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Multi-sector home burglar alarm Looking for a versatile home burglar alarm? This unit features variable exit & entry delays, alarm driver circuitry, timed & latched outputs, and two separate sector inputs. A separate board allows you to add additional sector inputs as required. By GREG SWAIN House break-ins are still a problem in our major cities, despite the efforts of police and the various Neighbourhood Watch schemes. It's the portable items that the thieves are after, typically VCRs, cameras, power tools and, of course, cash and jewellery. Although the financial losses are 30 SILICON CHIP usually covered by insurance, it's never nice knowing that a stranger has intruded into one's home. The problem is, many homes present a "soft" target for thieves and even those that are securely locked won't deter a professional thief. To stop the professional thief, you need to take more positive measures and an electronic alarm system is probably the best approach (short of turning your house into a fortress). However, to be effective, the alarm must be correctly installed, it must not false alarm, and it must automatically reset after 10 minutes to meet noise pollution requirements. Most householders elect to have their alarm system professionally installed but that's usually fairly expensive. Often, there's not much change out of $1000. And even if you elect to do the installation yourself, a so-called "budget" 4-sector alarm will set you back about $200 (without sensors), although admittedly it will come in a lockable steel case and include provision for a backup battery. Left: this photo shows the alarm module, together with an add-on sector board. Also shown are some of the devices that you can use with the module: a horn speaker, a flashing blue light, and a passive infrared detector. But what if your budget won't extend to a commercial alarm, or you object to paying for fancy features that you don't really need? Most homes require only a basic alarm which is capable of monitoring just a couple of sectors - four at the most. With this project, you can tailor a home burglar alarm to exactly suit your needs. It includes all the essential features of a comprehensive alarm system but at a budget price. What's more, it can be used with a variety of sensors and can be easily expanded as your budget allows. Main features In its most basic form, this new home burglar alarm consists of a single PCB. This board includes two sector inputs and all the control circuitry for the alarm timer, adjustable entry & exit delays, LED status indicators and the siren driver. On its own, this module can form the basis of a very effective 2-sector home burglar alarm. All you need add are a keyswitch [to arm and disarm the circuit), a horn speaker, the appropriate sensors, and a 12V DC power supply. Depending on the sensors chosen, it could cost you less than $200 for the complete installation. The circuit is armed/disarmed using a simple keyswitch and the entry and exit delays can be independently set anywhere from 0-80 seconds using trimpots. This should provide more than ample time to leave or re-enter the house. If either sector is triggered, the alarm will sound for the permitted 10 minutes and then automatically reset. The sector that triggered the alarm is then disabled [to prevent repetitive false triggers in the case of a faulty sensor) but the alarm can still be retriggered by the remaining active sector(s). In addition to the siren output, there are also timed and latched Resistive Loop Sensing One important feature of the circuit is the use of resistive loop sensing. This simply means that 10k0 resistor is included somewhere in the input loop to each sensor. By doing this, the alarm will be triggered if any attempt is made to disable the loop by cutting it or shorting it with a jumper lead. Each sector input stage is identical and can be used with any sensor that has normally closed (NC) or normally open (NO) contacts. These include microwave & infrared detectors, pressure mats, window foil strips, light beam relays and panic switches. In fact, you can use any type of sensor that has a switched output. Fig.1 shows how the various types of sensors are wired into the alarm circuit. The alarm is triggered by either an open circuit or short circuit at a sector input; ie, if one of the sensor outputs changes state. a ·•~™ INPUT (a) NC SWITCHES IN SERIES :~M INPUT (b) NO SWITCHES IN PARALLEL (c) NO ANO NC SWITCHES Fig.1: these diagrams show how to wire sensors with normally closed and normally open contacts. Note the 10kn resistor in the wiring loop. relay outputs. could be used blue light, for timed output switch on a floodlights. The latched output to drive a flashing example, while the could be used to separate siren or Sector board Need more than two sectors? No problem. To cater for this requirement, a separate "sector board" has also been designed. This compact board carries just a handful of parts and has inputs for two extra sectors. You can add as many of these sector boards to the main control module as you like. All external connections to the alarm module are made via screw-type terminal blocks, so installation is easy. Note the 6-way wiring bus at bottom, left. This runs to the optional add-on sector boards. JUNE 1990 31 PARTS LIST 1 PC board, code ZA-1452, 140 x 106mm 2 12V SPDT relays (DSE Cat. S-7120) 1 12-way PC terminal block 1 3-way PC terminal block 2 SPDT miniature toggle switches 2 fuse clips 1 3A fuse 2 2 .2MO horizontal mount trimpots Semiconductors 1 LM339 quad comparator (IC1) 1 4049 hex inverter (IC2) 1 4027 dual JK flipflop (IC3) 1 4060 14-stage binary counter (IC4) 2 4011 quad NANO gate (IC5,IC8) 1 4020 14-stage binary counter (IC6) 1 4516 presettable binary up/down counter (IC?) 1 556 dual timer (IC9) 1 7808 3-terminal regulator 4 BC548 NPN transistors (Q1 ,Q4,05,06) 1 BC328 PNP transistor (02) 1 BD681 Darlington transistor (03) 5 1N4 148 diodes (D 1 ,D2,D3,D4 ,D5) 2 1N4002 diodes (D6,D7) 2 red LEDs (LED 1 , LED 2) 1 green LED (LED 3) 1 yellow LED (LED 4) Capacitors 1 1OOµF 16VW PC electrolytic The sector boards are easily wired into circuit by means of a 6-way wiring bus that's brought out to opposite edges of each board and to one edge of the main board. To add the extra sectors, you simply strap the boards together in daisychain fashion using plastic cable ties and install six wiring links. Note that all sectors, both on the main control board and on individual sector boards, can be wired for instant or delayed triggering. It all depends on how you install a single output diode for each sector. Each sector also features an enable/disable switch and a LED status indicator. The switches 32 SILICON CHIP 2 5 4 6 1 33µF 1 OV tantalum 1 OµF 16V PC electrolytic 1µF 50V PC electrolytic 0.1 µF monolithic .0015µF polyester Resistors (0.25W, 5%) 4 220k0 1 8.2k0 8 1 OOkO 2 2.2k0 4 22k0 5 1 .5k0 2 12k0 1 2700 5 10k0 Test Resistors 1 1 kO (for testing siren) 2 1 OkO (for terminating sector inputs) Sector board only 1 PC board, code ZA- 1453 , 46 x 106mm 2 SPOT miniature toggle switches 1 3-way PC terminal block Semiconductors 1 LM339 quad comparator (IC1) 1 4049 hex inverter (IC2) 1 4027 dual JK flipflop (IC3) 2 1N4148 diodes (01 ,02) 2 red LEDs (LED 1, LED 2) Capacitors 5 1OµF 16VW electrolytic 2 1µF 50VW electrolytic 3 0.1 µF monolithic Resistors (0.25W, 5%) 4 100k0 2 10k0 2 12k0 2 2.2k0 1 8.2k0 2 1 .5k0 allow you to isolate sectors as required. In this way, some areas of the house can be used while others remain active; eg, the internal alarm sectors can be disabled while the perimeter sectors remain active. A LED indicator lights whenever a sector is triggered and remains lit even after the alarm has timed out. It also remains on after the alarm has been disarmed by the keyswitch and goes out only when the circuit is armed again. That way, you can tell whether or not the alarm has triggered in your absence (due to an intruder or a faulty sensor) and take the appropriate measures. No battery back-up To keep