd.
	www.manufacturers.com.tw /electronics/phototransistor-manufacturers.html (631 words)

	Robot Room - Bugdozer's Line Detectors
		Phototransistors react much more quickly than do cadmium-sulfide photocells.
		Which phototransistors light up, how much they light up, and the order in which they light up, is used to determine the direction and method (pivot or spin) of turning around.
		Each phototransistor has a resistor (22 kilohms) as a voltage divider.
	www.robotroom.com /BugdozerLines.html (706 words)

	Electronic Parts for your IJ
		That is, the flat edge of the phototransistor goes in the hole furthest away from the hole that has the little notch drawn by it on the circuit board.
		Phototransistor: Radio Shack, Digikey (PN102-ND) or you can send me a few bucks and I can send you the Radio Shack part if you have no other means of getting this part locally.
		We MAY find out that we have to replace BOTH the LED and the phototransistor with the Radio Shack replacements to get it to work since the Radio Shack parts are probably designed to work with each other (the frequency of the infrared light waves might be matched for both parts).
	www.pinballrebel.com /game/pins/ij2/shop/Parts.htm (1243 words)

	ELEC 242 Lab - Experiment 2.1
		There are three components in your parts kit with very similar appearances, but very different functions: the photodiode, phototransistor, and the high-brightness LED.
		Here's how to tell them apart: The photodiode has a flat topped package, the chip in the phototransistor is mounted on a flat pedestal, and the chip in the high-brightness LED is mounted in a bowl-shaped reflector.
		Plug the phototransistor into the 3-pin connector on the other end, connecting the long lead (emitter) to the pin with the white stripe and the short lead (collector) to the center pin.
	www-ece.rice.edu /~jdw/242_lab2/exp2.1.html (688 words)

	Embedded.com - Exploring optical and magnetic sensors
		The phototransistor in a reflective sensor picks up reflected light from whatever is in front of the switch.
		The amount of current generated in the phototransistor collector for a given current through the LED is called the current transfer ratio (CTR).
		To ensure that the phototransistor saturates, the value of the pullup resistor is limited.
	www.embedded.com /story/OEG20030617S0025 (3271 words)

	MiniSumo.org.uk: Phototransistor Edge Detection
		The phototransistor works like a transistor but the base current comes from an integral photodiode so that we need only connect the collector and emitter of the transistor.
		It should be noted that this circuit will tend towards a fl responce as the phototransistor is moved away from the detectable surface.
		Ideally the phototransistor should be mounted rigidly at the optimum distance from the surface, as per the data sheet - 2.79mm in this case.
	www.er-online.co.uk /minisumo/EdgeDetection.php (1040 words)

	ePanorama.net :: View topic - heat-detecting phototransistor?
		Is there such a thing as a phototransistor
		Posted: Sat Dec 09, 2006 6:04 pm Post subject: Re: heat-detecting phototransistor?
		I know it's not much help, but they used to be available.
	www.epanorama.net /phpBB2/viewtopic.php?t=42297 (377 words)

	Phototransistor Manufacturers & Suppliers (Site not responding. Last check: 2007-10-24)
		Phototransistors manufacturers or related Plug, Jack & Socket manufacturers
		Phototransistor Products: Source for Phototransistor manufacturers at Global Sources.
		The featured China Phototransistor manufacturers and featured Taiwan Phototransistor manufacturers listed here are sourced by the Global Sources team of industry experts.
	www.globalsources.com /manufacturers/Phototransistor.html (390 words)

	Phototransistors Information \| Business.com
		Home » Directory » Electronics & Semiconductors » Optoelectronics »; Phototransistors
		Supplies a broad range of optical sensing technologies, including phototransistors.
		Supplier of highly integrated, complementary metal oxide semiconductor (CMOS) image sensors and companion processor integrated circuits for digital cameras.
	rd.business.com /index.asp?epm=s.1&bdcq=Phototransistor&bdcr=1&bdcu=http://www.business.com/directory/electronics_and_semiconductors/optoelectronics/phototransistors/index.asp?partner=2662601&bdcp=&partner=2662601&bdcs=nwuuid-2662601-1C4B8152-363F-E7CE-B893-2985E4685F64-ym (117 words)

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