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Here’s a project ANYONE can build . . . 4-Minute Shower Timer With most of Australia still gripped by drought (ie, save water you lot!) and energy costs steadily increasing (ie, save hot water you lot!) every little bit helps. Here’s a timer that will automatically prompt (shame?) you into taking shorter showers! Words by Ross Tester 60  Silicon Chip siliconchip.com.au New VAF speakers not just for audio perfectionists VAF Speakers have a legendary reputation for providing the best accuracy and value. They are also available as kits because we know that’s the way enthusiasts like them. VAF’s brand new Generation 4 DC-Series is now available and offers extreme levels of accuracy at incredible prices. They go very deep so they can be used for Home Theatre without a subwoofer in many rooms. They are very sensitive so they don’t need big expensive amps to drive them. They can take high power so if you have a huge room or simply want to play loud, you can. They also work well close to walls so you can use them in small rooms too. G one are the days when we can afford to luxuriate under a hot shower for hours on end. Well, maybe the showers weren’t quite that long but most people are used to taking showers in the tens of minutes. It’s easy to lose track of time in the shower. And it does feel nice. That’s a luxury that’s no longer economically nor ecologically sustainable. First of all, we’re short of water. In most areas of Australia the powersthat-be keep telling us if we don’t be good boys and girls and cut our water usage then we are going to run out. (Those same powers [read politicians] that keep blaming us wasteful consumers don’t mention that for the most part water shortages are their fault, because they haven’t invested the necessary dollars in water infrastructure while population has steadily increased for much of the last half century. But let’s not get into that argument. At least not right now . . .) Second, we’re short of electric power. The power that goes to heat the water is also in very short supsiliconchip.com.au ply. Load shedding (ie, blackouts!) is becoming more and more common as supply authorities attempt to cut peak loads. Those same powers-that-be keep telling us that if we don’t reduce our consumption of power, it’s going to get worse. (Those same powers [read politicians] that keep blaming us wasteful consumers, etc etc etc . . .) Putting aside all the scare-mongering that’s going on in political circles (my spell checker wanted to change that to circuses, which would be perhaps more apt) it really does make sense for us, as consumers, to try to save both water and power – if only because that means less of our hard-earned dollars will end up in Government coffers. One way to do both, of course, is to take shorter showers. How short? VAF Speakers are used by the ABC, Parliament House in Canberra, and in preparation of many international DVD titles in Australia.... You can use them too. Buy direct from the people who make them, and for less than you may think. 4 new kits from $449pr to $1,999pr. If you want instant results, fully assembled versions are also available. For Info or to Order FreeCall 1 8 0 0 8 1 8 8 8 2 email vaf<at>vaf.com.au www.vaf.com.au The 4-minute shower Believe it or not, it is entirely possible to take a shower in four minutes – including, if you need to, washing your hair. In fact, without shampooing, January 2005  61 Parts list – Shower timer 1 pre-assembled PC board 1 2-part plastic case 1 self-adhesive foam “donut” 1 self-adhesive foam rectangle 2 suction caps 1 9V battery (preferably alkaline) The PC board is supplied completed and tested – just as well, because soldering those surface-mount devices can be a pain! The white object at the right side is the foam gasket which virtually covers the piezo transducer. a sub-three-minute shower is perfectly practical. People in the bush who don’t have the luxury of hot water have been “getting” that sort of shower for years: get in, get wet, get clean, get out! Let’s face it – all you really need to do is get wet, soap up and rinse off. Get wet: 30 seconds. Soap up: 60 seconds. Rinse off: 60 seconds. That’s two and a half minutes. Add another 60 seconds to shampoo your hair and