the project as simple as possible, the basic control module doesn't include battery back-up. That problem's easily fixed however, and we'll be describing a battery back-up and mains supply board in a subsequent issue. We'll also be describing a keypad entry system. So you can make this project as simple or as comprehensive as you like - it's up to you. Circuit details To make it easier to follow, we've split the circuit into two separate diagrams. Fig.2 shows the sector input & latching circuitry while Fig.3 shows the main control circuitry which includes the alarm timer, exit & entry delay circuits and the siren driver. Let's deal first with the sector input and latching circuitry (Fig.2). As already mentioned, this circuit provides two inputs and is included along with the control circuitry on the main PC board. It is also duplicated on each of the separate 2-input sector boards. Each input circuit employs two op amp comparators wired in a window detector configuration. ICla and IClb form a window comparator for input 1, while IClc and ICld form a window comparator for input 2. Note that the circuitry for each input is exactly the same so we'll just concentrate on the circuitry for input 1. A voltage divider consisting of two 10k0 resistors and a 8.2k0 resistor sets the upper and lower threshold voltages on the comparator inputs. These voltages are + 5.1 V and + 2.BV and are applied to pins 9 and 10 respectively. The remaining two inputs of ICla & IC1 b [pins 8 & 11) normally sit at about + 4V (ie, in the centre of the window) by virtue of the voltage divider formed by a 12k0 pullup resistor, the 2.2k0 input resistor and the 10k0 resistor in the external sensor loop. The comparators employ open collector outputs which means that they can only pull low. Normally, however, the comparator outputs (pins 13 & 14) are held high by a 100k0 pullup resistor and so pin 6 of IC2a sits low. +BV + 10 16VW+ 0.1J +BV 10k 12K 100k N:3a ,,__ _ _ >o''---=t3 C 4027 K INPUT 1 2.2k 7 +" 01 1N4148 QF2--ll---1--14t-+--+---. S + 16VWI: 0.1+ 8.2k ~ GNO +av ~ +BV +BV + 10 16VW+ 12k +BV 10 + 10 16VV.I i J 01! 12 R 10 ~ D2 1N4148 + 10 16VW+ 10k ~ li! "' MULTI-SECTOR BURGLAR ALARM CONNECTION BETWEEN BOARDS SECTOR CIRCUIT Fig.2: the sector input & latching circuitry. ICla & IClb form a window detector. When a sensor triggers, the window detector output switches low and clocks JK flipflop IC3a via IC2a. This toggles Q-bar of IC3a low and, in turn, pulses either the instant or delayed trigger inputs to the control circuit low via a lµF capacitor & D1. IClc, ICld & IC3b function in the same man_ner. Now consider what happens if a sensor triggers and shorts the input to ground. When this happens, pins 8 & 11 are pulled down to 1.2V which is below the lower window voltage on pin 10 of IClb. The output (pin 13) of ICl b thus switches low and so pin 6 of IC2a switches high and clocks JK flipflop IC3a. Similarly, if the input goes open circuit, pins 8 & 11 are pulled to + BV which again is outside the window voltage limits. In this situation, ICla switches its pin 14 output low and so pin 6 of IC2a goes high and clocks IC3a as before. IC3a provides the sector control logic. As shown in Fig.2, its R (reset) and J inputs are connected to the reset and retrigger lines of the 6-way wiring bus. This 6-way bus is linked to the main control circuit and to all other sectors. When the alarm is armed, the control circuit pulls the reset line high for the duration of the exit delay. This prevents IC3a (and the flip flops in the other sectors) from triggering during the exit delay and resets it so that Q is low and Q-bar (pin 2) is high. At the end of the exit delay, the reset line goes low again and, because the J input is normally held high by the retrigger line, the flipflop is now free to toggle. When the sector is tripped, IC3a is toggled by the clock pulse from IC2a and latches its Q-bar output low. Thus, a negative-going pulse is generated at the sector output via the lµF capacitor and diode Dl. Depending on the linking