Tesla Coil Theory
How does a Tesla coil actually
work? I’m especially interested in the
relationship between the primary
winding and secondary winding that
creates the spark.
#11131 Brian Miller
St. Paul, MN
I want to rotate one 40 lb metal triangle up 90°. Its base will be connected by a hinge to the base of another
triangle. The base is 67.88"; the other
legs being 48", and a height of 57.87".
By rotating the apex of the triangle 90°,
the apex would travel an arc by 8. 18 ft.
I intend to use two sprockets and a
chain connected to a motor. What size
motor will I need to use to complete
this and how is it determined? I understand w = fd and P = fd/t. I would like
the time to be six seconds.
Can someone please help with
the answer and also show me how to
figure this problem out for myself?
Filter Caps and Power Supplies
This has to do with electrolytic
aluminum filter caps for switching
No matter what type filter cap I
try, they blow out (become pregnant)
after months or a few years. I repaired
cable boxes for many years that had
the exact same problem.
This is only a three volt supply at
about two amps. Ten volt 1,000 mfd
caps are used in the stock supply.
Also, a three amp Schottky diode
(burns up) supplies the DC to a 15
amp logic N-channel MOSFET with a
heatsink. It gets hot. Then, the output
of it gets a cap, a choke, and a cap.
Nicely filtered three volts.
This is my final change-out and it
is lasting the longest. So far, no blow
outs, but it has only been seven
Now, the two five amp Schottky
diodes in parallel. Using only one still
gets super hot. Caps 25 volt at 1,000
mfd. I’m only using general type filter
caps at 20% 105° C. Why has this
been such a big problem?
The cap that usually blows is the
first one after the MOSFET. I see no
spikes on the output of the MOSFET
either. I could use a TO-220 pack with
dual diodes in it, but no room. The
two 5 amp in parallel work just great
and only get warm.
#11133 Dan Zielinski
Port Saint Lucie, FL
[#9131 - September 2013]
I've finally used up my 2 lb roll of
Kester lead-based solder and I'm ready
to move to lead-free soldering. Is there
anything I need to do to my existing
soldering equipment to make the
move? Anything else I should know?
Making the move to leadless
soldering is a great idea, given the
health concerns of lead toxicity —
especially if you have children in the
house or workshop. It's important to
note that the rosin used as a flux in
solder can be just as problematic as
the lead. You can end up with an
asthma-like condition if you don't work
in a well-ventillated area.
[#10136 - October 2013]
I have a box full of old lithium
batteries. I know they're not supposed
to be put in the normal trash, but I
don't want to pay a fee to have
'hazardous waste' removed. Is there a
safe, environmental friendly way for me
to dispose of the batteries that won't
cost me time and money?
#1 Stores such as Walmart usually
have "fishbowls" at the jewelry counter
for depositing coin batteries. I would
imagine that jewelry stores and hearing aid centers would also have disposal options that may not be limited
to themselves or their customers only.
Worse than coin batteries —
which are used to a lesser extent — D,
C, 9V, and especially AA and AAA
batteries are a bigger problem for
disposal. These days, manufacturers
are using batteries for power far more
than in years past, finding that UL
approval is much easier under battery
power. And if it's electronic, it has a
remote or something wireless and the
larger batteries abound.
Some cities have recycling
centers. Again, Walmart may have a
recycling plan. There are stores that
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78 November 2013