there’s your four minute shower – with 30 seconds left over for good measure. OK, if you agree that four minutes is enough time, how do you go about convincing everyone in your family? The ST4 Shower Timer This rather ingenious (and patented) design is completely automatic, turning on about 20-30 seconds after it “hears” the first “sssshhh” of the shower – giving you enough time to adjust the water temperature – then beeping each minute up to the magic four minutes, at which time it sounds an alarm. The alarm stops when you turn the shower off. But if you try to fool it by turning the shower off for a moment and then back on again, the alarm will start back up again. It resets after about a minute of no-shower-sound, ready for the next person to take their shower. Part of the secret to this circuit is the use of the piezo buzzer: it is not only sounds the beep/alarm, as you would expect but it is also used as a “microphone” to pick up the splash sound. There’s no on-off switch; it simply operates when it hears the shower turn on (listening for the distinctive splashing sounds of the water). There is an internal 3-position switch and preset pot which are adjusted to give the desired sensitivity – once set, you can forget it. There are also pots to control clock frequency and tone of alarm – but these are set in the factory and should not need touching. It’s operated by a 9V battery (alkaline preferred) which should last for at least 12 months. Current drain, when ready to operate but inactive, is comparable to that of a smoke detector – around 10-15mA. The circuit, including the piezo, is housed on a single PC board which fits (along with the 9V battery) into a purpose-designed two-part case. When correctly assembled is quite waterproof. Mounted on the shower wall it allows shower sound to enter and beeps/alarm to escape without the circuit getting at all damp. The case, as we said, is in two parts. These snap together to form a nice, tight seal around the PC board, with alignment of the two parts taken care of by pins and holes which mate. Each half of the case is fitted with a suction cap which allows the unit to mount to any smooth shower wall (or even a glass screen). While the ST4 Shower Timer is available fully built and tested, we are more interested in it as a kit which you assemble yourself. Even here, most of the hard work And here’s how it slots together. The piezo transducer (with its gasket) is right down in the bottom of the case, with the PC board slotted into the guides. The top half of the case has two pins which mate with the moulding on the bottom. Note that we have not yet fitted the suction cap to the top half of the case so that you can see where it slides into place. 62  Silicon Chip siliconchip.com.au siliconchip.com.au January 2005  63 CLOCK FREQ. VR1 100k 680k 220nF SC 2005 TP5 TP4 TP3 8 Vss 34Hz Ctc Rtc O9 O11 O12 O13 15 1 2 3 IC2d 12 13 220nF 7 5 4 6 14 1.5 – 2.2 µF 11 12 MR O3 O4 O5 O6 O7 IC4 13 O8 4060B Vdd 16 SHOWER TIMER 9 10 Rs 680k 11 NOTE: TP1 – TP2 AND TP4 – TP5 ARE LINKED AFTER PRODUCTION TESTING TP2 TP1 47nF 240k IC1 PIN14 TP11 +3V IC2a 4 3 13 10M 6 5 A TP7 10 IC2b 14 4 7 IC2c +9V 5 8 9 TP6 IC3c 470k 6 33k K A 4.7M Q1 BC849C TP8 E C D1 BAS16 B 7 IC5b 10M 2 8 220nF 1 4.7M 4.7M 1nF +9V 9 TP9 5 TP13 6 7 IC1b 10M 10M 6 5 TONE FREQ IC5a 680k 4 3 14 TP14 2 1 1nF A 2 BAS16 A6 IC3f 390pF 13 K S1 SPLASH SOUND SENSITIVITY TP10 IC1a 1nF 240k VR2 100k 1 IC3a 12 2.2k IC1, IC3: 4069UB IC2: 4093B IC5: 4023B IC3e 68k 33k 33k 14 B 7 IC3d VR3 100k 9 11 E 2C C PIEZO SENSOR/ BUZZER BC849C 8 10 The piezo transducer (far right side of circuit) has a dual role of both sensor and alarm, with IC1a, b and Q1 amplifying the signal picked up. The rest of the circuit mainly consists of timers to set up the various alarm periods plus oscillators to make the noise. IC3d, e and f form an amplifier to drive the piezo transducer. 