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Driveway Monitor Pt.2: By JOHN CLARKE Last month, we introduced our new Driveway Monitor and described how it worked. This month, we describe how to build, test and install it in your driveway. We also describe the various options so that you can build it to operate just the way you want. B UILDING the Driveway Monitor is straightforward, with all parts mounted on two PCBs – a detector PCB coded 15105151 (104 x 78mm) and a receiver PCB coded 15105152 (79 x 47mm). As explained last month, the receiver PCB can be built in two versions. One version uses LEDs and a piezo buzzer to warn of vehicle arrival and exit, while the alternative version uses relays which are wired across the buttons of an external remote control PCB. This is then used to activate a remote-controlled mains switch. Of course, there’s nothing to stop you from building both versions of the receiver PCB if you want both sets of functions. As long as they’re paired to the detector unit, they will 66  Silicon Chip both be triggered whenever a vehicle is detected in the driveway. Detector assembly Construction can start with the detector PCB assembly – see Fig.12. Begin by installing the HMC1021 magneto-resistive sensor (Sensor1) at centre-left. This is a surface mount device (SMD) and is soldered to matching pads on the top of the PCB. To install it, first centre it on its pads making sure it is correctly orientated, then tack solder one of the corner pins. That done, check the alignment, adjust it if necessary and solder the remaining pins. The first pin can then be refreshed with some extra solder. Don’t worry if you get any solder bridges between the pins when soldering the device in. They can easily be removed afterwards using no-clean flux paste and solderwick. Check the connections under a magnifying glass to ensure that all the pins have been correctly soldered. Once Sensor1 is in place, the resistors can be installed. Table 1 shows the resistor colour codes but you should also check each one using a digital multimeter before soldering it in place. Be sure to fit the correct value at each location. Resistor R1 (top left) is normally shorted out by a track on the underside of the PCB. As stated last month, this resistor is omitted if you will be charging the NiMH cell from a solar siliconchip.com.au siliconchip.com.au + CON1 47 µH K LM2936Z-5.0 VR3 10k DETECT LK2 LK3 TP1 ENTRY EXIT SWAP AA CELL TX1 GND DATA Vcc ANT. ANTENNA = 168mm PIC16F88 IC2 Q1 IRF540 Q2 IRF9540 REG2 ID LK1 A + SINGLE AA CELL HOLDER 100k 5.5VSET VR2 1M 10 µF Sensitivity 4004 330Ω 100nF 1nF 10k Vout 22k 10Ω 10k 10Ω 220Ω BC327 2.2k LED1 470 µF 10V 4.7k BC327 + Low ESR 100nF Q3 500Ω 2.2k 1nF 1 µF Q4 1 µF 100nF IC1 AD623 B2 VR1 100nF Low ESR 470 µF 10V Ferrite 1 µF D2 IC3 + 4004 100nF 1 5 1 5*0SEE 1 5 1 TEXT 15105151 1nF C 2015 SENSOR1 B1 HMC1021 HMC1021 + 220 µF 10V D1 1 µF R1* TP5.5V Low ESR LMC6041 TO SOLAR – CELL REG1 TL499A L1 + DRIVEWAY SENTRY ALERT panel. Alternatively, you will have to cut the track and fit this resistor if you intend using a 12V or 9V DC plugpack to charge the cell instead of using a solar panel. A 220Ω 1W resistor should be fitted for a 12V DC plugpack, while a 100Ω 1W resistor is used for a 9V DC plugpack. Don’t forget to cut the PCB track underneath the resistor – a section of the track has been thinned so that it is easy to break. The next step is to fit the two links and their ferrite beads to the right of Sensor1. It’s basically just a matter of inserting a length of tinned copper wire through each bead, then bending the leads down on either side so that they go through the holes in the PCB. Follow with the two 1N4004 diodes (D1 & D2), taking care to ensure they go in with the correct polarity. An IC socket should then be fitted for PIC microcontroller IC2, after which you can solder IC1, IC3 and REG1 directly to the PCB (or you can install them in IC sockets). Be careful not to get these three 8-pin devices mixed up. The seven PC stakes can now be installed on the board. Five of these are located at the TP 5.5V, TP GND, TP1, Vout (next to IC2) and ANT (for the UHF antenna) positions, while the other two are fitted between coil L1 & REG1 to terminate L1’s leads. Now for the capacitors. Fit the ceramic and MKT polyester types