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Build the SurfSound Simulator If you often come home from work a bit frazzled, then you need the SurfSound Simulator. It produces the soothing sounds of waves rolling up your favourite beach. ~ · ··c;;cOCccC::.,.,q,,•..•,:.;; By DARREN YATES Most of us at one time or another have wanted to own some property on the beach. Just think-you come home from work, throw your trusty towel over your shoulder, and go for a swim in the "backyard". Or, if you prefer, you can just sit on the sand and listen to the waves rolling up on the shore, while you improve your tan! Unfortunately, most of us can't afford lhe price lags lhal go with such land. Nevertheless, the sounds of the surf do contain a relaxing, rhythmic quality about them - just the thing to unwind those nerves after a hectic day's work! It's also great if you have trouble getting to sleep at night, or any other time of the day. The SurfSound Simulator is the next best thing to owning a bit of that favourite beach and is half a million dollars cheaper into the bargain! It produces a sound that actually imitates the ebb and flow of the surf rolling up on the beach, including the occasional big 24 SILICON CHIP "dumper" that comes and drenches your towel - except in this case, you get the surf sound without the salt sea spray. The project uses no "hard to get" bits and fits neatly into a small plastic instrument case. If you have a reasonable junk box, you probably have most, if not all, of the parts already. The SurfSound has its own builtin speaker, or you can use the RCA socket at the back and feed the sound into your stereo system for an even more realistic effect. It runs off a 12VDC plugpack so you don't have to worry about mains wiring and it requires no setting up to get it to work. All you do is turn it on, set the volume and you're away. OK, enough of the hard sell! Let's take a look at how the SurfSound actually works. Block diagram To start with, let's look at the block diagram in Fig.1, which shows each of the different sections in the circuit. This will make it easier to understand the circuit diagram later on. The sound of the surf is very similar to white noise. That's the sound you hear coming out of your TV when you're not on a particular channel. We can generate that noise quite easily using a single transistor. However, because the surf doesn't have a constant volume, we have to find some way of varying the volume or "modulating" our noise source. By doing this, we can imitate the ebb and flow of the surf. If you sat down and plotted the sound level of the surf over a period of time, you would find that it resembled a triangular waveform. The sound steadily increases, hits its peak and then dies away again. In the block diagram, you'll see that there are not one but two triangle wave generators. The reason for this is to provide a degree of randomness to the sound level. With one generator, you only get the same wave crashing at a constant rate but with two, you get two waves rolling in at random. Both waveform outputs are fed into seperate modulators. To keep the circuit using only common parts, we used the humble diode to provide the modulation. We'll talk about how this is done a little later. The output from generator 1 is also fed to a peak amplifier. This amplifies the peak of the waveform to give a larger DC voltage than the triangle wave generator can produce. When we feed this voltage into another diode modulator, we produce the big "dump" when the wave hits the beach. All three diode modulators are capacitively coupled to the inverting input of an op amp stage. In operation, the three modulators vary the impedance from the op amp's inverting input to ground, thus changing the gain and therefore the sound level. The output of the preamplifier is fed to a low pass filter stage. Its job is to add realism to the sound by reducing the high frequency response. From there, the signal then passes to the power amplifier and thence to the loudspeaker. The circuit