CFL energy savings non-existent

With regard to your article on the proposed ban on incandescent lamps (April 2007), the purpose is to save energy, right? Maybe our politicians ought to take a step back and look at the bigger picture.

The cost of a product often relates reasonably well to the energy cost of mining and refining the raw material, manufacturing, packaging and transport. So a CFL might cost say 10 times the (energy) cost of an equivalent incandescent to supply to the customer.

I have quite a number of lamps in my house that are essential but are infrequently used and then only for very short periods of time. I’ve yet to see a 500W CFL flood lamp and would hate to think of the cost – yet my rear security light is just that and would operate for perhaps 90 seconds per year!

The point I am making is that putting CFLs in these locations will certainly result in a net whole-of-life energy loss. That is, the power station will have to produce more power to make and run these CFL lamps, over a lifetime, than the incandescents they replace. Obviously, this argument does not apply to high-use lamps and I support their application. But in my considerable experience, the life of CFLs can more typically be around the 300-2000 hour mark and this seriously impacts the energy benefits of their use. Perhaps the pollies need to employ engineers to add some logic and sense to their pontifications.

Ian Thompson,

Duncraig, WA.

SILICON CHIP: the last of the Mohicans Firstly, congratulations on the outcome of your first excellence awards, announced in the February 2007 issue. It is really hoped that this initiative continues to grow. Remember that if even one student is motivated you have succeeded. Perhaps I could be described as a "magazine junkie", having started in my school days with Radio & Hobbies and moving on to such publications as Electronics World, Electronics Australia, ETI, CQ, QST, 73, Talking Electronics, Nuts and Volts, Practical Wireless, Amateur Radio and from its first issue, SILICON CHIP. No doubt you have visited a newsagency recently and have observed that you are just about the last of the Mohicans. We all have pet theories as to the mechanisms driving the demise of some of these publications and I see the deliberate "dumbing down" of the country right at the top of my list. In the midst of all of this, SILICON CHIP has continued to go from strength to strength, so please take a pat on the back, as my perception is that it is serving a wider interest base. In his comments on the publication of articles on valve amplifiers (Mailbag, page 9, February 2007), Ian Farquar is certainly on the wrong tram. In the world of hobby electronics, experimentation is a positive way forward and valve technology, albeit becoming obsolescent, is a valid hobby interest. While comparisons between valve and solid-state technology may be valuable, discussions as to which is "better" are meaningless. Any "hands-on" experience gain-ed through construction will provide educational benefits well beyond the use of commercially-built equipment or computer simulation. It must be said that the current wave of TV advertisements promoting apprenticeships and encouraging students to turn to maths and science raise doubts in regard to the motivation behind them. With the anti-science campaign of recent years being so well organised and funded, and indeed being very successful, I wonder how it will be possible to put the knitting back together. For example, how could a student cope with university level studies in maths and science-oriented subjects after passing through a school system where the teachers of these subjects are on the endangered species list? George McLeod, via email.

23W energy saver lamp flashes at night

I would like to bring an interesting side effect of CFLs to your attention. I bought two 23-watt "Philips Tornado", "Compact High Light Output", "Energy Saver" light bulbs from Coles in Sydney. The packaging states that they "can operate within 170-250V range".

These bulbs are very bright (equivalent to 125W incandescent) and give off a fairly pleasant warm white light. The interesting (and slightly irritating) bit is that when mounted in a ceiling light and with the wall switch turned off, the lamp dimly flashes very briefly several times a minute, all night!

I tested each of the bulbs in various ceiling fittings, finding the flash rate varies slightly, depending on location. Neither bulb would flash in a lamp that breaks both Neutral and Active. I could not reproduce the effect in several other types of "energy saver" lamps that I have at hand.

The light circuit wiring and switches in our house is old and possibly a bit leaky. The switch is definitely in the "Active" line. An old DMM shows either zero or 1-2V AC across the open circuit socket with the light switch off.

I assume that there must be some fairly efficient (non-leaky) electronics in the bulbs to produce this effect. The only device, to my knowledge, of similar efficiency is a neon indicator that has sufficiently high impedance to flicker in this sort of situation.

Lee Braithwaite,

via email.

Comment: we recently observed the flashing CFL effect ourselves in a number of lamp fittings. We have concluded that it is not a fault in the CFL or the 240VAC wiring but an artefact of the capacitance of the wiring to the light switch (from the ceiling junction box). In a typical home, this will be about six to eight metres of sheathed twin cable and this can be expected to have a capacitance of maybe 300pF or more.