option chosen, this pulse is applied to either the instant (I) or delayed (D) trigger lines of the 6-way bus and triggers the alarm circuit. As soon as the alarm triggers, the retrigger disable line goes low and disables the JK flipflops in the other sectors (eg, IC3b). This prevents these sectors from retriggering the alarm timer while the siren is on and thus ensures that the total alarm period is kept to 10 minutes. At the end of the alarm period, the retrigger disable line goes high again and rearms the remaining sectors. Sector 1, however, remains disabled because IC3a latches and thus ignores further clock pulses from IC2a. This sector is therefore unable to retrigger the alarm and remains in this state until IC3a is reset by rearming the alarm circuit (ie, during the next exit delay). LED 1 provides status indication for the sector circuit and is driven by IC3a's Q-bar output via parallel inverters IC2c & IC2d. Thus, when Q-bar switches low, the outputs of the inverters switch high ahd LED 1 lights to show that the sector has been tripped. The LED then remains on until IC3a is reset. So IC3a has four functions: (1) it disables the sector during the exit JUNE 1990 33 delay; (2) it disables the sector after it has been triggered so that it cannot retrigger the alarm; (3) it stops other sectors from triggering the alarm while the siren is on; and (4) it latches a LED indicator circuit to show that the sector has been triggered. Switch Sl allows the sector to be disabled if required. If the switch is closed, pin 13 of ICl b switches low and pin 6 of IC2a remains high. Thus, when the circuit is armed, no clock pulses can be applied to IC3a and so the sector is disabled. Sl will also trigger the sector if it is closed after the alarm is armed and this provides a useful test feature. Control circuit Now take a look at Fig.3 which shows the main control circuit. At the very heart of this circuit is IC7 which, together with IC4 & IC6, forms a 10-minute timer. IC7 is a 4516 presettable binary up/down counter and has been wired here to count down (pin 10 at GND). Normally, the count is at 0000 which means that COUT (pin 7) is low. Pin 7 of IC7 is coupled to the base of Q4 (via a 22kn resistor] and also drives NAND gate ICBb. Because IC8b is wired as an inverter, its pin 10 output will be high during this time and this holds IC4 & IC6 in the reset condition (ie, with all outputs at logic OJ. In addition, ICBb's output provides the retrigger disable line that runs to the J inputs of IC3a & IC3b in the sector circuitry (Fig.2). IC7 is only free to count down when its carry in (pin 5), preset enable (pin 1) and reset (pin 9) inputs are all low but first a value must be loaded into the counter via the parallel PO-P3 inputs. This is done by briefly taking the preset enable high when the alarm is triggered. Because the PO-P3 inputs are all connected to the + 8V rail, this pre sets the counter to 1111 (15 ]. Note that IC7's Ql-Q4 outputs are not shown, since they are not used in this circuit. When the alarm is armed, the reset pin is normally held low via a 220k0 resistor while the preset enable is controlled by the output of NAND gate IC8a. If a trigger pulse is received from one of the sectors (ie, the alarm is triggered), ICBa's output briefly switches high and loads 1111 into IC7 via its parallel (PO-P3) inputs. GOUT now immediately switches high and turns on Q4 and relay 1 to provide the timed output. At the same time, pin 10 of IC8b switches low and this does three things. First, it toggles latched flipflop IC8c & ICBd, thus turning on Q5 and relay 2. Second, it pulls the retrigger disable line low to disable the sector circuits as described previously. And third, it releases the reset on IC4 and IC6 to enable the clock circuit. IC4 (4060) and IC6 (4020) are both 14-stage ripple carry binary counters and are almost identical, the main difference being that the 4060 has provision to connect external RC components to form an oscillator. In this circuit, the frequency of oscillation is set to 26kHz by the RC values on pins 9, 1O & 11. This frequency is divided by 16,384 Where to buy the kit This project was developed by Dick Smith Electronics and is available from all DSE stores or by mail order from PO Box 321, North Ryde, NSW 2113. You can also order by phone on (02) 888 2105 or, if you are outside the Sydney area, on (008) 22 6610. The kit consists of an etched PC board plus all the on-board components (note: does not include the keyswitch and horn speaker) . Prices are as follows: Main control module (Cat. K-8401) ................... ................ $39.95 Optional sector module (Cat. K-8400) .......................... .. ... $12.95 Postal orders should include another $4.50 for p&p. Please quote the catalog numbers when ordering. Note: copyright of the PCB artworks associated with this project are retained by Dick Smith Electronics. 34 SILICON CHIP (214) at IC4's Q14 output and clocks IC6 which divides by a further 64. This produces a .025Hz clock signal on pin 15 of IC7; ie, one clock pulse every 40 seconds. Each time a clock pulse is received, IC7 counts down by 1 and so it takes 10 minutes (15 x 40 seconds) to go from the preset value of 1111 (15) to 0000. When 0000 is reached, COUT goes low again, Q4 (and thus relay 1) turns off, and pin 10 of IC8b switches high. This resets IC4 & IC6 and rearms the remaining active sectors via the retrigger disable line. Note that a linking option is shown on Fig.3 for the retrigger disable line. Normally, this link should be installed as shown to prevent the circuit from retriggering during the alarm period. However, there may be applications where retriggering is a desirable feature and this can be achieved by isolating the retrigger disable line from the output of IC8b and connecting it to the + 8V rail. In practice, this simply involves connecting the link to point R instead of point N. Siren circuit As well as providing the clock signal, IC4 also provides two signals to drive the siren circuit. These signals are derived from the Q4 and Q5 outputs and are at 1625Hz and 812.5Hz respectively. These signals are gated by IC5a, IC5b and IC5d and switched at a 6.35Hz rate by the Q12 output. When Q12 is high, the 1625Hz signal from output Q4 is gated via IC5b. However, when Q12 is low, pin 3 of IC5c switches high and the 812.5Hz signal from Q5 is gated via IC5a. IC5d gates the signals from IC5a & IC5b and switches transistor stage Qt. This in turn drives Q2 which then drives power transistor Q3 and the siren. At the end of the to-minute alarm period, IC4 is reset as described above and its Q4, Q5 & Q12 outputs all go low. This switches the output of IC5d low and so transistors Ql, Q2 & Q3 all turn off and the siren stops. Exit delay & reset An exit delay is necessary to give you time to leave the house without HORN SPEAKER ... IRELAY1 7 ,-.-----+---------------+BV 1 7 012 04 5 .0015 Q 16 16 10 IC4 10 K4lo Q6 RST 4 15 ~TIMED ~ OUTPUT 13 12 P1 PO 014 3 10k 4 16 P2 IC7 4516 CLK 11 4060 ':' 22k 11 RST 12 .,. RELAY2 I LINK N LINK RL-+sv ~ LATCHED ~ OUTPUT +av 1 10 220k ~----__..__ _ _.....,_ _ _..,__+av VR1 2.2M .,. 14 +12V 13 220k F1 IC9a 556 12 DELAYEDo-_ _ __.;_ 3A 12 i,::.:.......,_ _ _.n..~....n+12v +aV DC 11INPUT ..("'°DY __, .,. TRIGGER +av ENTRY DELAY RESETO----------------=:i.----------. _;_ IC9b GND / PLASTIC SIDE B EOc ~ VIEWED FROM BELOW + 33 16VWJ 0.11 D4 1N4148 1 ARM 05 1N4148 DISARM 0 EXIT DELAY EICII MULTI-SECTOR BURGLAR ALARM KEY SWITCH CONTROL CIRCUIT Fig.3: a 10-minute timer formed by binary counters IC4, IC6 & IC7 is at the heart of the control circuit. IC9a provides the delayed triggering function, while IC9b provides the exit delay by holding the counters and the sector flipflops reset for a set period of time. setting off the alarm. Its function is to disable the alarm during the exit period and this job is performed by IC9b. IC9b is one half of a dual 556 timer IC and is wired as a monostable. Its output at pin 5 controls the reset line to IC7 via D4. Normally, this output is low and thus has no effect on the