first, then install the five electrolytics. Note that the 470µF and 220µF values must be low-ESR types. Make sure that all the electros are correctly orientated. Mosfets Q1 & Q2 are next on the list, along with transistors Q3 & Q4 and regulator REG2. Be careful not to get the Mosfets mixed up – Q1 is an IRF540 N-channel type, while Q2 is an IRF9540 P-channel device. There are three trimpots on the PCB and these can now be installed. VR1 is a 500Ω trimpot and may be marked as “501”, while VR2 & VR3 are both 10kΩ trimpots and may be marked as “103”. Be sure to push them all the way down onto the PCB before soldering their leads. LED1 can then be soldered in place with its anode lead (the longer of the two) going to its “A” PCB pad. Follow with the 3-way DIL header. This part is installed to the right of IC2, with the shorter length pins going into the PCB. CON1, the 2-way screw TP GND Fig.12: install the parts on the detector PCB as shown here, starting with the HMC1021 magneto-resistive sensor. Note that resistor R1 is omitted if you are charging the AA cell from a solar panel (see text). The detector unit’s antenna consists of a 168mm length of insulated hook-up wire. This should be fitted with a short length of heatshrink tubing at its far end so that it cannot short against any parts on the PCB. terminal block, can then go in with its wire entry holes towards the left. Winding the inductor Inductor L1 is wound on a powdered-iron toroid core using 32 turns of 0.5mm enamelled copper wire. Wind the turns on neatly in a single layer around the core (see photo), then trim and strip the wire ends of the enamel insulation. The leads are then soldered to the coil’s PC stakes, after which the August 2015  67 Table 1: Resistor Colour Codes o o o o o o o o o o o No.   1   1   2   1   2   1   1   1   1   2 Value 100kΩ 22kΩ 10kΩ 4.7kΩ 2.2kΩ 1kΩ 330Ω 220Ω 100Ω 10Ω toroid is secured in place using two cable ties that loop through through adjacent holes in the PCB. The detector PCB assembly can now by completed by installing the cell holder, the UHF transmitter module and the antenna. The battery holder must be orientated as shown and is secured to the PCB using two selftapping screws. Its leads are then cut short and soldered to their PCB pads at either end of the holder, with the red wire going to the “+” pad and the black wire to the 0V pad. Take care with the orientation of 4-Band Code (1%) brown black yellow brown red red orange brown brown black orange brown yellow violet red brown red red red brown brown black red brown orange orange brown brown red red brown brown brown black brown brown brown black black brown the UHF transmitter module. Its pin designations are marked along one edge and it’s just a matter of fitting it to the PCB with its antenna pin towards the bottom edge of the PCB (ie, towards the negative end of the cell holder). The antenna consists of a 168mm length of insulated hook-up wire. Solder it to the antenna (ANT.) PC stake, then cover the connection with a short length of 1mm-diameter heatshrink tubing to prevent the lead from breaking at the solder joint. Fitting it in a case The completed detector PCB can now be fitted inside a standard IP65 polycarbonate case measuring 115 x 90 x 55mm. This requires no preparation apart from drilling a 12.5mmdiameter hole in one end to accept a 3-6.5mm cable gland to feed through the wiring from the solar panel (or from a plugpack). This hole is positioned 25mm up from the outside base of the case and is centred horizontally. Use a small pilot drill initially, then carefully enlarge the hole to size using larger drills and a tapered reamer until the gland fits. That done, the PCB assembly can be lowered into the case and secured using four M3 screws that go into the threaded corner bushes. The Neoprene Left: inside the solar garden light. Its AAA cell and white LED must be removed and the cable from the detector unit soldered across the battery holder contacts. 