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Let's drop in on Wily and
look over his shoulder at his latest project.... |
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Wily Widget,
the Lone Inventor
with Gadget & Gizmo |
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WHAT
THE WORLD NEEDS NOW isAn Anti-Theft
Hanging Basket Alarm |
A while
back I received a call from a woman who was in tears while describing a
problem she had. She had a number of expensive plants hanging from her
home’s front porch. It seemed that within weeks of her placing a new
plant on a hook near her front door, it would be stolen. She walked
all around her neighborhood but could not tell who was taking her plants.
No one else had similar plants. She figured that the thief was in the
neighborhood but they were putting the stolen plants inside their home or in
their back yard, out of sight. She wanted to know if there was
something she could do to prevent future thefts and perhaps identify the
thief. I gave it some thought.... |
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Home
Made Current Transformers
By: Dave Johnson |
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A
while back I got call from someone who wanted to monitor the AC current going
through a power line, using a current transformer. He found some nice
commercial snap-on current transformers but they were all selling for about
$25 each. He wanted to know if he could somehow build his own
transformer. Some time back I had to do just that. I needed to
light an LED when AC current was flowing through a wire. I looked around
in my lab inventory and found a few snap-on split ferrite cores like the
photos below. These components are normally used as RF filtering
devices. They are often used on video cables, USB cables and some power
supply cables. They help to suppress RF, which might leak out of or leak
into sensitive circuits. Split ferrite cores are more convenient since
they can easily be clipped onto an insulated wire carrying 50Hz or 60Hz AC.
This allows some AC voltage, generated by the AC current flowing through a
wire, without actually touching the copper conductor. This is a much
safer way to monitor AC current.... |
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Inferior
50 Ohm Power Load Resistor
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I received
a call from a ham radio operator. He was testing some older vacuum tube
type radio transmitters, using a classic 100W 50 ohm power resistor, immersed
in mineral oil. This “cantenna” dummy load allows testing without actually
transmitting RF out into the ether. The caller said that at 1.6MHz, the
160 meter band, the load seemed to work about right but when he went to higher
frequencies, he could no longer get the transmitter to tune properly. In
theory, the load resistor should have looked to the transmitter as a perfect
50 ohm impedance. I asked him about the nature of the resistors he used
to build his load bank. At first it seemed reasonable but then I asked
an important question. I asked him if the resistors were the
“non-inductive” type. He didn’t know. I suspected that they were
not.... |
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Pirated
Audio Books |
I love
audio books. I often listen to a book when I take my walks and when I
have long soldering sessions. I usually buy my CD books on eBay and
convert them to MP3 for my portable players. Sometimes I buy books
already in the MP3 format. This save me a lot of time since all I have
to do is copy the files from the CD to my MP3 player. Lately, I have
seen a rash of books which are sold as new but are in fact pirated copies.
They come in convincing shrink wrap covers and original looking boxes with
color title covers. But, inside is a cheap CD with a paper label.... |
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