circuit. However, when the alarm is armed by switching S3 to GND, a negative going trigger pulse is applied to pin 6 of IC9b and to pin 6 of ICBd via a lµF capacitor. This does two things. First, it resets flipflop ICBc & ICBd so that Q5 and relay 2 turn off. Second, it triggers IC9b which immediately switches its pin 5 output high. This high on pin 5 pulls the reset line to IC7 high via diode D4, thus JUNE 1990 35 Fig.4: here's how to install the parts on both the main board and the add-on sector board. Make sure that all parts are correctly oriented and note that D1 & D2 can be connected to provide either instant or delayed triggering (see text). SECTOR INPUTS SECTOR INPUTS r - - - :;;,;-;~ ~ ~~ S3 KEY HORN TIMED LATCHED 12V -------;:~SW~IT~CH~~~§==T==~='='==:i~::j:'::::;-::-7 0 holding IC7 reset for the duration of the exit delay. It also pulls the reset line of the 6-way bus high to reset the sector flipflops (IC3a & IC3b). And finally, it turns on Q6 to light the exit LED (LED 4). LED 3 (armed) also turns on at this time, since its cathode now has a path to ground via its 1.5k0 current limiting resistor and keyswitch S3. The 33µF timing capacitor on pin 6 now charges via VR2 until the voltage across it reaches 2/3Vcc (Vee = 8V). When this happens, pin 5 switches low again and releases the reset lines so that the circuit is now armed. At the same time, Q6 turns off and the exit LED goes out. LED 3 remains on until the circuit is disarmed by switching S3 to the DISARM position. Pin 9 (reset) of IC7 is now pulled high via D5 and the 22k0 resistor associated with LED 3. This holds IC7 reset and thus disables the alarm timer as before. Entry delay IC9a is the other half of the dual 556 timer and is used to provide the entry delay. It is also wired as a monostable which means that its pin 9 output is normally low and the lµF output capacitor is fully charged. When a negative-going trigger pulse from one of the sectors is applied to pin 8, the monostable triggers, pin 9 switches high, and the 36 SILICON CHIP lµF capacitor quickly discharges via its associated 220k0 resistor. The 33µF timing capacitor now charges towards 2/3Vcc via VR1 and this charging period determines the entry delay. When the capacitor voltage reaches 2/3Vcc, pin 9 switches low again and pulls pin 13 of IC8a low via the lµF capacitor and D3. Pin 11 of NAND gate IC8a thus switches high and loads 1111 into IC7 to start the alarm timer as described previously. The lµF capacitor then quickly charges via D3 and the 220k0 and 100kn resistors, and pin 11 of IC8a switches low again to allow IC7 to count down. IC8a is used to gate the instant and delayed trigger pulses. Note that its inputs are normally held high by the 220k0 and 100k0 pullup resistors, which means that the preset enable of IC7 is held low until a trigger pulse is received. Diode D3 is necessary to protect IC8a from the voltage spike that appears on the positive terminal of the lµF capacitor whenever pin 9 of IC9a switches high. Power supply Power for the circuit is derived from an external + 12V source and is fed to a 7808 3-terminal regulator to obtain a + 8V rail. This regulated + 8V rail supplies all the ICs a))d prevents the circuit from self-triggering when the back-up battery takes over after a mains failure. The relays and horn speaker are powered directly from the + 12V rail to ensure reliable triggering and maximum sound output. Fuse Fl provides short-circuit protection for the + 12V supply while the 100µF, 10µF and O.lµF capacitors on the regulator input and + 8V rail to each sector provide supply line filtering and decoupling. Construction Despite the circuit complexity, this project is easy to build and get going. It was developed by Dick Smith Electronics and is available from this company as a complete kit of parts (for further details, refer to the accompanying panel). Fig. 4 shows the assembly details for both the main board and the optional sector board, and shows how they are linked together. The main board is coded ZA-1452 and measures 