68  Silicon Chip 5-Band Code (1%) brown black black orange brown red red black red brown brown black black red brown yellow violet black brown brown red red black brown brown brown black black brown brown orange orange black black brown red red black black brown brown black black black brown brown black black gold brown Table 2: Capacitor Codes Value 1µF 100nF 1nF µF Value IEC Code EIA Code 1µF   1u0 105 0.1µF 100n 104 0.001µF    1n 102 seal for the lid then needs to be placed inside the surround channel and cut to size. Note that the join in this seal must be along the lower, longer edge of the lid (the detector unit is later installed with the longer edges of the box running horizontally, so that the PCB sits vertically to ensure maximum sensor sensitivity). If you only require a UHF transmission range of 40m or less, then the antenna wire can be positioned inside the case (see photo). Make sure that the the end of the antenna cannot short against the PCB or any of the parts (fit some heatshrink tubing over the end to insulate it). Alternatively, for longer transmission ranges of up to 200m, the antenna wire can be fed out through a small hole in the bottom edge of the box and this hole sealed with silicone to keep water out. Solar panel A free-standing solar panel garden light will typically cost $2-3, with better quality units coming in at around $5. This will include the required solar panel, a single NiMH cell and (typically) a white 5mm LED. However, the NiMH cell is usually a AAA type and so won’t be usable. Even if a AA cell is fitted, it will invariably be a low-cost (read low-quality) unit and you will be better off discarding it and buying a new one. siliconchip.com.au One problem is that the step-up voltage regulator on the detector board will not initially operate if the NiMH AA cell is discharged. That means that the cell must be charged before testing the unit. If you don’t have a suitable NiMH charger, then the solar panel can be used to charge the cell. It’s simply a matter of removing the AAA cell and the white LED from the garden light, then running leads from the solar panel to the detector PCB and installing the AA cell in its holder. Note that the solar cell must be in sunlight in order for charging to take place. Alternatively, you can temporarily run the leads from the solar cell to an external cell holder. The detector PCB can then be temporarily fitted with an alkaline AA cell for testing. Detector PCB set-up Having installed the detector PCB in its case, it’s time to make a few adjustments. Just follow this step-bystep procedure: (1) Adjust trimpot VR1 to mid-setting and set VR2 & VR3 fully anticlockwise. (2) Install IC2 in its socket, making sure that it’s correctly orientated. Fit the other ICs and REG1 if you’ve installed sockets for these as well. (3) Fit the AA cell to its holder, then measure the voltage between the TP5.5V and GND PC stakes and adjust VR2 for a reading of 5.5V. If you cannot get sufficient voltage, it may be due to the AA cell. Check the cell voltage and if that’s OK, try momentarily removing the cell and reinserting it so that REG1 starts properly. (4) Check that there is +5V at pin 14 of IC2 (this could be from 4.85-5.15V, depending on the particular regulator used for REG2). (5) If all is OK, the unit should now be ready to detect magnetic field variations (about 10s after the cell is installed). Orientate the unit so that the PCB is vertical and check that the bicolour LED lights red or green if the unit is rotated by a few degrees. The LED should then go out again after a brief period if the unit is kept stationary. (6) Check that the unit can detect a pair of steel pliers if they are passed close to the sensor. LED1 should light red if the pliers are passed in one direction and green in the other. Note that, in practice, IC1’s output siliconchip.com.au The detector PCB is secured to integral threaded corner posts inside its IP65 case. Be sure to install the NiMH cell the right way around and note that the cell must be charged before testing the unit. Our prototype had the cable gland fitted to a side panel but fitting it to the bottom panel would be preferable in many installations. should not swing too close to the supply rails. Output swings close to 0V (<0.3125V) or close to 5V (>4.6875V) will be indicated by the bicolour LED alternately flashing red and green at a 1s rate. If that happens, there is either a high magnetic field in the vicinity of the sensor (eg, a magnet) or IC1’s gain is set too high by VR1. Diagnostic mode Now install a jumper between LK2 & LK3 as shown on Fig.13. This sets August 2015  69 you want to