Incandescent bulbs cause more mercury pollution than CFLs

I found this interesting document that claims that incandescent bulbs are responsible for more mercury than CFLs. It was in a US Environmental Protection Agency fact sheet at: www.nema.org/lamprecycle/epafactsheet-cfl.pdf

"Ironically, CFLs present an opportunity to prevent mercury from entering our air, where it most affects our health. The highest source of mercury in our air comes from burning fossil fuels such as coal, the most common fuel used in the US to produce electricity. A CFL uses 75% less energy than an incandescent light bulb and lasts at least six times longer. A power plant will emit 10mg of mercury to produce the electricity to run an incandescent bulb compared to only 2.4mg of mercury to run a CFL for the same time".

Franc Zabkar,
Barrack Heights, NSW.

Comment: we think the US EPA is drawing a pretty long bow by referring to mercury pollution via coal burning emissions. In any case, as inferred in the Publishers’ Letter in the April 2007 issue, we do not think the banning of CFLs will result in much reduction, if any, of carbon (and related) emissions.

CFL article
was alarmist

I was interested to read your article on CFLs in the April l2007 issue. I am running on solar power and have used CFLs virtually exclusively for about 12 years so I can make a few comments.

I think your article is a bit alarmist. First of all, the life of CFLs is highly variable. Some of mine have lasted in excess of 12 years and I have only replaced one or two because of decreased output. Almost all replacements have been from sudden failure, usually without warning, at switch on. One failed explosively; apparently a capacitor in the works. I have had no problems with using CFLs in sealed fittings – all my outside lights for example are in 7-inch spheres.

While the RFI from CFLs can be heard by tuning off-station on the AM or SW bands and moving the radio close to a bulb, it is less than the hash from the main inverters supplying the house and markedly less than the interference from my PC. I have never encountered any remote control problems that could be attributed to them.

As far as vibration goes, I have been using them in lead lamps in the workshop for years, one of their main advantages being they don’t fail if you bump or drop them.

Your display of CFLs for comparison with incandescent lamps is clearly prejudiced – for a start, all the ones shown would have to be described as obsolescent types. The base containing the electronics today is typically half the size of that portrayed – 42 x 27mm compared to 50 x 45mm (measured from ones to hand). The variety of types in your supermarket is already much greater than the ones you show – the ones in my pantry include reflector globes, "candle" types and "Decor" spherical bulbs.

Bases available include all the ones shown in your display of incandescent bulbs except the low-voltage halogen. The form factor of CFLs today can be pretty much the same as ordinary incandescent bulbs, as can the light distribution.

The mercury problem exists as you suggest but it is hardly going to be much worse than the mercury from the millions of conventional fluorescent tubes already in use. One of the points you do touch on is that replacing incandescents in air-conditioned premises has a double value; it reduces the energy costs for air-conditioning as well as lighting.

One point you do not mention – as far as I can work out, CFLs typically have a power factor of about 0.5 compared with a PF of 1.0 for incandescents. I am not sure what effect this will have on power distribution networks but with large-scale substitution it may become significant.

Finally, I have to agree that replacing incandescent lights is not a major step in energy savings, although if the figures given by Malcolm Turnbull are correct, then households should be able to make a reduction of about 5% or more in energy consumption. As noted above, since commercial lighting is already overwhelmingly fluorescent, the savings in commercial lighting will probably be less significant.

As a final note in the context of global warming, Australia contributes around 1.4% of total man-made CO₂ emissions to the atmosphere – any changes made here will have an insignificant effect.

John Denham,
Elong Elong, NSW.

Comment: the CFLs shown in the article were all obtained within the last nine months. A CFL used in the bathroom of our premises here and installed a few months ago is already seriously blackened at the ends. Temperature rise in poorly ventilated lamp fittings is a serious issue. Most CFLs will have a very short life once their local ambient temperature exceeds 60°C.

We did not mention power factor because we erroneously thought that this was no longer a problem in more recent CFLs. This is quite wrong and it can be a serious problem if large numbers of CFLs are used on one phase of the 240VAC mains supply.

CFLs should work OK in lead lamps; it is continuous vibration that is the problem, whereby internal components are vibrated off their leads.

Dimmable CFLs made by GE are now available from Bunnings and other retail outlets.