Refer now to Fig.2 which shows all the circuit details. The noise source is Ql which is a reverse- The Surfsound Simulator is built into a standard plastic instrument case. Notice the pattern of holes drilled into the lid to allow sound from the loudspeaker to escape. You can also feed the output into your hifi system. biased BC549C NPN transistor. Because the base-emitter junction of a transistor is very much like a zener diode, it suffers the same breakdown effect when a voltage is placed across it, thus producing a good source of white noise. This noise is capacitively coupled to the non-inverting input (pin 3) of op amp stage IC2a. ICla & IClb together form the first triangle wave generator, while IClc & ICld form the second. The first generator is responsible for a wave that is very close while thesecond produces a wave that crashes in the distance. Because the two are nearly identical, we'll just explain how one of them works and mention the slight differences between the two. If we look at the first generator, ICla forms a Schmitt trigger while IClb is connected as an integrator. Because it is a Schmitt trigger, ICla's output will be either high or low and so it either charges or discharges the 33µF capacitor at pin 6 of IClb via Dl, D2 and the two associated resistors. The resulting waveform at pin 7 of ICl b will be a sawtooth which rises faster than it falls. This gives the effect of the waves rolling up faster than they run back to the sea. Now take a look at the second generator based on IClc & ICld. PREAMPLIAER NOISE SOURCE ,___ _ POWER AMPLIFIER LOW-PASS ALTER TRIANGLE WAVE GENERATOR 1 DIODE MODULATOR 1 TRIANGLE WAVE GENERATOR 2 DIODE MOIHJLA TOR 2 DIODE MODULATOR 3 PEAK AMPLIAER Fig.1: the SurfSound uses two triangle wave generators to drive three diode modulator circuits. These then vary the gain of an op amp stage which amplifies a noise signal fed to its non-inverting input. The output of this op amp drives a low pass filter stage and a power amplifier. OCT0BER1990 25 The only difference between the two circuits is that the second generator has a smaller char ging resistor (100k0 vs 220k0). This has two effects. First, it helps to make the two waves more random in nature and second, it provides the second wave with a faster " roll up" time. The 0.1µ,F capacitors at the outputs of ICl a and IClc r emove "clicks" from the audio output which would otherwise a ppea r due to the switching a ction of the Schmitt triggers. Diode modulators The outputs of the two triangle wave generators are used to drive the diode modulator circuits shown in the block diagr am (Fig.1). The circuit technique used here will probably be new to a number of readers so we'll go thr ough it in some detail. It relies on the fact that the conductivity of a diode varies with the voltage across it; ie, a diode that has 0.6V across it will conduct more current than one with only 0.2V across it. There are thr ee modulators in the circuit, centred around diodes D5 to DB (diodes D5 and D6 run from the same point and so are counted as one modulator). The first generator drives diodes D5 and D6, the second drives D7 and the. peak amplifier operates DB. Again, each of these is similar in operation, so we'll only describe one in detail. On the cathode lead of each of these diodes is a voltage divider. In the case of D7, for example, there is a pair of 100k0 r esistors. These set the offset voltage for this modulator to 6 volts. Different r esistance values a r e used in the voltage dividers of the other modulators. These set the offset levels to different values to ensure the correct turn-on sequence. For diode D7, this means that the output of its triangle wave generator must rise above 6V before the diode has enough foward bias to conduct. This output is coupled to the anode of D7 via a 47k0 resistor and also to the inverting input of preamplifier IC2a via a 0.12µ,F capacitor. While the voltage from ICld re- PARTS LIST 1 plastic instrument case, 150 x 160 x 65mm 1 PCB, code SC08109901 , 140 x 120mm 1 front panel label, 142 x 55mm 1 rear panel label, 142 x 45mm l 1 OkO log potentiometer 1 knob to suit 1 screw-mounting RCA socket 1 2. 