Fullscreen HTML5Med Res (??MB)HTML4

Infrared Remote IR remote contro This simple device lets you operate your CD/DVD player, set-top box (even the newest ones!), VCR or other program source using its remote control from another room in the house. It receives the signal from the remote control and relays this to the other room via a 2-wire cable. An infrared LED then retransmits the signal to your remote controlled equipment. By John Clarke Yes! This one does work with the new Foxtel Digital set top boxes! 46  Silicon Chip siliconchip.com.au M odern consumer entertainment equipment invariably includes an infrared remote control. In fact, the equipment is often almost totally reliant on its operation via the infrared remote control, leaving itself relatively free of switches and controls. Operation via the remote controls is quite handy if you are in the same room as the equipment, however many homes now have a second TV set or set of loudspeakers that are located in another room. These are usually linked to the main equipment using wiring or via a wireless transmitter/ receiver. So how do you control the equipment from another room? The answer is to use a remote control extender as described here. In use, the Infrared Remote Extender sits somewhere visible (eg, near a TV set or amplifier) and receives signals from the remote control. The arrangement is shown in Fig.1. The Infrared Remote Extender converts these IR REMOTE EXTENDER EQUIPMENT TO BE CONTROLLED TV 10: 02: 30 IR RECEIVER IR LED X an X 1 1 X X HANDHELD IR REMOTE CONTROL 0 X 1 0 X SECOND ROOM MAIN ROOM Fig. 1: it’s a simple concept – instead of directly controlling equipment the infrared signal is detected and sent by wire to an infrared LED which then mimics the detected signal, beaming it into the remote equipment signals into electrical impulses and feeds them down a shielded cable. The end of this cable attaches to an infrared LED placed near the equipment in the other room. The Infrared Remote Extender duplicates the infrared signal produced by the handheld remote control so that the equipment is controlled exactly as if you were in the same room. The idea of infrared extenders is not new – we have published several in the past, our last one in July 1996. As can be expected there have been many changes in audio and video equipment since then. Not surprising- Extender for olled equipment Here’s the complete project: the long grey cable runs back to the room where the device to be controlled is situated. The controller is aimed at the blue box, while the infrared LED on the end of the cable mimics the handheld controller signal and thus switches the device in the other room. siliconchip.com.au October 2006  47 + BURSTS OF 36-40kHz MODULATED IR REMOTE CONTROL IR LED DECODED PULSE SIGNAL IR RECEIVER DECODED OUTPUT λ λ CARRIER RE-INSERTED CARRIER RE-INSERTION TO PROVIDE FOR RE-TRANSMISSION BY EXTENDER A B C D E Fig.2: this diagram helps explain how the infrared Remote Control Extender works, as detailed in the text. Basically, when a button is pressed in the remote control (A), a unique (to that button) modulated pulse train is generated and is transmitted as invisible pulses of infrared light (B), which is received and decoded into a pulse train by the IR receiver (C/D). The carrier is reinserted (E) and is sent off to the remote infrared LED, which mimics the signal at A into the device to be controlled. ly, some of the latest remote controls will not work with the 1996 infrared extender. The reason they do not work is because these later designs transmit data at a much faster rate than older remote controls. This increase in data rate has come about because equipment now has a huge number of functions, so a lot more data has to be sent by the remote control. The Foxtel digital receiver using the Pace 400 series decoders is one example of a system that transmits at the faster data rate. Fig.2 shows the way an infrared remote control sends its signals to the equipment under its control. The infrared LED is driven as in circuit (A) and this sends bursts of signal that is typically transmitted at 36kHz although some remote controls transmit bursts at 38kHz or 40kHz. The signal burst is called the carrier and the sequence of bursts (or code) determines the function that the infrared remote control is sending to the receiver. This is shown in (B). So one set of bursts might change the volume while another set of bursts may alter the channel. 