trigger a remote-controlled mains switch for a set period of time only when a vehicle arrives. In that case, you would install a jumper on LK1 to signal vehicle entry but no jumper link for LK2 (exit). If you want to trigger the remote for both directions, install both LK1 & LK2. LK3 is installed if the arrival and departure indications are incorrect (it simply swaps them around), while installing a jumper between LK1 & LK2 sends a non-directional indication to the receiver. Note that the link settings operate in exactly the same way for both receiver versions. Detector unit installation The detector unit must be attached to a non-metallic post or wall adjacent to the driveway. You can either mount the solar panel on top of the detector or leave it in the garden light housing as shown at right. Make sure that the solar panel is mounted in a sunny location. the unit into diagnostic mode which is used for testing only, since other circuit functions are disabled and the circuit draws a relatively high current while it’s in place. By installing this link, variations in IC1’s output can be monitored using a multimeter connected between Vout PIC16F88 JUMPER SHUNTS MAKE SELECTION WHEN IN PLACE LK2 LK3 ENTRY TRANSMITTED TO RECEIVER EXIT TRANSMITTED TO RECEIVER SWAP ENTRY & EXIT DETECTION SENSE JUMPER SHUNT FOR NON–DIRECTIONAL SENSING PIC16F88 IC2 LK1 IC2 LK1 LK2 LK3 and TP GND. You can either rotate the detector unit or swipe a pair of steel pliers close to the sensor and then check that the DMM shows the resulting variations in IC1’s output. Note: this mode is not used when adjusting IC1’s gain. That’s done later by trial and error when the detector unit is installed in the driveway. Setting the identity The diagnostic mode is also used when adjusting identity trimpot VR3. If you have only one detector unit, simply set VR3 fully anticlockwise for a UHF transmission identity of “1”. If you have more than one detector unit, they will each need a different identity to avoid interference. It’s just a matter of installing the diagnostic link and adjusting VR3 so that the voltage at TP1 matches an identity setting voltage as shown in Table 3. PIC16F88 Linking options IC2 LK1 LK2 LK3 JUMPER SHUNT FOR DIAGNOSTIC TESTING Fig.13: this diagram shows the linking options for the detector PCB. The diagnostic jumper between LK2 & LK3 is for test purposes only. 70  Silicon Chip As mentioned last month, jumpers LK1-LK3 determine the information that’s encoded into the UHF transmission sent to the receiver – see Fig.13. As shown, LK1 is installed for arrival (entry) notifications, while LK2 gives departure (exit) notifications. Depending on your requirements, you can either install both these links or leave one or the other out. For example, let’s say that you build the relay version of the receiver and The detector unit can be installed alongside the driveway on a post or wall. Before mounting it though, you should check that the unit will reliably detect a passing vehicle. That can be done by temporarily placing the unit on a wooden box or stool so that it’s about 60-80cm above ground (ie, so that it lines up with the metal body of a car). If you like, you can leave the diagnostics jumper in place so that you can check that Vout varies as a vehicle passes by. If it does, remove the diagnostics jumper and check that the detector unit lights the green LED for one direction of the vehicle and the red LED for the other direction. If the vehicle isn’t reliably detected, adjust sensitivity trimpot VR1 clockwise to increase IC1’s gain (but don’t set VR1 fully clockwise). Conversely, wind VR1 anti-clockwise to decrease the gain if the red and green LEDs in the bicolour LED flash alternately at a 1s rate. In practice, VR1 should be set somewhere between fully anticlockwise and about three-quarters clockwise in order to achieve reliable detection. During this test procedure, the detector must be kept still, otherwise it will detect changes in the Earth’s magnetic field due to its own movement. If that happens, the tracking thresholds then need to readjust so that they sit equally above and below the amplified sensor voltage and this could take some time (eg, over a minute). If you want the tracking thresholds to readjust faster, you can remove the AA cell for a few seconds and