1 mm DC power socket 1 5mm LED bezel 1 SPST toggle switch 5 PC pins 1 1 2V DC plugpack 4 clamps for loudspeaker (see text) 1 4-inch car speaker (Jaycar Cat. AS-3008 or equivalent) Semiconductors 2 1 1 1 1 8 26 LM324 quad op amps (IC1-,2) 7812 3-terminal regulator BC549C NPN transistor (01) BC338 NPN transistor (02) BC328 PNP transistor (03) 1 N91 4 silicon signal diodes (D1-D8) SILICON C HIP 1 5mm red LED (LED 1) Capacitors 3 1 2 2 1 1 1 1 2 5 1 1 1 4 70µ,F 16VW PC electrolytic 330µ,F 25VW PC electrolytic 100µ,F 16VW PC electrolytic 33µ,F 25VW PC electrolytic 1 Oµ,F 63VW PC electrolytic 1 Oµ,F 25VW PC electrolytic 2 .2µ,F 25VW PC electrolytic 0 .47µ,F 63VW PC electrolytic 0.12µ,F metallised polyester 0. 1 µ,F metallised polyester .056µ,F metallised polyester .018µ,F metallised polyester .0012µ,F metallised polyester Resistors (0.25W, 5%) 1 1MO 2 330k0 1 220k0 1 150k0 9 120k0 1 5 1 OOkO 4 68k0 3 2 1 1 2 1 2 47k0 33k0 1 2k0 8.2k0 4.7 k0 1 kO 10 Miscellaneous Hookup wire, solder, screws, nuts, washers etc. mains below 6V, the diode is reverse-biased and the 0.1 2µ,F capacitor sees a large impedance to the ground line. However, when the voltage rises above 6V, the diode begins to turn on, which decreases its AC impedance. The 0.12µ,F capacitor thus sees a progressively lower impedance to ground as the voltage across the diode increases. Because op amp IC 2a is connected as a non-inverting amplifier, these impedance variations directly control its gain. If the impedance goes down, the gain goes up. Conversely, if the impedance goes up, the gain goes down. Thus, the diode modulators control the gain of the preamp stage to vary the sound leveL When the voltage across D7 reaches 0.6V, the diode appears as a short circuit to the capacitor and the impedance to ground is now set by the 8.2k0 resistor connected to D7's anode. The 100µ,F capacitor, in conjunction with the 8.2k0 resistor, forms a high-pa ss filter which rolls off the response below O.lHz. D5 and D6 work in similar fashion but have offset voltages of 5.45V and 7.2V respectively. Note also that D6 controls another highpass filter. This consists of a 4.7k0 resistor and 0.1µ,F capacitor, and has a cutoff frequency of 340Hz. Because of their different offset voltages, D6 comes into operation before D5 (which controls lower frequencies) so that we get a realistic "whooosshhh" sound as the wave breaks. Peak amplifier In addition to the above, the gain of IC2a is also controlled by diode modulator DB, which is driven by peak amplifier IC2d. This in turn is driven from the output of ICl b . The bias for IC2d's inverting input (pin 13) is set to about 7V by the 33k0 resistor & the two 100k0 resistors. Thus, the output of IC2d remains low until pin 7 of ICl b Fig.2: the circuit .includes all the elements shown in Fig.1. ICla,b & IClc,d are the triangle wave generators, IC2d the peak amplifier, & D5/D6, D7 & D8 the diode modulators. The latter vary the gain of IC2a which amplifies noise signals from Qt. ► N "-I 0 ...... c.o c.o ::0 t'1 tJ:j 0 '-l n 0 I 120kt 120kS +12V ~ +12V I I V" . ........ •1?V I ® 03 47k 330k hh u u 100k +12V ":' • -. + 33 25VW 100kt •PM 33k I .• r-...... l +m~ 100k - I ,,.-:-.. 01l D I I .~7k 150k4 100k! .J: (!) ":' I I 100 16VWL. + 68k 100k +12V~ OU 100k + ---+ 0.47 63VW D.1-+ I 1 +12v -- 8 I VIEWED FROM BELOW EQc .J.:' 330 25VW+ .. l r -! 120k I ,,.,,.,.,. 68k 100 16VWJ D5 ...11/" l I I I - - 0.12 I I I VOLUME VR1 10k GNO ,~oo, ~. .,. l ·--··_r ""t, ~ I ~ + 0.1+ I .018! rn E 02 BC338 ~ I B -'=K .,. Sil SPEAKER +12V ·1 470 16VW +12V ~OUTPUT l I I + I 16VWJ 470 IN~OUT I --····· SURFSOUND SIMULATOR ov-¼ 0 V~ ~,,. I J: 2.2 25VW+ k - ~ +12V DC PLUGBACKO--O .0012 1.