More on
Edison recordings

"Give ‘em A Spin" was an excellent article on the history of recorded sound, in the May & June issues. However I doubt the claim that 4-minute cylinders sounded better than disks of that period. They all sounded rather dismal due to insufficient-sized horns of the wrong shape and limited recording frequency.

Edison utilised the "hill and dale" or vertical method of modulating his recordings, for both cylinder and later diamond disk records. Edison had to employ this method to avoid patent infringement of the Berliner camp. This had the advantage of louder modulation, because you only cut deeper into the recording wax. With the lateral system of recording, they had to be careful not to record too loud, lest they break down the record groove.

Edison’s diamond disk recordings of the post-WW1 period had better sound than most flat lateral recordings. In 1925, when electrical recording became available, sound quality improved greatly. The Edison Company utilised electrical recording on their late diamond disk recordings from 1927. Their quality is very good.

From this period, they also developed long play recordings. They were perhaps 30 years ahead of their time – because they were played back mechanically, groove breakdown occurred due to the rather heavy mechanical diamond disk reproducer. If Edison had decided to play them electrically, as was possible at that time, maybe history would have had a different turn. They produced 10-inch and 12-inch LP records that played for 20 minutes and 40 minutes in 1927.

Incidentally, the RCA Victor open horn phonograph shown on page 20 the May issue is a fake. These machines turn up all over Australia and are referred to as "Indian Phonographs". Genuine open horn Victors of this period utilise an "exhibition" type mica soundbox, not the type shown on page 20, and the horn has a tapering elbow where the horn connects to the soundbox tonearm. The one shown has a "mitred" joint which is typical of all fake machines.

Don’t be fooled by the fake HMV logo; at least they got that right. A lot of these reproduction open horn machines are manufactured from portable gramophone parts of a much later period.

Brian Lackie,
Urunga, NSW.

Delay timer for
sensor lights

With respect to the problem of movement-sensor lights staying on due to intermittent power glitches (Ask SILICON CHIP, page 97, May 2007), the best answer is to install a standard on-delay timer with 240VAC operating voltage, set to about five seconds delay. The timer will drop out on any power glitch and not come on again until the power has been steady for the delay period. These are available at any of the electrical trade supply places. The inbuilt relay in the timer will handle the rating of the light.

Mount it in a waterproof Clipsal plastic box, along with a light switch either on the box or in a convenient spot connected to the light side of the timer circuit to switch the light on permanently when required.

Please note that as this will almost certainly constitute "permanent wiring", it should be done by a licensed tradesman.

Rod Crimps,
Parkdale, Vic.

Incandescent lamp ban has unforeseen repercussions

Your article questioning the banning of incandescent globes in the April 2007 issue no doubt created great interest. I’d like to see a politician replace a fluoro light globe under our second storey eaves. It’s rarely used but highly useful from time to time. Fortunately, the incandescent survived 15 years before we needed to purchase a pole and "globe-grabber" to change it.

On the other hand, when an interior night light lamp recently blew, we replaced the 7W "fossil-fuel guzz-ler" with a 0.5W LED type. The light output is quite sufficient, though the lumens are most likely less than its predecessor.

A politician trolling for votes just mailed a list of pointers to people in our area, extolling energy saving ideas. The tips included "turn off appliances at the power point". Energy and resources were expended producing the glossy card and no doubt old people will now turn off toasters and other appliances that don’t have residual current!

Of more concern is the loss of programming and even damage when some devices are turned off at the wall. Turning off a cordless telephone while away for say, two weeks, will ruin the battery, costing money and landfill replacing it. Plus there is the cost, inconvenience and greenhouse gases emitted as people travel in their car to purchase a new one.

The same applies to VCRs. And when a computer’s parameter RAM (PRAM) backup battery (as found in certain Mac computers) fails due to no charging current for extended times, all the settings you perfected through dozens of decisions are lost; settings like mouse tracking speed, date and time, screen resolution, network and screen depth.

Unfortunately, this misguided switch-off advice can also result in a computer with a blank screen, totally unable to start, requiring a trip to the service department to restore it. Of course there’s also the equally high cost of this remedy, emissions from the transport (probably two trips) and landfill too.