100Ω 4 λ A IC2b 6 A 2 2 5 10 36–40kHz CARRIER VR1 5k 7 6 1N4004 2 A K 1N4148 2.2nF 8 + 9V DC IN * USE 330 Ω 1W FOR 12V INPUT 8 7 12 IC2d 11 2.2k B E C Q1 BC327 220Ω λ CON2 A 14 IC2c CARRIER OSCILLATOR K A C 9 1 680pF K 470Ω B IC3 7555 3 K 0.5W A 3 A 4 D2 1N4004 3 IC2a LED1 ACKNOWLEDGE BC327 SC K 8 150 Ω* 13 K 2006 6 2 TSOP4136 E 7 D1 1N4148 IC2: 74HC00 1 LEDS 100k 5 2 1 1000 µF 16V 100 µF 16V 3 1 +5.1V K ZD1 5.1V 1W 100 µF 16V IC1 VISHAY TSOP4136 60 µs DELAY The infrared receiver (C) picks up these infrared signals and decodes them (D). A burst of signal from the transmitter is decoded as a low going level while the absence of any signal will be decoded as a high level. If we use the same type of receiver (C) in our Infrared Remote Extender we can reintroduce the carrier frequency and retransmit the infrared signal using the drive circuit shown in (A). Infrared remote controls send this data according to a standard such as the Philips RC5 code. The RC5 code sends data with a 36kHz carrier and CON1 100 µF 16V OUTPUT TO IR LED 5.6k 4 3 IC4 7555 5 3.5mm PLUG 1 A λ + K ZD1 LED2 IR LED INFRARED REMOTE CONTROL EXTENDER Fig.3: the circuit is based on the infrared receiver/decoder (IC1), some gates and two low-cost timer ICs. 48  Silicon Chip siliconchip.com.au 1 at ground potential. Otherwise the output is at Vs potential when there is no carrier signal detected. The circuit Fig 4: inside the TSOP4136 Infrared Receiver IC. Its job is to detect the modulated pulse train from the handheld infrared remote control, reject any other noise and then present a decoded signal at its output. the signal bursts are 889ms long. There are other standards such as those by Sony and Sharp where the carrier is 40kHz and 38kHz respectively. A later standard and one used by the Foxtel digital receiver is the RC6 standard. This transmits bursts of the 36kHz signal in shorter bursts 444ms long. Our latest Infrared Remote Extender uses a Vishay TSOP4136 receiver that can decode all the current data rates used by infrared remote controls. Its block diagram is shown in Fig.4. The TSOP4136 comes in a small 3-lead package with an integral plastic lens on one side. The lens focuses the infrared light onto an internal receiver 0 00 $10 I Z E R P OL! PO diode. The signal from this diode is amplified and filtered to remove signals outside the 36kHz, 38kHz and 40kHz carrier frequencies. The filtering also removes interference from sources such as fluorescent lights when driven directly from the 240VAC mains or from compact fluorescent lights which operate above 100kHz. AGC (automatic gain control) is applied so that the demodulator receives adequate signal without overload. The demodulator converts the carrier modulation into an output signal that is then available at the output terminal. The presence of carrier signal sets pin Fig.3 shows our new Infrared Remote Extender circuit. The demodulated output from IC1 is fed to NAND gates IC2a & IC2b. IC2a drives the acknowledge LED (LED1) via a 470W resistor which should flash in response to the signal transmitted by your remote control. IC2b’s output is fed via diode D1 to pins 2 & 6 of IC3, a 7555 CMOS timer which is used here as a high speed comparator. This part of the circuit is there to correct a quirk of IC1, in that its output responds faster to the presence of IR signal (when its output goes low) than when signal ceases and the output goes high again. The difference is only around 60ms but it is critical in ensuring that the infrared remote control extender reproduces the original transmission as closely as possible. Normally in the absence of infrared signal, the output of IC1 is high and so the output of IC2b is low and diode D1 therefore holds the 680pF capacitor discharged. Pins 2 & 6 of IC3 are therefore 2006 SILICON CHIP Excellence in Education Technology Awards Closing in a few days! SILICON CHIP’S Excellence in Education Technology awards carry a prize pool of $10,000. Separate awards will be