----J 1M +12V CAPACITOR CODES OUTPUT S1rs---(r-:112VDC l;J' ~ + ~ 0 ~INPUT - g :f ~ _...; ''""~ ~ "' D 30 · 33uF ~. , ~ \..I ~ ~0.47uF W 0 Value IEC Code EIA Code 0.12µF 0 .1µF .056µF .018µF .0012µF 120n 100n 56n 18n 1 n2 124 104 563 183 122 adds to the realism of the sound. After that, the signal is passed onto the RCA socket and also to a lOkQ volume control pot which feeds the internal power amplifier. IC2c, Q2 and Q3 form the power amplifier stage. Q2 and Q3 buffer the output of the op amp to provide current gain and are connected into the feedback loop to reduce crossover distortion. Power for the circuit is derived from a 12V DC plugpack supply. This feeds a 7812 3-terminal regulator which in turn delivers a regulated 12V rail to feed the op amps. The 470µF and O. lµF capacitors provide filtering for the regulator while LED 1 provides visual indication that the power is on. Note that although the plugpack supply delivers a nominal 12V output, its output will actually be much higher than this typically 16-17V. This is quite sufficient to drive the 7812 regulator. Construction A VR1 LED1 Fig.3: be sure to check component orientation carefully when wiring up the PC board. Note that the 0.1µ.F capacitor between IC1 & IC2 should be laid flat on its side to provide clearance for the loudspeaker. reaches this threshold level. At this point, IC2d amplifies the signal to produce a faster, steeper waveform. This produces the big "dumper" that crashes onto the beach. Low-pass filter IC2a amplifies the white noise generated by Ql. From there, the signal is fed to IC2b which functions as a non-inverting amplifier 28 SILICON CHIP with a gain of 11. A .0012µF capacitor in the feedback loop of IC2a rolls off the response above 130Hz, while the 2.2µF capacitor in the feedback network of IC2b rolls off the low frequency response of this stage below a few Hertz. Following IC2b is another lowpass filter stage consisting of a 4.7k0 resistor and lOµF and 0.018µF capacitors. This further reduces the higher frequencies and Most of the components for the SurfSound are mounted on a PC board coded SC 08109901 (140 x 120mm). This is housed in a standard plastic instrument case measuring 160mm deep, 150mm wide and 70mm high. Before you commence assembly, carefully check the PC board for shorts or breaks in the tracks. Any faults should be corrected at this stage. Once you're satisfied with this, take a look at the wiring diagram [Fig.3). It shows how the components should go in. Begin by installing PC stakes at all the external wiring points on the board. Once this is done, you can install the wire links, resistors and diodes, in that order. Make sure that each diode is correctly oriented. If you are unsure of the colour The PC board is screwed to integral pillars in the base of the case while the loudspeaker is secured to the lid using four aluminium clamps (see text). Note the 7812 regulator - its tab faces the front. coding of the resistors, use a multimeter to check the values. The next step is to to install the polyester (greencap) capacitors. Note that the O. lµF capacitor between ICl & IC2 should be laid flat against the board (ie, bend its leads at right angles) so that there is sufficient clearance for the loudspeaker. Once you've got this done, solder in the electrolytic capacitors but make sure that you've got the polarity correct. Finally, install the transistors, I Cs and 3-terminal regulator. Again, make sure that they are installed correctly, then check over the board again in case you missed something. In particular, check that the correct transistor type has been installed at each location. Now attach the Dynamark labels to the front and rear panels, then drill and ream out the mounting holes. The only hole that may cause difficulty is the hole for the DC power socket. The best way to get the hole size just right is to drill a small pilot hole and then use a tapered reamer to enlarge the hole until it's slightly smaller than the perimeter of the socket, Finally, the hole can be filed to shape until you RESISTOR CODES D D D D D D D D D D D D D D D No 1 2 1 1 9 15 4 3 2 1 1 2 1 2 Value 1MQ 330kQ 220kQ 150k0 120k0 100k0 68k0 47k0 33k0 12k0 8.2k0 4 .7k0 1 kQ rn 4-Band Code (5%) brown black green gold orange orange