>>>READER-TO-READER QUESTIONS AND ANSWERS
convert HDMI to IEEE?
There is not a circuit or device to
convert HDMI to IEEE because IEEE
stands for Institute of Electrical and
Electronics Engineers, an international
nonprofit organization ( www.ieee./
org). This is not a protocol/specifica-tion such as HDMI (High-Definition
Multimedia Interface). You must add
a series of numbers after "IEEE" to
refer to a particular standard such as
IEEE 488, IEEE 802.11, IEEE 1394, and
HDMI is a licensed interface
which uses uncompressed and
encrypted data to interface DRM
(Digital Rights Management)
audio-video devices/sources including
computers and satellite dish systems
to compatible televisions, audio
devices, etc. Due to the DRM aspect,
it is not likely possible or legal to
convert HDMI to some other form of
signal (digital or analog) to bypass the
have found that Tarn-X will remove the
oxidation (the part must be water
washed and dried afterwards).
Solder tinning has just about gone
away due to RoHS (the Reduction of
Hazardous Substances initiatives in
Europe and California). Everyone is
afraid of lead these days, and
traditional solders are an alloy of tin
and lead. Most parts are now tinned
with pure tin (now you know where
the term "tinning" originated!).
Pure tin is showing some longetiv-ity problems in that it tends to whisker
over time and on close pitch parts, can
cause an early device failure. Parts
tinned with solder do not seem to
exhibit this problem. Although the
agencies pushing elimination of
lead have exempted components
used in military and communications
applications, most manufacturers are
only making the lead free variety now,
as it is cost-prohibitive to run two
parallel production processes for the
same base part.
For more information on RoHS,
was developed to have the same
coefficient of expansion as glass.
This made it possible to bring wire
leads out of glass sealed units without
leakage. This wire is cheap and readily
available, probably less expensive
than copper. It is also magnetic.
Carbon film resistors are fabricated on
a ceramic core. The end cap that
holds the core is steel and is magnetic.
The end cap makes the connection
between the carbon film and the
#3 Copper is not used because of
the cost and the added heat
conduction is not needed. In most
applications in PCBs, the leads are
so short that it wouldn't make any
difference in the heat dissipation
capability of the device.
[#12071 - December 2007]
I have noticed that many of the
leads on capacitors and LEDs are
magnetic, as are the bodies of carbon-film resistors (but not the leads). Why is
that? Why not copper wire? Why is
there iron in a carbon film resistor?
#2 Many years ago, an iron alloy
#4 On capacitors, LEDs, and many
transistors, the leads are also the
physical support. For example, a TO- 5
cased transistor running at its power
limit might be mounted high off the
circuit board and have a "flag" style
heatsink. Copper leads wouldn't be
Figure 1 is the correct schematic.
The text of my answer remains the
#1 Many of the leads are magnetic
because they are made of steel.
This steel is then "tinned" with either
solder, pure tin, silver, or gold. One
would suspect the reason for using a
"base metal" such as steel would be
material cost, but actually it is so there
is the correct tensile strength to allow
for bending prior to insertion in a
circuit board. The leads are tinned to
make soldering more efficient.
Solder adheres very well to gold, silver,
Many mil-spec semis have gold
tinned leads. Some have silver tinning.
If these have been in storage a while,
they will oxidize and turn black (just
like silverware does) and solder will
no longer stick. To use these parts,
the leads must be cleaned, either
manually using an "Eraser" brush, or I
There is an error in the schematic diagram accompanying my answer
in the November issue to question
February 2008 93