Politicians and do-gooders should learn all the repercussions and have a healthy debate with technicians before imposing "pie in the sky" laws and ideas on the public.

Kevin Poulter,
Dingley, Vic.

Digital panel meter
assembly problems

I offer the following comments as a result of having built the Panel Meter project from the March 2007 issue.

I bought all parts exactly as per the parts list on page 77. The two Oatley Electronics DPM1 digital panel meters were supplied as 200mV FSD devices, not 0-20V as stated in the article. This meant that the setting-up and calibration of each meter was much more difficult. The descriptions and instructions provided by SILICON CHIP, Oatley Electronics and the DPM manufacturer were oversimplified and incomplete and a lot of experimentation had to be done in order to get the project working.

The brief slip of paper included with each DPM is intended to give instructions on how to add resistors to the DPM PC board so as to make "multipliers" or voltage dividers to convert the DPM from 200mV FSD to the desired value, in this case 20V or 20A. There are also instructions on how to set jumpers to control the decimal point position.

For a maximum voltage of 20V, we are told to "Disconnect wire jumper in R_B, R_A = 100 K, R_B = 9.9 M". But the "wire jumper" is in fact a zero-ohms surface-mounted resistor soldered to the PC board and I spent quite a lot of time looking for the wire jumper. Unsoldering the SMD was easy once the penny dropped.

Next came the search for a 9.9MW resistor with 1% or better tolerance – of course, they are unobtainable from normal sources. After much head scratching, I decided that this was only a multiplier after all, and the input impedance doesn’t really have to be 10MW for a 20V meter and about 2MW would be more than adequate. A little elementary arithmetic shows that for a multiplier ratio of 100:1, R_A has to be equal to R_B/99.

I decided to use all 1% resistors from Jaycar. R_B would be made from the series combination of 1MW and 820kW, and R_A from 18kW and 390W resistors, all 1% tolerance. Unfortunately this was not good enough, because the actual values of the various resistors were too far away from their nominal values.

I ended up selecting individual resistors from the pack of eight of each size, eventually reaching a compromise that gave a real-life multiplier ratio of 100.1:1. In each case (R_A, R_B), two resistors in series had to be fitted on the PC board where space was provided for one, which is not very tidy.

The ammeter shunt resistance calculation on page 78 is wrong. For a meter of 200mV FSD the shunt should be 0.01W (200mV divided by 20A), not 0.0125W. The wire supplied therefore should be 200mm, not 250mm long if its resistance is 0.05W per metre. If it is left at 250mm the meter will read over-scale (displaying "1.") at only 16A. Alternatively, if full scale is to be 25A, then the shunt should be cut shorter to give only 0.008W, or 160mm. I left it at 200mm to read full scale at 20A.

The Oatley shunt board was easy enough to make but there are some vital instructions left out. This board is apparently intended to be used over a wide range of meter full-scale values and there are six PC board points intended for fitting of links or jumpers to cater for the various possibilities. There are no instructions except a circuit diagram, from which the user has to work out the intentions of the designer, bless him.

For this application, links have to be fitted between A and C and between B and F. In addition, there is a final trimming adjustment in the form of a 10kW pot across the shunt to compensate for minor errors in the shunt resistance value.

The ammeter DPM can be left to read 200mV FSD but the decimal point jumpers have to be set to display 19.9 instead of 199, etc as per the brief instruction sheet.

The above all sounds logical enough in hindsight but in order to get there I had to partially dismantle the whole thing in order to diagnose the reason for crazy displays when first assembled to instructions. The shunt board was first unsoldered from the ammeter DPM, the shunt was removed from the screw terminals and re-cut, and PC board posts were soldered into the six holes A-F.

Next, the 10MW and 100kW resistors R_A and R_B on the voltmeter board had to be removed and the board tidied up and examined for damage. Finally, the shunt board was temporarily connected again to the DPM posts via 150mm lengths of wire so the whole project could be tested and calibrated in an open state, and the various jumper settings verified without having to unsolder the two boards again.

In retrospect, the final calibration of the two meters was relatively easy. For current, I used a 2A 0-16V lab power supply working through a large 0-20W wire-wound rheostat for low end calibration, and a 12V SLA battery loaded up by a variable length of large gauge resistance wire for the high end.