yellow gold red red yellow go1d brown green yellow gold brown red yellow gold brown black yellow gold blue grey orange gold yellow violet orange gold orange orange orange gold brown red orange gold grey red red gold yellow violet red gold brown black red gold brown black gold gold 5-Band Code (1%) brown black black yellow brown orange orange black orange brown red red black orange brown brown green black orange brown brown red black orange brown brown black black orange brown blue grey black red brown yellow violet black red brown orange orange black red gold brown red black red brown grey red black brown brown yellow violet black brown brown brown black black brown brown brown black black silver brown OCTOBER 1990 29 ~S~4- BOARD SOLUTIONS Pty Ltd EXTERNAL FLOPPY DISK DRIVES 10MHzXT,(640K)OKRAM M1010 115.00 10MHzXT,(1MB)OKRAM M1000 149.00 31 MHz XT286 OK RAM M1020 225.00 Baby 286 12MHz OK RAM M2015 399.00 Baby 286 12MHz OK RAM VLSI M2030 449.00 Baby 286, 12MHz VLSI OK Neat M2020 499.00 286, all-in-one, OK RAM M2010 545.00 16MHz NEAT 286 OK RAM M2040 599.00 20MHz 2~6 OK RAM M2045 845.00 16MHz 386SX, OK RAM M3000 895.00 25MHz 386, 32K Cache, OK Neat M301 o 1995.00 33MHz 386, 32K Cache, OK M3 o2 o 2795 _00 ,------------------------., I· CHIPS 1M RAM Chip - 100nS 1M RAM Chip - 80nS 256K RAM Chip - 1OOnS 256K RAM Chip - sons 8087-2, 8MHz Co-Processor 29300 29380 29400 29480 29500 29.95 32.95 7.95 8.95 275.00 4X256KRAMChip, 100nS 29200 4 X 64K RAM Chip, 120nS For . 29212 VGA card 64K RAM Chip - 120nS 29112 NEC V20Chip 29000 NEC V20 Chip, 10MHz 29010 29020 NEC V30 Chip, 10MHz 64K RAM Chip - 1OOnS 29210 80387SX 16MHz Co-Processor 29540 64K 1OOns RAM Chip 29210 2C87-8MHz (equiv 80287/8) 29550 2C87-10MHz (equiv 80287/10) 295Sb 2C87-12MHz (equiv 80287/12) - zg-550 29565 2C87-20MHz 29570 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20) 29575 3C87-25MHz (equiv 80387/25) 29580 3C87-33MHz (equiv 80387/33) 29585 SIMM Module, 1MB 80ns 29680 SIPP Module, 1MB 80ns 29690 32 .95 12.00 4.95 24.95 39.95 49.95 5.45 795.00 5.45 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 295.00 295.00 XT (8088) 10MHz System XT (8088) 31MHz System 286-12 (80286) System 286-12 (80286) VLSI System 286-12 (80286) NEAT System 286-20 (80286) 20MHz System 386SX (80386SX)16MHz System 386-33 (80386) 33MHz System I 895.00 1095.00 1225.00 1595.00 1695.00 2050.00 1995.00 4795.00 All systems are fully bullt and tested, with RAM fitted. Simply add the video card and monitor of your choice. 12 months warranty applies to all Board Solutions Systems. INTERNAL FLOPPY DISK DRIVES YE-Data 360K YE-Data, 720K/1.44M D3000 drive Plus Frame YE-Data, 1.2MB I. X1010 X1030 X2859 X2861 X2860 X2862 X3861 X3863 D5500 D3000 D301 O D5510 149.00 184.95 199.00 175.00 INTERNAL HARD DISK DRIVES NEC 42MB, 28mS 3.5in D8000 plus Frame M'scribe 40MB AT BUS 3.5in Kalok 20MB 40mS Seagate 20MB ?Oms RLL inc XT controller. Seagate 20MB 65ms RLL inc XT controller Seagate 30MB 65ms MFM incXT controller Seagate 40MB ?Oms MFM inc XT controller Seagate 5.25in 40MB 40ms RLL Seagate 5.25in 40MB 28ms RLL Seagate 5.25in 65MB 40ms RLL Seagate 5.25in 65MB 28ms RLL Seagate 42MB 24ms VIC I For Amiga 500, 1000, 2000, 3.5in 880K For Amiga 500, 1000, 2000, 5.25in 360/880K For Commodore PC1, 5.25in 360/720K 40/80 track For Atari.ST series, 3.5in 720K For Atari ST series, 5.25in 3601720K 40/80 track For Amstrad PC1512/1640 , 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT, 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB D9500 249.00 D9510 299.00 D9520 D9530 299.00 299.00 D9540 299.00 D9550 D9560 D9570 D9580 D9590 269.00 299.00 329.00 299.00 329.00 D9600 349.00 D9610 399.00 I. .._I____________ _. MICE & JOYSTICKS D8000 D8010 D8020 D8100 745.00 775.00 795.00 399.00 D8200 529.00 D8210 575.00 D8220 629.00 D8230 D8240 D8250 D8260 D8270 D8390 675.00 775.00 795.00 849.00 899.00 849.00 Joystick PC/XT/AT 3 Button Serial Mouse Mouse Mat J1000 J1030 J1040 34.95 69.95 7.50 I MONITORS Monitor, Monitor, Monitor, Monitor, Monitor, Monitor, I 14in TTL, Amber 14in TTL, Green 