Infrared Emitter & Detector

This circuit have applied to line detection of robot project, Good match between the transmitter and the detector is important for proper operation, especially if the hole is large.

Circuit diagram :

Infrared Emitter & Detector Circuit Diagram

Robot with a simple object or obstacle detection. Infrared Transmitter detector pair sensors are relatively easy to implement, although involved some degree of testing and calibration in order to make correct. They can for the impediment, motion detection, transmitters, encoders are used, and the color detection.

This can be done with a piece of rope stretched between and in accordance with LED and phototransistor. A length of stiff wire or plugs can be used to set the alignment. Another method that can be used for long distances is a laser pointer shone through a hole.

Source / detector alignment method The transmitter can be mounted above the track with the phototransistor placed between the rails in places like hidden deposits. Place the transmitter and the detector at an angle would again be useful.

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IR (Infrared) Detector

Men in particular enjoy the convenience of television remote controls – often to the annoyance of their female partners. Men apparently want to know what they’re missing when the TV is tuned to a particular program, so they like to keep zapping to other channels. With the remote control in their hands, they feel like they are the lord and master of the TV set. They are thus completely at a loss if the remote control doesn’t work properly. There are many reasons why a remote control unit can malfunction, such as defective IR receiver in the TV set, a defect in the remote control, or empty batteries. Here a tester that can determine whether the remote control unit still emits an IR signal can come in handy. If you want to keep the IR reins firmly in hand, you can build your own IR detector.

Circuit diagram:

Infrared Detector Circuit Diagram

Circuit description:

If you have a few remote control units around the house, you’ll appreciate this little circuit. The LED clearly indicates whether the remote control unit actually emits an IR signal when you press one of the buttons on the unit. The circuit uses a photo-diode (D1) to sense the infrared light emitted by the remote control unit (if it is working properly). The plastic package of this diode acts as an IR filter that is only transparent to invisible light with a wavelength of 950 nm.
Although there are probably some remote control units that use IR diodes operating at a different wavelength, the circuit has enough sensitivity to detect them as well. If enough light falls on photo-diode D1, an electrical current will flow through the diode. In fact, what happens is that the leakage current increases, since photo-diodes are usually operated in reverse-biased mode (as is the case here). If the current is large enough, transistor T1 conducts and causes LED D2 to light up.

If LED D2 remains dark, this means the remote control unit is not producing any IR light. This can be due to an empty battery (or batteries) or a fault in the internal circuitry. Pay careful attention to the polarization of the photo-diode when wiring it into the circuit. The cathode is clearly marked by a special pin. For LED D2, use a low-current type that can handle a current of at least 7 mA. The detector can be powered by a pair of 1.5-V penlight cells connected in series.

Copyright : Elektor Electronics 12-2006

Source : www.extremecircuits.net

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Infrared Fire-Cracker Igniter Circuit

Firecrackers are normally ignited by using a matchstick or a candle. You have to run away quickly after igniting the fuse of the firecracker. This method of igniting firecracker is unsafe, because the danger of the firecracker bursting before you reach a safe distance is always there. The device described here uses remote control, usually used with TV receivers or CD players, to burst the fire-cracker. Thus the firecracker can be ignited from a safe distance using the circuit described below in conjunction with the remote control. In the diagram shown here, normally the output of IC1 is low and green LED2 is ‘on’ and the red LED3 ‘off.’ This indicates that the circuit is ready for use. When any key on the remote control is pressed, output pin 3 of IRX1 (IR receiver module TSOP1738) goes low. This output is connected to pin 2 of IC1 via LED1 and resistor R4 to trigger the monostable operation of IC1. The output of IC1 remains high for a period equal to 1.1×R2×C2. With the values of the components given in the circuit diagram here, the period works out to 3.5 seconds approximately.

Circuit diagram:

Infrared Fire-Cracker Igniter Circuit Diagram

This activates relay RL1 and red LED3 glows and green LED2 turns off. ‘On’ state of red LED3 indicates that the firecracker is about to burst. R7 is a small part of the element of an electric heater (220V, 1000W), which is kept away from the electronic circuit and connected to the relay contacts through a thick electric cable. The resistance value of short length of the heater element (R7) is 3 to 3.5 ohms. A current of around 4 amperes flows through it when connected to a 12V battery. Flow of 4A current through R7 for 3.5 seconds makes it red hot, which ignites the fire-cracker. The circuit is powered by a 12V, 7AH battery. IC2 provides about 9V for the operation of the circuit. The circuit should be housed in a metallic cabinet to prevent it from being damaged by bursting of the firecracker. The IR receiver and the two LEDs should be fixed on the front panel of the cabinet. Wiring and relay used in the circuit should be chosen such that they are able to carry more than 5 amperes of current.

Author: Pardeep Vasudeva - Copyright: EFY Mag

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Long-Range IR Transmitter

Most of the IR remotes work reliably within a range of 5 metres. The circuit complexity increases if you design the IR transmitter for reliable operation over a longer range, say, 10 metres. To double the range from 5 metres to 10 metres, you need to increase the transmitted power four times. If you wish to real i se a highly directional IR beam (very narrow beam), you can suitably use an IR laser pointer as the IR signal source. The laser pointer is readily available in the market. However, with a very narrow beam from the laser pointer, you have to take extra care, lest a small jerk to the gadget may change the beam orientation and cause loss of contact.

Here is a simple circuit that will give you a pretty long range. It uses three infrared transmitting LEDs (IR1 through IR3) in series to increase the radiated power. Further, to increase the directivity and so also the power density, you may assemble the IR LEDs inside the reflector of a torch. For increasing the circuit efficiency, a MOSFET (BS170) has been used, which acts as a switch and thus reif a transistor were used. To avoid any dip during its ‘on’/‘off’ operations, a 100µF reservoir capacitor C2 is used across the battery supply. Its advantage will be more obvious when the IR transmitter is powered by ordinary batteries.

Circuit diagram:

Long-Range IR Transmitter Circuit Diagram

Capacitor C2 supplies extra charge during ‘switching on’ operations. As the MOSFET exhibits large capacitance across gate-source terminals, a special drive arrangement has been made using npn-pnp Darl ington pair of BC547 and BC557 (as emitter followers), to avoid distortion of the gate drive input. Data (CMOS-compatible) to be transmitted is used for modulating the 38 kHz frequency generated by CD4047 (IC1). However, in the circuit shown here, tactile switch S1 has been used for modulating and transmitting the IR signal. Assemble the circuit on a general-purpose PCB. Use switch S2 for power ‘on’/‘off’ control. Commercially available IR receiver modules (e.g., TSOP1738) could be used for efficient reception of the transmitted IR signals.

Author: EFY Lab - Copyright: EFY Magazine

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