140 x 106mm. Before installing any parts, check the copper pattern carefully for possible defects. In particular, check for open circuit tracks and shorts between tracks due to incomplete etching. The parts can now be installed on the board. Install the wire links first , then install the fuse clips, resistors and capacitors. Use a digital multimeter to check the value of each resistor before it is in- SUPER JUNE-AUGUST 90 SPECIAL VHF REMOTE CONTROL - EA April 89 With our latest VHF transmitter • Proven reliable unit • Complete Tx kit and PCB with components for Rx kit. Tx battery included UNBEATABLE PRICE $49.90 for the pair EXTRA Tx $17.20 PIR MOVEMENT DETECTOR/ALARM EA May 89 Now supplied with a commercial case/lens/swivel base assembly. The optional interface kit lets you use it as a stand alone alarm, auto light control, auto door opener, etc. SUPER VALUE AT $39.95 for PIR kit $7 .95 for interface components. We can hold this price only for a limited time. PIR DETECTOR/LENS KIT [JI High quality " DUAL ELEMENT" pyroelectrical detector and small wide angle lens. For JUNE/AUGUST only $17.90 the set. Stock up now! THAT'S MORE THAN 30% OFF EHT POWER SUPPLIES The B0681 Darlington transistor is installed with its plastic side facing away from the relays while the leads of the regulator are bent at right angles so that its metal tab sits flat against the PCB. stalled and note the links that sit beneath relay 1, ICl, IC3 and IC4. The link connected to point N (near VRl) provides the retrigger disable option. As shown, this link will prevent the alarm from retriggering during the alarm period (ie, while the siren is on) and this is the option that will suit the vast majority of applications. If you do wish to provide for alarm retriggering during the alarm period, connect the link to point R instead of point N. Note that if the alarm does retrigger during the alarm period, the alarm timer restarts so don't use this option if you intend using a siren output or you could breach noise pollution laws. Now install the diodes. Make sure that they are all installed with the correct polarity and note that D6 and D7 should be 1N4002 types. Diodes Dl and DZ are wired to select either the instant or delayed triggering option for their corresponding sector inputs. If you want instant triggering, connect the anode of the diode to point I. If you want delayed triggering, connect it to point D instead. Fig.4 shows how the diodes are connected to provide instant triggering for input 1 and Slightly used but tested professional units . Fully regulated. Two types, 24VDC-3.5kV DC at SmA and 24VDC-15kV DC at 500mA. Both will work at reduced outputs down to 6VDC. Use for CROs, high voltage testing , night vision tubes , delayed triggering for input 2 but you should wire them to suit your requirements. The ICs and transistors can go in next. Note that IC3 faces in the opposite direction to ICl and ICZ. Push the transistors down onto the experimenting etc. $39.75 - ,3.5kV unit $44.90 - 15kV unit Limited stocks at these SPECIAL prices _ ···: · f_·.. ··. it/ ~,. £; LASER TUBES AT BARGAIN PRICES See our ads in Silicon Chip April 90 and EA May 90. We now also stock a collimator lens assembly which is used to maintain small beam diameter at long distances. $79.00 HIGH ENERGY IGNITION SYSTEM SC May 88 Uses high energy ignition IC made by Motorola. Proven reliable performer. Short form kit includes PCB and all semiconductors with instructions. ONLY $29.90 I MAINS MUZZLER - SC Jan 89 Filters mains and protects against high voltage spikes. Includes 40 joule varistor and AC capacitors. For all electronic equipment. Short form kit includes PCB and all compo nents as shown. SUPER PRICE $12.90 Why not buy two just in case? SERVICEMAN'S SPECIAL 1 0kV Diodes - $2.50 Late model TV tripler - $12.90 '"'.~.,..,.-· ~ ~_,.. ..