14in TTL, Paper White 14in EGA 14in VGA 14in Multisync M9000 M9010 M9020 M9030 M9040 M9050 249.00 249.00 249.00 599.00 749.00 ____.., 899.00 MICRO CHANNEL Dual Sync Adaptor, PS/2 2MB RAM Card, PS/2 OK RAM 8MB RAM Card, PS/2 OK RAM PHONE OR FAX NOW FOR LATEST PRODUCTS. PRICES AND INFORMATION OOPS! OVERSTOCKED ALL-IN-ONE "AT" MOTHERBOARD: SLASHED BY $100 - ONLY WHILE THEY LAST! J_Iere 's a sensational bargain - if you're quick! We're dramatically overstocked on these superb '286 motherboards which include serial and parallel ports and hard/floppy controller on board. Update your old XT snail to AT performance! Normally fantastic value at $545.00; Our ~uppli~rs have re~lly, because we're overstocked we've done It this t~me: th~y didn t slashed the price - only while stocks see the ~ec1mal pomt and last - by a massive $100.00 I MC1000 299.00 MC1010 349.00 MC1020 599.00 WHATA BOO-BOO! sent ten times our order. Our difficulty is your opportunity: YOU REAP THE BENEFIT! HURRY! THIS MONTH ONLY OR UNTIL CURRENT STOCKS SOLD! RAM CARDS I/O CARDS 2 Ser. 1 Parallel Games, Parallel & 2 x Serial Chip Set & Cable suit 11040 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive types supported (XT Only) Parallel Printer Card (XT/AT) Serial PortCard X 1 (XT/AT) Serial PortCard X 2 (XT/AT) 1/0 Plus Card - XT Only Serial/Parallel Card - XT/AT 2 Serial, 2 Parallel, AT Games, Par, Serial XT/AT Multi-Serial Card, 4P-AT I 74.95 99.95 29.95 129.00 i1010 i1020 i1030 i1040 i1050 i1060 i1070 i1080 i1090 164.95 29.95 54.95 69.00 99.00 64.95 84.95 89.00 245.00 VIDEO CARDS VGA Card, 800 x 600 (256K) VGA Card, 1024 x 768 (512K) Magic Combo CGA Card EGA Card Mono Hercules Card, 16MHz operation + Parallel Port I i1080 i1110 i1041 i1000 V1000 V1010 V1020 V1035 299.00 399.00 129.00 179.00 V1040 99.00 POWER SUPPLIES 200 Watt PSU Suit Tower Case 200 Watt PSU Suit Baby T Case 150W PSU, Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU, Baby AT, L Type 220W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap. 220nF/200V I P2020 P2030 P1500 P1510 P2000 P2010 P2200 P2040 P9000 195.00 149.00 85.00 124.00 149.00 149.00 195.00 695.00 3.95 KEYBOARDS 84 Key Keyboard XT/AT 101 Key Keyboard, XT/AT 101 Key Keyboard + TrackBall K1000 K1010 K1020 95.00 115.00 199.00 RAM Card, OK RAM, XT only 2MB RAM Cd, OK LIM/EEMS AT 2MB RAM Cd, OK LIM/EEMS XT 6MB RAM Card, -OK RAM 4MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 +33MHz R1000 R1010 R1020 R1030 R1040 R1050 INTERFACE CARDS 99.00 265.00 245.00 295.00 299.00 349.00 DISK CONTROLLER CARDS Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card - AT ESDI HDD/FDD Card - AT Hard Disk Cont, 1:1 lnt. 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(4 front, 2 rear) & 200W PSU Tower for 6 Devices, (6 front) Tower for 6 Devices, (6 front) + 200W PSU Case, hinged XT C1000 139.00 C1005 . 199.00 C1010 249.00 C1020 275.00 C1030 99.00 C1040 115.00 125.00 C1050 C1060 25.00 C1070 189.00 C1080 325.00 C1090 399.00 C1100 C1120 549.00 399.00 C1130 C1140 549.00 95.00 48 Line 1/0 Card F1130 Serial RS-422 Adaptor F1140 Industrial 1/0 Card F1150 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interface Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-D/D-A Converter, 12 brr, 1 Ch. F1080 A-D/D-A Converter, 12 brr, 2 Ch. 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PLEASE CALL ! • 14 Day money-back guarantee (except software) • At least 6 months warranty on all our products. • Mail orders are our speciality! • Road Freight on normal size items is $9.00 • Insurance $1.00 per $100 of order value • All prices INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call for latest price list • Special prices apply until September 31, or while stocks last! • Leasing facilities available: just ask! • Government pricing available on request BOARD SOLUTIONS IS YOUR ONE-STOP PC ENHANCEMENT COMPANY ~SH«d 4- 8OARO SOLUTIONS PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 r: 7 0 ◄ 0 w 2 :::J ...J 0 > C a: Zo ::::, 1- ,... 