made to students of secondary schools throughout Australia and to students of universities and TAFE colleges throughout Australia. The secondary school awards have three categories: AWARD FOR EXCELLENCE (a) Best final year assignment of an individual student involving electronics technology. (b) An award to the school sponsoring the winning individual student. (c) Best school project involving electronics technology. The university and TAFE college awards have three categories: (a) Best project from a student as part completion of a degree, diploma or certificate in electronics or a related field (ie, mechatronics). (b) Best research project from a post-graduate student working in an area of applied electronics. (c) An award to the university faculty or school sponsoring the best research project. Entries and judging The awards will be judged by the editorial staff of SILICON CHIP, convened as a judges panel. The decisions of the judges will be final. Entry requirements are as follows: (1) A description of the project in no more than 1000 words. (2) Full circuit and wiring diagrams, performance plots, etc. (3) Good quality photographs to show all visual aspects of the project. (4) Details of software. Entries for the 2006 awards close on October 16th, 2006. All submissions will be confidential, until the winners are announced, in the December 2006 issue of SILICON CHIP. Each award will take the form of a cash prize and a commemorative plaque. All enquiries about these awards should be directed to the editor via email to: awards<at>siliconchip.com.au siliconchip.com.au October 2006  49 the same resistors connected to pin 3. When the capacitor voltage falls to 1/3 the supply voltage, the pin 3 output goes high and charges the capacitor again. The positive supply to IC4 is decoupled with a 1000mF capacitor. This filters out supply modulations at the oscillator frequency that could otherwise be detected by IC1 via the supply rail. The output from IC3 is inverted with NAND gate IC2c and applied to pin 12 of NAND gate IC2d. The carrier frequency is fed to pin 13 of IC2c. Thus IC2c gates the carrier on and off in response to the detected signal from IC1 and this will reconstitute the original IR signal from the remote control. IC2d drives transistor Q1 and in turn this drives the infrared LED (LED2) via a 220W resistor. Fig.5: this scope grab demonstrates the operation of the Remote Control Extender. The top trace (yellow) is the detected signal at pin 3 of IC2a which drives the acknowledge LED. The centre trace (blue) is the 38kHz carrier signal from pin 3 of IC4. The bottom trace (magenta) is the gated 38kHz carrier at the collector of transistor Q1. D1 100 µF 4148 680pF 100Ω CON1 D2 ZD1 16001120 220Ω IC4 7555 5.6k 2.2k 100 µF 100k IR CONTROL CODES FROM REMOTE Q1 BC327 IC3 7555 IC1 The Infrared Remote Extender is built onto a PC board coded 02110061 and measuring 79 x 47mm. It is housed RED N1000 ETXE EµTFO MER DERARF NI 2.2nF LED1 VR1 5k IC2 74HC00 ACKNOWLEDGE LED 470Ω low and pin 3 of IC3 is high. When IC1 receives an infrared signal, pin 6 of IC2b goes high, diode D1 is reverse biased and so the 680pF capacitor begins to charge towards the 5.1V supply via the 100kW pull-up resistor. After 60ms the voltage reaches 2/3 the supply and pin 3 of IC3 goes low. So this adds a delay of 60ms. When IC1 ceases receiving an infrared signal from the remote control, its pin 1 goes high, taking pin 6 of IC2b low. The 680pF capacitor is quickly discharged via diode D1, allowing pin 3 of IC3 to go high almost instantly. Thus we have a delay for negativegoing signals from IC1 but negligible delay for positive going signals (this is because IC2b inverts). Construction 100 µF CON2 OUTPUT TO IR LED 9V DC FROM PLUG PACK 150Ω Fig. 6: here’s the component overlay for the Infrared Remote Extender, with a matching photograph below. Watch those polarised components! Reinsertion of carrier IC4 generates the carrier signal that was originally present in the IR signal from the remote control. It is another 7555 CMOS timer but this time connected to oscillate at between 36kHz and 40kHz, depending on the setting of trimpot VR1. Its operation is as follows: the 2.2nF capacitor charges up via VR1 