·~ .. .,,...,'>'$ ~,_.,~,•h OATLEY ELECTRONICS The add-on sector boards carry just three ICs & a handfull of other parts. These are linked to each other & to the main control board by the 6-way wiring bus at bottom. JUNE 1990 37 PO BOX 89 OATLEY, NSW 2223 Telephone: (02) 579 4985 MAJOR CREDIT CARDS ACCEPTED Certttied p&p $4-$6 Aust; NZ add $2 Distri butors: Slightly higher prices may apply. MELBOURNE: ELECTRONICS WORLD - (03) 723 3860 BRISBANE: KINGSWAY ELECTRONICS - (07) 390 2399 The armed, exit & sector indicator LEDs are all mounted on the copper side of the main board, along with the sector disable switches. Mount the LEDs so that their tops line up with the threaded switch collars. board as far as they will comfortably go before soldering their leads and be sure to use the correct transistor type at each location. Make sure that all transistors are correctly oriented. Now install Q3 and the 7808 regulator. Q3 is installed with its metal face towards the relays while the leads of the regulator are bent at right angles so that its metal tab sits flat against the PCB. The top side of the PCB can now be completed by installing the trimpots, relays and the terminal connectors. Construction can now be completed by installing the switches and LEDs on the copper side of the board. Install the switches so that their leads go about half way through the board and check that they are straight before soldering. The LEDs should be installed so that their tops line up with the threaded switch collars (ie, about 22mm proud of the board). Take care to ensure that the LEDs are installed with the correct polarity. The flat on the LED body is adjacent to the cathode (K) lead. Use red LEDs for the sector indicators, a green LED for the alarm armed indicator (LED 3) and a yellow LED for the exit indicator (LED 4). 38 SILICON CHIP The optional sector boards (code ZA-1453, 46 x 106mm) can now be assembled in the same manner (see Fig.4). Don't connect the sector boards to the main board at this stage, however. That's best left until after the main board has been tested. Testing The following procedure should be followed to test the unit: (1). Connect a 10k0 resistor across each sector input (ie, between each outer terminal and GND) and set VRl & VR2 to mid-range. (2). Set the disable switches to OFF (ie, away from the LEDs) and connect the keyswitch and a 12V power supply (a plugback can be used for testing but not to drive the siren at full power). Note that relay 2 may turn on when power is first applied. (3). Switch the keyswitch to the ARM position. Check that LED 3 (armed) & LED 4 (exit) both turn on. LED 4 should then turn off at the end of the exit delay. (4). When LED 4 goes out, trigger a delayed sector using its disable switch. Check that the sector LED immediately turns on and that both relays operate at the end of the entry delay. Check that relay 1 drops out after about 10 minutes and that relay 2 remains latched (ie, outputs 8 & 9 shorted). (5). Rearm the circuit using the keyswitch and check an instantaneous sector. Check that both relays operate as soon as the sector is tripped. Check that other sectors cannot be tripped during the alarm period if theretriggering link is connected to point N. Alternatively, check that the alarm does retrigger and restart the alarm period if the link is connected to point R. (6). Connect the horn speaker via a lkO resistor (to stop you being deafened) and trigger the alarm. Check that the siren operates for 10 minutes when the alarm is tripped. (7). Connect the optional sector boards and check that all sectors can trigger the alarm (don't forget to terminate all sector inputs with a lOkO resistor). Adjust the entry and exit delays to the required periods using VRl and VR2 (you will have to rearm the alarm to check each period). Switching off The sector disable switches & indicator LEDs are also mounted on the rear of the sector board. Finally, remember that once the alarm has triggered, relay 2 and the tripped sector LED remain on even if the keyswitch is moved to the DISARM position. To reset these, first turn the keyswitch to DISARM, then briefly back to ARM, and then back to DISARM again (note: the exit LED will turn on for the period of the exit delay). ~