In effect, this cable capacitance across the switch lets the CFL bridge rectifier build up sufficient DC to let the circuit fire the CFL tube, collapsing the DC and letting the cycle repeat ad infinitum. It is acting as a relaxation oscillator.

While you are aware of the flashing effect only at night, it happens all the time. If it worries you, it could be stopped by connecting a small capacitor across the CFL socket, say .01mF (10nF) 250VAC class X2. Alternatively, the effect could probably be stopped if the cable to the switch was changed to "twin and earth".

This leakage capacitance effect also occurs with incandescent lamps (and any other load for that matter) but it is of academic interest only.

Playmaster AM/FM tuner morphed into mailbox Almost the whole nation is awash with idiotic-sized tiny letterboxes which were designed for the needs of the 1920s. There must be millions of (A4-size) magazines which are subscribed to in Australia every year but when they arrive at the average home, we see the mail-person fold it in half and squeeze it (and any attached CD or DVD) through the tiny slot of the letterbox. My personal solution to the problem is the new Playmaster Snailmail Inbox project. It is the perfect size for A4 magazines and is based on the Playmaster Stereo FM Tuner-Digital Clock project by Leo Simpson in the November & December 1978 and January 1979 issues of "Electronics Australia" magazine. I also plan to have a 150mm diameter newspaper tube suspended underneath it. Michael Katalinic, Lavington, NSW. Comment: what sacrilege! Your old AM/FM tuner project should be venerated in a softly lit display case in your home rather than having to stand out in the elements and being force-fed junk mail. We are very sad at this sorry state of affairs. Seriously, you are right. But rather than recycle defenceless tuners, there are millions of old computer cases which would be suitable for the job. Painted and adorned with a street number, they should last many years.

GPS frequency reference is not optimum

I would have expected a more reliable design than that used for the GPS-Based Frequency Reference in the March 2007 issue. The method used to cascade counters IC4 & IC5 is incorrect.

The TC output of a 74HC160 synchronous counter is not guaranteed to be glitch-free and the following counter can increment on glitches in TC. The correct method would have been to cascade the two 74HC160s and the following JK flipflop synchronously, by connecting the TC from IC4 to CEP of IC5, and connecting TC from IC5 to the JK inputs of both flipflops in IC6. IC4, IC5 & IC6 should then be clocked from the same 10MHz source.

The easiest fix to the circuit error is to connect pin 11 of IC4 to pin 11 of IC3e, connect pin 11 of IC5 to pins 14, 3, 7 & 10 of IC5 and connect pins 1 & 5 of IC6 to pin 2 of IC5.

The phase of the 50kHz signal relative to the 1MHz signal is unimportant so this fix will work well. The design will then work reliably over time and temperature even if different man-
ufacturers’ parts are substituted. Not all 74HC160s are equivalent in performance.

If instead of connecting the outputs of IC8 & IC9 to the 8-bit DAC register (IC12), the phase measurements had been filtered with a Kalman filter in the processor and then the resultant high resolution averaged data fed to the 8-bit DAC via a software dither generator to increase the effective DAC resolution, far higher accuracy and stability would have been achieved.

In fact the 4046 and associated dividers could have been eliminated by clocking IC8 + IC9 continuously by the 10MHz oscillator being disciplined and sampling the current count on the leading edge of the PPS signal. About 100ns RMS random jitter would need to be added to the PPS signal to ensure unbiased averaging of the phase samples. A synchroniser (8-bit shift register) would be used to synchronise the jittered PPS signal to the 10MHz oscillator being disciplined. A 74AC164 or equivalent performance device would be required to reduce the rate of synchroniser failure due to metastability to less than once in a few billion years. HCMOS is way too slow for a synchroniser.

The second 10MHz oscillator is thereby also eliminated. The short-term stability of the 10MHz oscillator could be significantly improved by using a relatively simple discrete bipolar oscillator rather than a noisy gate oscillator. It should then not be too difficult to achieve a short and long-term stability of better than a few parts in a billion.

Dr Bruce Griffiths,

Hamilton, NZ.

Comment: see the amended GPS-Based Frequency Reference circuit in this issue.

Dumped computers have intact records

Here are some ideas for recycling. When I buy a drum pack of CDs there are spacer washers included on each side of the stack to keep the CDs from self-destructing in transit. These are perfectly sized for hose to tap washers on your garden hose.