and the series connected 5.6kW resistor when the pin 3 output of IC4 is high. When the capacitor voltage reaches 2/3 the supply voltage, the pin 3 output goes low and the capacitor is discharged by 50  Silicon Chip siliconchip.com.au Parts List – Remote Control Extender And here’s how it fits into the UB5 box. You will need to drill holes in both ends for the IR receiver/decoder (at right in the above photo) and the power and IR LED socket. Both of these are shown in more detail below. in a small plastic case measuring 83 x 54 x 31mm. Begin construction by checking the PC board for any defects such as shorted tracks or breaks in the copper and for correct hole sizes. Holes for the DC socket and 3.5mm jack socket will need to be larger than the 0.9mm holes required for the other components. Insert the links and resistors first taking care to place each resistor in its correct place. Note that if you are planning to use a 12V plugpack instead of the recommended 9V plugpack, then the 150W resistor will need to be 330W 1W instead. Use the resistor colour code table as a guide to finding each value. You can also use a digital multimeter to check each resistor before inserting into the PC board. Solder each lead and cut the leads short against the underside of the PC board. Now install the diodes, transistor and ICs, taking care to orient them with the correct polarity. IC1 is mounted so the top of the package is 13mm above the top surface of the PC Resistor Colour Codes 1 1 1 1 1 1 1 No 1 1 1 1 1 1 1 Value 100kW 5.6kW 2.2kW 470W 220W 150W 100W 4-Band Code (1%) brown black yellow brown green blue red brown red red red brown yellow violet brown brown red red brown brown brown green brown brown brown black brown brown siliconchip.com.au 5-Band Code (1%) brown black black orange brown greeen blue black brown brown red red black brown brown yellow violet black black brown red red black black brown brown green black black brown brown black black black brown 1 PC board, code 02110061, 79 x 47mm 1 UB5 translucent clear or blue box, 83 x 54 x 31mm 1 9VDC 150mA plugpack 1 stereo 3.5mm PC-mount jack socket 1 PC-mount DC socket 1 mono 3.5mm jack plug 1 5m length of single core shielded cable 1 20mm length of 5mm heatshrink tubing 1 150mm length of 0.7mm tinned copper wire Semiconductors 1 TSOP4136 infrared receiver/ decoder (Vishay) (IC1) 1 74HC00 quad NAND gate (IC2) 2 7555 CMOS timers (IC3,IC4) 1 BC327 PNP transistor (Q1) 1 5.1V 1W zener diode (ZD1) 1 1N4148 diode (D1) 1 1N4004 1A diode (D2) 1 3mm red high-intensity LED (LED1) 1 5mm infrared LED (LED2) Capacitors 1 1000mF 16V PC electrolytic 2 100mF 16V PC electrolytic 1 2.2nF MKT polyester 1 680pF ceramic Resistors (0.25W 1%) 1 100kW 1 5.6kW 1 2.2kW 1 470W 1 220W 1 100W 1 150W 1/2W 1 5kW horizontal trimpot (VR1) (code 502) board. The capacitors can go in next. Note that the electrolytic types must be oriented with the polarity shown and the 1000mF capacitor adjacent to IC4 must lie on its side as shown in the photograph to allow room to fit into the box. LED1 is mounted with about a 10mm lead length above the PC board surface to allow it to be bent over at 90° and insert into a hole in the side of the box. Take care to orient it with the anode (longer lead) towards the Capacitor Codes mF Code 2.2nF .0022mF 680pF NA Value IEC Code 222 681 EIA Code 2n2 680p October 2006  51 Transmitting audio and video between rooms It is now common for households to have a second TV set that is located in another room. They can be used as a standalone set that receives signal from a TV antenna in the normal way. However, you may wish to connect the set to your main system in order to play DVDs or watch something from a cable or satellite receiver or from digital set-top boxes. The signal from these sources can be in either high definition or standard definition format. A simple way of connecting these to the second set is to use a video balun with audio. In this way, the composite video signal and the left and right audio signals are converted to a balanced line using a balun style transformer. The signal is carried via Cat-5E cable using RJ45 connectors. At the receiving end, a second video balun with audio converter returns the signal