0 c::c 0 Cl) ..J O') O') LL ::::, 0 ,... a:~ CX) ::::, 0 - Cl) i(/) 0 Cl) a: w 3:: 0 0 Q. __J JI r 1un11 7 OFF 12V DC IN POWER ON Fig.4: here are actualsize artworks for the PC board & the front & rear panels. AUDIO OUTPUT _J L can just squeeze the socket in. Be very careful not to make this hole too big, otherwise you won't be able to install the mounting screws. The holes for the mounting screws will have to be countersunk slightly so that their threads protrude through the socket body. In order to install the internal speaker, you need to remove the centre mounting pillars from the lid 32 _J SILICON CHIP of the case. This can be done by using a large drill bit running at low speed. Too fast a speed causes the plastic to break and spin off in all directions. The only ones to leave are those adjacent to the sides of the case [see photograph]. Once this is completed, you need to drill a series of large holes in the lid for the sound to escape. The speaker is secured to the top of the box using four clamps. We made ours from scraps of 20 gauge aluminium and bent them slightly with a pair of pliers. Once they are screwed down, they provide a secure grip and prevent the speaker from slipping around. Finally, install the pot, the LED bezel and the remaining components and wire them up to the board, as shown in Fig.3. Run the wiring using light-duty hookup wire and take care with the connections to the LED. Testing If you're sure that everything is correct, you can now connect the 12V plugpack. Make sure that "positive" is the centre pin of the socket and the inside of the plugpack plug. If you measure the voltage of the plugpack, it should be about 16.5V volts, with ground on the outside of the plug. Next, switch on and turn up the volume. You should hear the roar of that first big wave crashing onto the beach and slowly flowing back into the sea. If not, check the output of the 7812 regulator IC and the supply pins of the ICs. They should all be at exactly 12V. If the supply voltage is correct and the circuit still won't work, switch off and check the circuit board for solder .splashes, missed solder joints and incorrect parts placement. If you have a CRO, use it to check that the triangle wave The rear panel of the SurfSound Simulator carries a DC power socket, a power ON/OFF switch and an RCA audio output socket. You will have to countersink the mounting holes for the DC power socket slightly so that the screws pass through the socket body inside the case. generators are operating correctly (pins 7 & 14 of IClb}. Also, check the outputs of IC2a & IC2d. The only control in the circuit that needs adjusting is the volume control. Depending upon its position, you can make it sound like a ANTRIM TOROIDAL TRANSFORMERS QUALITY TOROIDAL POWER TRANSFORMERS, MANUFACTURED IN U.K. NOW AVA ILABLE EX-STOCK AT REALISTIC PRICES. sheltered beach in the middle of summer or a raging storm in the middle of winter. Whichever you prefer , the SurfSound should provide you with hours of listening pleasure or at the very least a decent night's sleep! E-1 LAMINATED POWER TRANSFORMERS PCB MOUNT STOCK RANGE PCB mount ex-stock in sizes from 2.5VA to 25VA with secondary voltages from 2 x 6V to 2 x 20V. Triple output models also available for logic circuits. Chassis mount man ufact ured to order in si zes from 2.5VA to 1 KVA in E-1 and C core. CHASSIS MOUNT TO ORDER We are the largest ex-stock supplier of toroidal power transformers in Australia. Our standard range consists of the U.K. manufactured ANTRIM range in 10 VA sizes from 15VA to 625VA. All have a single 240V primary and dual secondary windings ranging from 2 x 6V to 2 x 55V. Our local manufacturing facilities supplement this range by manufacturing specials to order. Models are available from stock to suit most project kits. Comprehensive data sheets are available on request. Enquiries from resellers and manufacturers are welcomed. Prices are extremely competitive and generous trade discounts apply for quantity. HARBUCH ELECTRONICS PTY LTD 90 George St., HORNSBY NSW 2077 Phone (02)476-5854 OCT0BER1990 33