then reinstall it. By doing this, the thresholds will readjust within 10s. Another way siliconchip.com.au CON1 100 µF EXIT A PIEZO TRANSDUCER ID 2x10k DRIVEWAY SENTRY ALERT MONITOR ENTRY LED2 DATA RX1 GND GND GND LED1 A TP2 VR2 (DUR.) TP1 VR1 ANT DATA DRIVEWAY SENTRY ALERT MONITOR ANT. GND Vcc GND GND RX1 100Ω Vcc TP2 VR2 (DUR.) 100Ω Vcc OFF 15105152 Rev.B 2 5C1 52015 0151 DATA 1k 4148 ON 1k PIEZO 12V DC IN D2 PIC12F675 RELAY2 DATA ID REG1 100nF TP GND Vcc RELAY1 ANTENNA = 168mm 78L05 100 µF 4004 100 µF D1 D3 2x10k VR1 ANT TP1 15105152 Rev.B 2 5C1 52015 0151 100Ω 4148 IC1 1k CON1 PIC12F675 REG1 100nF TP GND +12V 0V 12V DC IN ANT. VERSION 2 ANTENNA = 168mm 78L05 100 µF 4004 D3 IC1 VERSION 1 Fig.14: the PCB parts layouts for the two receiver versions. Build Version 1 if you want to activate the buttons on a separate remote control PCB (eg, to control a UHF remote mains socket). Alternatively, build Version 2 if you only require an audio/visual warning when a vehicle passes the driveway detector unit. These views show the two fully-assembled receiver versions. Make sure that all polarised parts are correctly orientated and fit heatshrink over the lead connections to the PC stakes to prevent the wires from breaking at the solder joints. is to change LK3 (ie, either install the jumper or remove it). Each time LK3 is changed, the detection thresholds re-track within 10s. Once it’s working, the detector unit can be permanently mounted using the holes provided in the box corners (these holes are accessible when the box lid is removed). These holes could either be used to directly secure the unit or you could use them first to attach a bracket (preferably made from non-magnetic material) which is then attached to a wall or post. Connecting the solar panel The solar panel is connected to the detector via a length of figure-8 cable. This cable is passed through the cable gland, either in the side or bottom edge of the case, and terminated in screw terminal block CON1. Be sure to connect the cable with the correct polarity (the red wire that’s connected to the solar panel is positive). siliconchip.com.au Be sure also to disconnect the solar panel from the LED inside the garden light fixture. The fixture should then be installed nearby in a sunny part of the garden, to ensure that the solar panel gets full sun during the day. If that arrangement isn’t convenient (eg, you don’t have a nearby garden bed), then the solar panel can be removed from the light fixture and mounted separately. It may even be possible to mount it on top of the detector unit using a suitable non-metallic bracket, as shown in the photos. Finally, use neutral-cure silicone to seal the wire entry into the cable gland to keep moisture out of the case. The same goes for any other possible waterentry locations (eg, screw mounting holes for brackets etc). Receiver assembly Fig.14 shows the assembly details for the two receiver versions. Version 1 has the reed relays to trigger a remote control PCB, while Version 2 has the piezo buzzer and LED indicators for audio/visual warnings only. As previously mentioned, if you want both sets of functions, you will have to build both versions and set them to the same identity as the receiver. Note that the LEDs and piezo buzzer must be omitted if you build the relay version (Version 1), while the relays and diodes D1 & D2 are omitted from Version 2. In most cases, it’s just a matter of selecting which version you want to build and assembling the board to match its layout. Install the resistors first, then install diode D3 (1N4004). D1 & D2 (1N4148) should then be fitted if you are building Version 1. Note that D2 must be installed about 3mm proud of the PCB, since it needs to be later pushed to one side to make room for a polarised 2-way header. The PC stakes are next on the list and these are installed at TP GND, TP1, August 2015  71 lenses are 16mm above the PCB. That’s easily done by pushing each LED down onto an 11mm-high cardboard spacer that’s slid between its leads before soldering it in place. Off Contacts On Contacts Piezo transducer mounting The piezo transducer used in Version 2 mounts on two M3 x 9mm tapped spacers. These spacers are secured to the PCB using M3 x 6mm screws. The piezo transducer is then secured in place, again using M3 x 6mm