to its original form. These units are passive and require no power connection. A video balun with audio is available from Jaycar (Cat QC-3424) (www.jaycar.com.au). You will need two units to send and receive. As an alternative, you could use a 2.4GHz stereo AV transceiver. This avoids having to run wiring for the audio-visual connections. Altronics (www.altronics.com.au) sell their S-8771 transmitter and S 8792 receiver for this application. (Note that a plugpack and adaptor are required for each unit, M 9236 and M 9187 respectively). Similarly Jaycar sell an AR-1842 transmitter/receiver for this application. Both Jaycar and Altronics also supply versions of 3.5mm MONO PLUG PLUG COVER SINGLE CORE SHIELDED CABLE these audio video transceivers that include infrared remote control extenders at a higher price. If you want to send the video signal in a higher quality form such as S-video or component video or as a VGA signal, then video baluns are available for these that transmit using Cat-5E cabling. The Jaycar QC-3423 is used for S-video and the QC3429 is for component video. Note that you require two units (of the same type) in order to send and receive via Cat-5E cable. These units do not provide for audio transmission. Sending audio can be as simple as running speaker wires from the main amplifier to a second set of loudspeakers. Alternatively you can send audio using just the audio section of the ‘video balun with audio’ unit from Jaycar (Cat QC-3424). A second unit is required to receive the audio. A stereo amplifier will be required to drive loudspeakers. For high definition, you can use the VGA baluns (QC-3428 available as a pair) to send resolutions ranging from 640 x 480 through to 1280 x 1024 pixels. We tested this VGA balun for use with a computer that sent 1024 x 768 pixel video signals over 60m via the Cat-5E cable to an LCD projector. This system was installed in a church for video presentations. One problem was that the common ground connection on the receiving VGA balun unit had to be earthed (to mains earth) in order for it to work. When testing in the home the earthing needed to be at the sending end rather than the receiving end balun unit. You may not need to earth the balun in your application. LED2 AND CONNECTIONS COVERED IN HEATSHRINK SLEEVING A K SHIELD BRAID CONNECTED TO PLUG SLEEVE SHIELD BRAID CONNECTED TO CATHODE (K) OF LED2 Fig.7 (above): here’s how to make up the lead for the IR LED. A close-up of the LED, encased in heatshrink, is shown at right. edge of the PC board. Finally, install the trimpot, the DC socket and the 3.5mm jack socket. Installation The PC board is installed into the small translucent plastic case. Before you can insert the PC board into the box, drill out the hole for the 3.5mm jack socket. This needs to be 10mm down from the top edge of the box and 20mm in from the edge of the box. The advantage of the clear box is that the positions for the DC socket and IC1 lens hole can be readily seen when the PC board is clipped into the box. Mark and drill out these holes and the LED hole. The acknowledge LED is bent over at 90° to insert into the hole. We used the box upside down with 52  Silicon Chip red remote control is sending a signal to the Infrared Remote Extender. You can verify that the infrared LED retransmits the signal to your equipment by using the extender in another room with LED2 located near to the equipment to be controlled. VR1 may require some adjustment so that the extender works SC the equipment correctly. the lid used as the base. The screw covers on the box act as rubber feet for the box. If you are using a different box, then use some stick-on feet on the base of the box. The IR LED lead is made up as shown in Fig.7. The single core shielded cable is connected to the DC plug at one end and the IR LED at the other. The LED is insulated on at least one of the leads with some insulation tape or heat shrink tubing and also it is covered in heat shrink tubing but leaving the lens end exposed. Testing Connect power using the plugpack and check that the voltage across ZD1 is about 5.1V. If so, check that the acknowledge LED flashes when an infra- Fig 8: the same-size PC board pattern. siliconchip.com.au