In each case, my "substandard" against which calibration was done was the best available DMM or other bench meter that I could lay my hands on.

After plotting and averaging, I think I’ve ended up with a couple of meters that will read around ±2.5% of true voltage or current. NATA, look out.

Bruce Rabbidge,
St Ives, NSW.

Comment: what can we say? The supplied instructions with the panel meters are very poor and our article should have compensated for those shortcomings.

Cheap multimeters can
double as panel meters

Recently, I thought about building your simple panel meter project from the March 2007 issue. Then I was in a local shop called "Cheap As Chips" and noticed small pocket digital multimeters for $5.00 each. DT810B was the model number on the meters and the product code HA3068.

These meters had a 10A range so I purchased two for $10.00 a pair, wired them up so one was a 20V voltmeter and the other a 10A ammeter. The whole unit then only measures 90 x 95mm. They use an A23 12V battery in each meter.

For the meter used as 10A meter, I wired heavy leads to the terminals on the PC board, as the tracks are a little thin. This makes a very cheap project. One wonders what these meters really cost to produce in China.

Keep up the good magazine. I started with Radio & Hobbies magazine then Electronics Australia and now SILICON CHIP. I have been following these magazines for just over 40 years.

D. L. Bishop,
Yorketown, SA.

We have a long way to go
with energy conservation

I recently attended the pool and spa show where the majority of the displays were spas. A lot of interest was being shown in the spas, so out of curiosity I looked at the specifications of a medium to large size spa. It had three motors, one 5HP and two 3.5HP.

This is just to run the jets. How much more energy is used in heating the water and keeping it at a comfortable temperature? The government is going to do away with incandescent lamps but how many houses are going to have to convert to fluorescent or LED lighting just to equal the energy used in one of these spas?

Glen Williams,
Heathcote, NSW.

 

No more class-A
amplifiers please!

Can you please produce a project that is a different kind of amplifier than the stock standard class-A, B and AB designs (for example, your current 20W class-A amplifier)? Almost every amplifier design by your magazine is textbook stuff and to me is very boring.

How about something more technical that is not written in detail in most texts, like class-D which uses pulse width modulation? There are quite a few manufacturers making class-D ICs.

Besides class-D, I have read application notes that suggest using accelerometers mounted to the speaker drum to provide feedback of the speaker’s motion, which could possibly be used to produce very low frequency amplification. I would like to see an all-digital amplifier that takes MP3 data source in digital format and drives the speaker using pulse code modulation.

Having said all that, I suppose a
class-A amplifier is still good introduction to electronics for students and hobbyists and the latest design has very low distortion.

J. Dickson,
via email.

Comment: we have spent quite a bit of development time with class-D chips but we found them unreliable – they kept blowing up. Also their distortion is nowhere near as good as a good class-B design, let alone class-A. We are aware that there are many consumer products now with class-D amplifiers but their sound quality generally leaves a great deal to be desired.

The idea of using accelerometers to provide motional feedback for speakers is quite old and has yet to be applied successfully in commercial speakers, to our knowledge. Philips did have a very good range of motional feedback speakers about 25 years ago but they have long since been discontinued.

 

Electron flow versus conventional current flow

As a scientist and an electronics hobbyist, I am interested to know why electronics people talk of current flow from positive to negative, whereas scientists talk of current as electron flow from negative to positive. I am thinking that only one of these is actually correct and if that is the case, why isn’t a consistent standard in place, preferably with the correct method of current movement along a conductor?

I don’t regard the fact that the symbols are wrong, if electron flow is correct as I suspect, as being a good reason to propagate incorrect information to those learning the trade. Information, in all fields of human endeavour, is constantly being updated and corrected, sometimes quite radically and I see no reason why the electronics industry should be different. This might make for an interesting article or editorial.

Robert Oliver,
Perth, WA.

Comment: conventional current flow
has always been from positive to negative, in spite of electron flow being the reverse. Most people tend to prefer the concept of something flowing from a positive potential to a negative potential. If electrons had been discovered when batteries were first being developed, then no doubt conventional current flow would be the same as electron flow.

Unless there is a move by some international standards body to establish electron flow as the "standard", there is not likely to be any support for a change. Such a change would have far-reaching consequences; even the arrow on transistors and FETs would need to be changed in direction.

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