10M K 10 TP15 220nF IC5c D2 BAS16 START BEEP MODULATOR 2 1 4.7M 3 IC3b 11 12 220nF +9V Turn the radio on and the timer should give a chirping sound after 20-30 seconds (that’s the water temperature adjustment period). Then it should beep after each minute from there, with a series of beeps (7.5 seconds on, 7.5 seconds off) at the end of four minutes. Turn the radio off and the timer should reset. Mounting in the shower Here’s how to identify the top and bottom of the case. The bottom is facing towards the camera with the slots for the piezo transducer clearly seen. Again, the suction cap has not yet been fitted to the top section. – soldering the surface-mount components and ICs – is already done for you. In fact, as supplied, the PC board is built and tested, ready for you to put together Putting it together Assembly is as simple as removing the backing and the centre from the self-adhesive “donut” foam ring and sticking it, as central as possible, onto the piezo transducer. Then similarly stick the rectangular foam pad onto the back of the PC board (it keeps the battery snug while preventing it shorting to or across the board), then push the PC board into the bottom half of the case. The bottom half can be identified by the slots for the transducer. When the board is pushed fully home, the foam donut “gasket” provides a seal in a moulded housing inside the case, preventing any water entering the case – theoretically even if dunked. We say theoretically because it is designed that way – but commonsense would suggest you don’t try to prove it. Because the transducer slots are at the bottom of the case, spray would have to be travelling upwards to enter – possible, of course. But the foam donut stops this water going any further. While the transducer itself is not sealed, its internal construction means that it is also an effective water barrier, so with the sealing donut in place, spray cannot enter 64  Silicon Chip the case nor either around or through the transducer. All this means that the shower timer is for all intents and purposes waterproof, especially from spray. Once the PC board has been pushed home, the battery can be connected and slid down into the case, alongside the (now insulated) back of the PC board. It should be a relatively snug fit. In the unlikely event that the suction caps have come off the case halves in transit, simply slide them back into their respective slots on each end – the photos show where they go. Slide the two halves of the case together, ensuring that the channels which hold the suction caps line up exactly – the pins in one half won’t mate if they don’t. The two case halves should “snap” together and that completes construction. Testing If you don’t want to get wet, you can use a small unmuted FM radio, off-station, to simulate the sound of a shower. (If your FM radio mutes automatically, or the mute cannot be turned off, this option won’t work. You’ll need to check it in situ – in the shower!) The FM radio will produce predominantly white noise, which is fairly close to the sound of a shower stream striking the bottom of the shower or bath. The timer always mounts vertically, with the piezo transducer towards the bottom. The suction caps should stick very well to any ceramic tile, glass or other smooth surface – if necessary, give ’em a lick first! Best position for the timer is about 300-400mm from the floor but it should work reasonably well up to about waist height. If you need to mount the unit higher than this, or if it doesn’t appear to be sensitive enough, open it up and slide the switch up one notch. Don’t mount any higher than necessary. In some very low volume showers, (eg some gravity feeds), you might need to adjust the sensitivity right up but this would normally be unlikely. You should not need to adjust any of the pots – they are preset on factory assembly. Once mounted, give it another run, this time with the shower. It should perform in the same way as it did in your “white noise” test. The only time you should need to remove the unit from the wall is to replace the battery and this could be up to a couple of years or so! Don’t pull on the timer to remove it, slide a knife or some other thin, flat object under the suction caps to break the seal. SC Where from, how much? The TD4 Shower Timer is available from Gum Leaf Energy Saving Systems Pty Ltd, 26 Park St, Seaford, Vic 3198. Tel/Fax (03) 9776 8703; email glesstron<at>msn.com The kit price (with pre-assembled and tested PC board) is $24.50 plus p&p, while a fully built and tested version is $35.00. Pack and post, for up to four units, is $6.90. The battery is not included with either kit. siliconchip.com.au