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IR to 433MHz UHF Transceiver Mates With 10-Channel Remote Control Receiver Don’t have line-of-sight between your infrared remote and the 10-Channel Remote Control Receiver? Or do you simply want more range or want it to work outdoors? This IR To UHF Transceiver will solve the problem. D1 1N4004 +5V OUT IN GND 100 mF 16V 100W   REG1 78L05 K A 9–12V DC IN (50mA) Power supply: 9-12V DC, 50mA Infrared range: 10m line-of-sight UHF range: 30m in open space 100 mF 16V +5V 100 mF 16V E B A 47k 47k IRD1 IR RECEIVER C 100nF Q2 BC327 ANTENNA 1k TX1 l LED1 ACKNLG K Vcc 433MHz TX MODULE DATA 1.5k 1 ANT GND D 3 l Q1 2N7000 G S 433MHz Tx MODULE 2 ANT Vcc DATA GND IRD1 1 SC Ó2013 2 3 BC327 LED K A 2N7000 78L05 GND B E IR TO UHF TRANSCEIVER C D G S IN OUT 1N4004 A K Fig.5: the circuit of the IR To UHF Transceiver. IRD1 picks up the infrared signal and its output drives the Data input of TX1 (the 433MHz transmitter module) via FET Q1. Transistor Q2 drives the Acknowledge LED (LED1). T HE WAY IN which this device works is straightforward: it picks up the coded signal from your IR remote and converts it to a 433MHz UHF radio signal. This is then picked up by the 433MHz receiver in the 10-Channel Remote Control Receiver, which decodes the signal 66  Silicon Chip Specifications and switches its outputs accordingly. So, in effect, all it does is convert the remote’s infrared signals into a radio link. The result: longer range and no more line-of-sight problems. If you want to control the 10-channel receiver from another room or outdoors, this is the way to do it. The transceiver is quite compact and operates from a 9-12V DC supply. In operation, it must be located within range of the infrared remote so that its IR receiver can pick up the remote’s signals. An acknowledge LED on the front panel lights when a valid infrared signal is being received and retransmitted as a UHF signal. How it works Fig.5 shows the circuit details of the IR To UHF Transceiver. Its based on an infrared receiver (IRD1) and a 433MHz transmitter module (TX1) and not much else. IRD1’s pin 1 output is normally at 5V when no infrared signal is being received. This 5V “high” is inverted by Q1, an N-channel enhancementmode FET. It turns on when its Gate is high and so the Data input of the UHF transmitter is normally low (ie, at 0V). This low voltage keeps the UHF transmitter off. When an infrared signal is received from the remote, pin 1 of IRD1 pulses Q1 on and off. Each time FET Q1 turns off, a 1kΩ pull-up resistor at its drain pulls the Data input of TX1 to 5V and the UHF transmitter sends a signal. siliconchip.com.au Q2 100W 100nF 433MHz Tx MODULE DC IN BC327 LED1 A 100 mF GND DATA Vcc ANT. 47k REG1 1.5k CON1 100 mF 1k D1 4004 78L05 Q1 IRD1 100 mF 47k 2N7000 TX1 C 2013 15106132 evUHF i e c eR F HU ot r evi e c eR RI IR RECEIVERrto TRANSMITTER 23160151 Fig.6: install the parts on the PCB as shown on this layout diagram. LED1 must be mounted with 12mm lead lengths, while the infrared receiver (IRD1) goes in with 4mm lead lengths. The PCB clips neatly into the UB5 plastic case. Drill holes at each end for the DC socket and IRD1. At the same time, each time pin 1 of IRD1 goes low, transistor Q2 turns on and drives the Acknowledge LED (LED1) via a 1.5kΩ current-limiting resistor. So this LED flickers upon receipt of infrared transmission. Power for the circuit is derived from a 12V DC 100mA plugpack supply, with diode D1 providing reverse polarity protection. The nominal 11.4V supply at D1’s cathode is then fed to 3-terminal regulator REG1 which provides a 5V supply for IRD1 and TX1 (the 433MHz transmitter). go in next. It’s mounted on 4mm lead lengths so that its top is 10mm above the PCB. The PCB assembly can now be completed by installing the UHF transmitter (TX1). This module is mounted horizontally and so its four mounting pins will need to be bent down at right angles for insertion into its PCB pads. The antenna for this transmitter is a part of the track pattern on the PCB, so there’s no need to fit a separate antenna wire. Assembly The PCB simply clips into the integral ribs of the UB5 case. Before doing this, you have to drill a hole at each end to give access to the IR receiver and the DC socket. These holes are both 6mm in diameter and should be centred 7mm down from the top of the base (and centred horizontally). A 3mm hole must also be drilled in the box lid for the Acknowledge LED. The front panel label can be used as a template to determine the position of this hole. You can download this panel (in PDF format) from www. siliconchip.com.au (go to “Shop” and then “Panel artwork”). Once you have this file, print it out, attach it to the case lid and drill the LED hole to 3mm. A second copy of the artwork can then be printed onto photo paper and affixed to the lid using silicone or some other suitable adhesive. The hole for the LED can either be cut out or punched out with the back end of a 3mm drill bit. In use, the IR To UHF Transceiver should be placed no closer than 1m to the 10-Channel Remote Control The IR to UHF Transceiver is assembled on a PCB coded 15106132 and measuring 79 x 47mm. This is housed in a UB5 plastic utility box measuring 83 x 54 x 31mm. Fig.6 shows the parts layout on the PCB. Install the resistors and diode D1 first, taking care to ensure that the latter is correctly orientated. REG1, Q1 & Q2 can then be mounted but be careful not to get these mixed up. Once these parts are in, install the capacitors but watch the polarity of the 100µF electrolytics. In addition, the tops of the electrolytics must be no more than 15mm above the PCB (so that they will later clear the case lid). LED1 is mounted with the top of its lens 17mm above the PCB surface. That’s done by pushing it down on a 12mm cardboard spacer inserted between its leads before soldering it to the PCB. Make sure the LED is orientated correctly, with its anode (longer) lead going to the pad marked “A”. The infrared receiver (RX1) can siliconchip.com.au Final assembly Par t s Lis t 1 PCB, code 15106132, 79 x 47mm 1 front panel label, 78 x 49mm 1 433MHz transmitter (TX1), (Jaycar ZW-3100, Altronics Z 6900) 1 UB5 utility case, 83 x 54 x 31mm 1 PCB-mount DC socket Semiconductors 1 infrared receiver, TOSOP4136 or similar (RX1) 1 2N7000 N-channel enhance­ mentmode FET (Q1) 1 BC327 PNP transistor (Q2) 1 78L05 regulator (REG1) 1 1N4004 1A diode (D1) 1 3mm blue high-brightness LED (LED1) Capacitors 3 100µF 16V PC electrolytic 1 100nF MKT polyester Resistors (0.25W, 1%) 2 47kΩ 1 1kΩ 1 1.5kΩ 1 100Ω Receiver to prevent signal overload. In practice of course, the two are likely to be much further away than that and you should get reliable operation at distances up to 30 metres in open space. What’s coming Finally, we plan to publish a version of this IR To UHF Transceiver that fits inside an IR remote control. We also plan to publish a companion UHF To IR Receiver unit so that trhe two can be used as an IR range extender with any equipment. SC June 2013  67