Publisher & Editor-in-Chief
PUBLISHER'S LETTER
Leo Simpson, B.Bus.
Editor
Greg Swain, B.Sc.(Hons.)
Technical Staff
John Clarke, B.E .(Elec.)
Robert Flynn
Darren Yates
Reader Services
Ann Jenkinson
Sales & Marketing Mgr.
Angela Clarke, B.A.(Comm .)
Phone (02) 979 5644
Mobile phone (018) 28 5532
Regular Contributors
Being cautious with electromagnetic fields
This month, we are publishing a magnetic field meter with LCD readout.
It is intended for measuring the magnetic fields emitted by all mains
operated appliances and computer and video monitors. A number of
readers have asked us to do a feature on this subject and it is one that is hard
to ignore since it has been covered very thoroughly by such eminent
journals such as "Electronics World + Wireless World" and "IEEE Spectrum".
Up till now though, we have devoted little space to this sensitive subject
because the evidence that 50Hz magnetic fields are harmful is still pretty
tenuous. Now before all those people who believe that these fields are
positively harmful jump up in a rage, let me state that the statistical
evidence for such conclusions is "right down in the noise". The message so
far seems to be that yes, there is some correlation between exposure to
magnetic fields and some cancers and some other biological effects. And
since no-one knows what the safe long-term exposure levels are, there is a
move to minimise the emissions from all electrical and electronic equipment. Hence, in order to be able to measure these fields, we have published
the magnetic field meter.
However, having published the meter, we would caution people about
becoming paranoid about 50Hz magnetic fields. There are far worse forms of
radiation to which we are all exposed and we would be far better minimising those.
For example, rather than worry about the very low level of 50Hz fields
which might be emitted by your computer or its monitor, consider that your
low voltage halogen desk lamp may be emitting high levels of ultraviolet
radiation which definitely can harm your vision. To a lesser extent, the
same can be said of fluorescent desk lamps. Or when you are out driving in
traffic, close your car's windows and put the ventilation or airconditioning
on "recycle" so that you are not exposed to carbon monoxide and lead
emissions. Compared with these hazards and many others, 50Hz magnetic
fields seem pretty innocuous.
So by all means, build the magnetic field meter and if you are so inclined,
arrange your household appliances to minimise your exposure. But don't go
as far as some people and refuse to use appliances at all because of their
magnetic emissions. That is being paranoid.
Leo Simpson
Brendan Akhurst
Jennifer Bonnitcha, B.A.
Garry Cratt, VK2YBX
John Hill
Jim Lawler, MTETIA
Bryan Maher, M.E., B.Sc.
Jim Yalden, VK2YGY
Bob Young
Photography
Stuart Bryce
Editorial Advisory Panel
Philip Watson, MIREE, VK2ZPW
Norman Marks
Steve Payor, B.Sc. , B.E.
SILICON CHIP is published 12 times
a year by Silicon Chip Publications
Pty Ltd. All material copyright ©. No
part of this publication may be reproduced without prior written consent of the publisher.
Printing: Magazine Printers Pty Ltd,
Alexandria, NSW; Macquarie Print,
Dubbo, NSW.
Distribution: Network Distribution
Company.
Subscription rates: $42 per year
in Australia. For overseas rates, refer to the subscription page in this
issue.
Liability: Devices or circuits described in SILICON CHIP may be
covered by patents. SILICON CHIP
disclaims any liability for the infringement of such patents by the manufacturing or se lling of any such
equipment.
Editorial & advertising offices:
Unit 1a/77-79 Bassett Street, Mona
Vale, NSW 2103. Postal address:
PO Box 139, Collaroy Beach, NSW
2097. Phone (02) 979 5644. Fax
(02) 979 6503.
ISSN 1030-2662
O CTOBER 1991
3
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