screws. You will have to drill out the transducer’s mounting tab holes to 3mm diameter to accept the M3 screws. Once the transducer is in place, trim its wires to about 25mm, slip some 15mm lengths of 1mm-diameter heatshrink tubing over the wires and solder them to the adjacent PC stakes. The heatshrink can then be slid over the soldered connections and shrunk down to prevent the wires from breaking. UHF receiver Fig.15: this photo shows the wiring connections between Version 1 of the receiver PCB and the remote used for the Jaycar UHF mains socket. You will need to scrape away the solder masking from some of the pads on the remote PCB before soldering the leads. A UB3 plastic case is used to house Version 1 of the receiver PCB and its companion remote PCB. The front-panel label is optional. TP2 and the antenna (ANT.) terminal. If you are building Version 2, two extra PC stakes can be fitted to terminate the piezo buzzer leads (or you can elect to solder these leads directly to the PCB). The capacitors can be installed next. Note that for Version 2, the electrolytic capacitors must be no more than 14mm high so that they don’t foul the lid of the case. An 8-pin socket should now be fitted for IC1. Make sure that the socket sits flush against the PCB before soldering its pins, then install REG1 (78L05). The two relays can then be fitted if you are 72  Silicon Chip building Version 1. Check that these are orientated correctly (ie, notched ends aligned as shown on Fig.14). Version 1 also requires three polarised pin headers. Install these now, bending diode D2’s leads to the right as shown in one of the photos to clear the header that’s fitted between the two relays. Follow with the DC socket and trimpots VR1 & VR2. The two LEDs can then be installed for Version 2 (red for LED1 and green for LED2). These two LEDs must be installed with 11mm lead lengths, so that the tops of their You can now complete the PCB assembly by installing the UHF receiver module and the antenna. It must be orientated with its antenna pin to the left (ie, towards the DC socket). As with the transmitter, the pin designations are printed on the module. Once its in place, solder a 168mmlong insulated wire to the antenna PC stake. The soldered connection should then be covered with heatshrink tubing to prevent the wire from breaking. Version 1 final assembly The Version 1 PCB receiver assembly is housed in a UB3 plastic case (130 x 68 x 44mm) along with the PCB from the mains socket’s remote. We’ll describe how the two are wired together shortly, after the PCBs have been mounted in position. The receiver PCB mounts in the base of the case on M3 x 6mm tapped spacers. That’s done by first placing the PCB inside the case with the DC socket flush against one end, then marking out the four corner mounting holes. These holes are then drilled to 3mm and countersunk on the outside of the box using an oversize drill. A 9mm hole must also be drilled in the end of the case to provide access to the DC socket. This hole is positioned 17mm up from the base of the case and centred horizontally. You will also have to drill a small hole in this end of the case for the antenna lead if you siliconchip.com.au 0V Unit Pairing +12V Off Contacts On Contacts Fig.16: here’s how to make the connections to the Altronics UHF remote PCB. The red and black leads shown are all part of the original wiring. require a range greater than about 40m. Once that’s been done, the spacers and the receiver PCB can be secured in position using M3 x 10mm countersink screws and nuts. The antenna lead can be either run around the inside perimeter of the case or fed out through its exit hole. As with the detector unit, make sure that the end of the antenna cannot short against the PCB or any of the parts. The next step is to mount the remote control PCB. Suitable remotecontrolled mains sockets include the Jaycar MS-6142 and MS-6145 units and the Altronics A0340. Before removing the remote’s PCB module, the remote control mains socket should be set to operate as described in the instructions. This will familiarise you with the way the unit works and allow you to set the channel number and test its operation. Once you’ve done that, the handheld remote can be disassembled. The Jaycar remote has one screw located beneath the battery