With the advent of reasonably priced "direct to CD" printers, the imagination runs wild on all the possible designs for clock faces that could be printed on a CD (at less than 30c). For $5 or less you can get a quartz clock movement from craft or $2 shops that fit extremely well in the hole of the CD. It makes a nice, original, useful, cheap gift.

CD-ROM drives can be used (with a redundant power supply) as a stand-alone CD player. The analog output is directly compatible with any consumer amplifier line RCA inputs, so all you need to do is make up a lead with the right plugs. However, when selecting a CD-ROM, check the front panel buttons and make sure it has a dedicated play/skip button in addition to the eject button, so it can be manually operated; some drives don’t have this feature. Obviously, to keep it simple, there is no software control and it could be mounted in a box with an environmentally friendly off switch.

On a more serious note, computers from my local tip/recycling centre/waste management facility now include DDR P4s, in addition to the odd $10,000 industrial colour laser (HP8550DN, HP4500DN), mono lasers (HP4050DN by the score), plotters (HP650C, HP755CM) and photocopiers, sometimes with absolutely nothing wrong with them other than crash damage from being toppled out of a ute/truck.

However, my concern is the boxes that, for whatever reason, have become superfluous to present needs and end up on the heap. Some computers do have minor faults (maybe a dirty connection, blown video card, modem or power supply, or the RAM needs reseating) but they often come with the entire hard drive intact, just waiting to be removed and re-sited in my test rig for perusal.

I have come across computers from a government hospital with full patient records, from an accountant with every-one and their stuff that he’s worked for since 1993, a solicitor with 36,000 individual clients, what they own, where it is, how much it’s worth, etc, defence department machines with names & addresses of generals and other senior ranks, schools with personal child details, small businesses and all their affairs, plus aid agencies (both domestic and international).

I’m no wizard, so if I can access this then what do the dedicated detectives see when they go looking? By bringing this up I’m probably shooting myself in the foot and I’ll have to start collecting garbage bags and food scraps ‘cause there won’t be any more hardware. But I will be able to sleep soundly knowing that I’ve done the altruistic bit this year. Any other readers got similar horror stories?

Name and address supplied but

withheld at the writer’s request.

Comment: you would think that any government department or business would at least security wipe any drives before dumping computers. Better still, they should pull out the drive and destroy it, to prevent data recovery.

Modern cars have
too much performance

With respect to Julian Edgar’s scathing article on fuel economy, etc of modern cars (SILICON CHIP, December 2006), I fully concur with everything he said but he should have said more.

In the mid 1970s when the fuel crisis had become reality, I remember an article quoting vehicle manufacturers’ predictions whereby in the 1990s we would have cars that would achieve 3 litres/100km. This could be one of those false memories that some of us suffer from time to time but there is no doubt in my mind it could have been achieved.

Julian blames weight, which is a big factor. I blame the power-to-weight factor. Many modern cars would have been racing cars in the 1960s and 1970s. Recently, the Topgear TV show put two muscle cars from the 1960s, a Jaguar E-type & an Aston Martin DB4, against a Honda Accord Euro (2.4l). The Honda murdered the oldies in every test.

How much better would fuel economy now be if we stayed with the same performance levels as average cars of the 1970s?

John Taylor,

Donvale, Vic.

Ferocious Felines Fouling Flivver’s Fine Paint Finish

In reference to your correspondent’s problem with cats scratching the paint of his/her new car (Ask SILICON CHIP, February 2007), a friend has the same problem and solves it effectively by putting mothballs in a stocking and leaving the bag on the bonnet of his car. The cats soon got the message.

Keith Gooley,

Adelaide, SA.

Priority switching

for CB radio

I am writing in response to the request by T. D. (Ask SILICON CHIP, March 2007) regarding a mixer for CB and/or mobile signals through his car sound system. This system was used in the 23-channel "Clarion JC-201E" CB radio, using the "RCJ-001" remote control head. This operated a relay to switch both stereo channels from the stereo system, the right channel being silenced and the CB output being fed to the left channel.

The remote head in this case also housed the channel selector but this had no role in the audio switching, the incoming audio providing the drive signal to the switching transistor to operate the relay. The audio was controlled by the "Squelch" control, hence only a user-selectable level of audio was applied to the system. This ensured reliable operation and avoiding undesired interference to the stereo sound.

Don Henriks,

Adelaide, SA.