HOME Schematics Discover Forum Hobby Corner Dave's Circuits Electronic Resources Contact Info


4th Quarter - 2012- Page 1                                                                                                                  Previous Issues     
  

Let's drop in on Wily and look over his shoulder at his latest project....

TITLE

Text here....
con't page 7

Wily Widget,
the Lone Inventor
 with Gadget & Gizmo

WHAT THE WORLD NEEDS NOW is ... An 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....
story con't on page 6

Home Made Current Transformers
By: Dave Johnson

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....

   story con't on page 4

Inferior 50 Ohm Power Load Resistor       
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....

 story con't on page 3

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....


story con't on page 5    


4th Quarter -  2012    

Index Circuit
Diagnosis
Experimenter's
Corner
Good Idea
gone Badly
What the World
needs Now
Wily Widget


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy

Copyright  2002 - 2015 David A. Johnson & Associates.  All Rights reserved. 
 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.