cover and when this is removed, the two halves of the remote case can be cracked open along the sides with a screwdriver. Similarly, the Altronics remote has two screws under the battery compartment lid and removing these allows you to split the case. It’s then just a matter of removing the remote PCB and connecting leads from the polarised headers on the receiver PCB. The 12V header is wired to the remote’s supply rails, while the other two headers are connected to the remote’s on and off button contacts for the selected channel. That way, when the Driveway Monitor is triggered, one reed switch closes briefly to turn the remote-controlled mains switch on. The other then closes briefly a few minsiliconchip.com.au utes later to turn the mains switch off. The leads from the headers can be run using 120mm lengths of light-duty hook-up wire. At the header end, it’s just a matter of crimping the wires into the crimp lugs and then lightly soldering them before pushing them into the header shell until they are captured by the tag springs. Use red & black leads for the 12V header and make sure you get the polarity correct. Figs.15 & 16 respectively show the connections to the Jaycar and Altronics remote PCBs. On the Jaycar unit, it will be necessary to scrape away the solder masking from the PCB before soldering the connections. Once all the wires are in place, fit cable ties around the switch wires to prevent them from pulling away from the PCB. It’s also a good idea to use neutral-cure silicone or hot-melt glue to hold the wires in place. In the case of a doorbell remote, it’s simply a matter of wiring the first reed switch across the switch contacts. This reed switch could also be used to trigger a burglar alarm. The remote PCB is mounted on the underside of the case lid. Both remotes have two holes that can be used as mounting points, although the Jaycar unit’s holes will need to A feature of the Driveway Monitor is “pairing”, whereby each detector and receiver pair are given a unique identity. This allows up to eight different pairs to operate in the same vicinity, which means that you can have multiple Driveway Monitors installed on your property. Pairing is set by adjusting trimpots VR3 in the detector unit and VR1 in the receiver to give matching voltage readings at their respective test points – see text & Table 3. be enlarged to 3mm. In each case, the unit is mounted on M3 x 9mm tapped spacers and secured using M3 x 6mm machine screws. We used countersink-head screws for the lid so that the heads sit flush with the panel to allow a front-panel label to be attached. Position the mounting holes so that the remote PCB is centred on the lid, then mount the PCB in position and plug the various leads into their corresponding sockets on the receiver PCB. Version 2 final assembly The Version 2 receiver is housed in a UB5 case (83 x 54 x 31mm), making it more compact than the Version 1 unit. In addition, no mounting hardware is required for Version 2 since the PCB simply clips into slots in the integral side channels in the case. Before installing the PCB, you will have to drill a 9mm hole for the DC socket. This should be positioned 20mm up from the base and centred horizontally. As with Version 1, drill a small hole for the antenna lead if you require a range greater than about 40m (ie, up to 200m). You can then clip the receiver PCB into position and either feed the antenna wire through its hole or run it around inside the case. Finally, three holes have to drilled in the lid – two for the indicator LEDs Table 3: Identity Voltage Settings Identity Minimum Setting Maximum Setting Recommended 1 2 3 4 5 6 7 8 0V 0.78V 1.41V 2.03V 2.66V 3.28V 3.91V 4.53V 0.47V 1.09V 1.71V 2.34V 2.97V 3.59V 4.21V 5V 0-0.31V 0.94V 1.56V 2.19V 2.81V 3.44V 4.06V 4.69-5V August 2015  73 Front Panel Labels Version 2 of the receiver is housed in a UB5 plastic case. You will need to drill holes in the lid for the LEDs & piezo buzzer. SILICON CHIP Driveway Monitor Receiver    . 