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 RB, RA = 100 K, RB = 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, RA has to be equal to
RB/99.
I decided to use all 1% resistors from Jaycar. RB
would be made from the series combination of 1MW and 820kW, and RA
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 (RA, RB), 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 RA and
RB 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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