12V DC 100mA + Fig.17: this full-size artwork can be used as a drilling template for the Version 2 case lid. You can either copy it or download it as a PDF file from the SILICON CHIP website. and one directly above the piezo transducer to let the sound out. You can either copy and use Fig.17 as drilling template or you can simply measure the hole locations and then mark their positions on the lid (the artwork is also available for download as a PDF file from the SILICON CHIP website). Drill 3mm the holes for the LEDs and a 6mm hole for the piezo transducer. Testing (both versions) Before applying power, make sure that IC1 is out of its socket and that all parts are correctly orientated. That done, apply power from a 12V DC plugpack and check that there is 5V between pin 1 of IC1’s socket and . Departure + + Arrival + the GND PC stake (4.85V to 5.15V is acceptable). A reading below 4.85V could mean that there is a short circuit somewhere or an electrolytic capacitor could be the wrong way around. If the 5V supply is correct, disconnect power and plug IC1 into its socket (make sure it’s correctly orientated). Once it’s installed, reapply power and adjust VR1 to set the receiver’s identity by monitoring the voltage on TP1. Typically, VR1 is set fully anticlockwise to select identity 1. If you require a different identity (eg, to match a second detector unit), set it to match the detector as shown in Table 3. VR2 sets the alert duration. For Version 1, this is the time period be- Modified Sampling Rate For Indentites 5-8 Recent testing on the Driveway Monitor has shown that a vehicle can, on rare occasions, slip past the sensor unit undetected. To do this, the vehicle has to be travelling at over 20km/h and it has to pass the detector between the 300ms sampling intervals. This will not be a problem for most household driveways but it could be a problem on rural driveways where speeds can easily exceed 20km/h. To overcome this problem, we have increased the sampling rate to 150ms for identities 5-8 (ie, where TP1 is set 74  Silicon Chip for over 2.5V). So if vehicle speeds are likely to exceed 20km/h, set the unit to one of these higher identities. Identities 1-4 retain the standard 300ms rate. A disadvantage of the 150ms sampling rate is that quiescent current from the AA cell increases from about 3mA to 6mA. Correction: the parts list for the detect­or unit (see July 2015 issue) incorrectly lists IC1 as an AD723AN. It should be an AD623AN, as shown on the circuit. The front-panel labels are optional. They can be made by downloading the relevant PDF files from the SILICON CHIP website and then printing each one as a mirror image onto clear overhead projector film (use film that’s suitable for your printer). By printing mirror images, the toner or ink will be on the back of each film when it’s fitted. The labels can be secured using clear silicone adhesive. Alternatively, you can print onto a synthetic Data­flex sticky label if using an inkjet printer or onto a Datapol sticky label if using a laser printer. (1) For Dataflex labels, go to: www.blanklabels.com.au/index. php?main_page=product_info& cPath=49_60&products_id=335 (2) For Datapol labels go to: www. blanklabels.com.au/index.php? main_page=product_info&cPath =49_55&products_id=326 tween when relay 1 briefly turns on and closes the remote’s ON contacts to when relay 2 briefly turns on and closes the remote’s OFF contacts (ie, it determines how long the remote mains socket is switched on). This time duration ranges from about 20s when VR2 is set fully anticlockwise to about five minutes when VR2 is fully clockwise. You can quickly set the duration by monitoring the voltage between TP2 (ie, VR2’s wiper) and TP GND. Adjust VR2 for 5V on TP2 for five minutes, 2.5V on TP2 for two and a half minutes and 1V on TP2 for one minute, etc. Alternatively, for Version 2, VR2 adjusts the length of the entry and exit tones from 1-5s. Each indicator LED then lights for the length of its corresponding tone and stays on for about 15s after the tone ceases. All that remains now is to check that the unit is triggered whenever a car passes by the detector unit. If the unit fails to trigger or is unreliable, check that the detector unit is functioning properly as outlined in its installation procedure above. If that’s OK, check that the detector and receiver identities match. Finally, if you still have problems and the antennas are inside the cases, feed them outside and straighten them out to improve the range. They should also be orientated the same way; ie, SC both vertical or both horizontal. siliconchip.com.au