Some time previous to getting my ham license, I was at a friends house who showed me an LC (inductance) meter built from a kit. It was based on a PIC16C22A, and I certainly do like the PIC mcu's, but decided I would embark on the task of re-engineering my own that uses an Atmel AVR chip, the Atmega168. It's been a journey. Also, I am giving away for free the schematics, firmware, and source code as open source under the GPL.
|
Inductance, Capacitance, LC Meter
|
|
|
Here is a new desoldering tweezer tool I just made, it's rough and there will be improvements, very likely. It looks kind of dangerous, but it's really low voltage, under a volt, barely enough to register on my digital voltmeter.
These tools cost hundreds of dollars if you want to buy them somewhere, but I made mine out of cheap radio shack parts and junk. The power supply is also homebuilt, which I also use for my hot air pencil . In the lower part of the photo, what looks like sawdust, is a bunch of resistors that I desoldered in just a few minutes.
Click on any of the pictures for a larger view.
|
Desoldering Tweezers
|
|
|
I've long been a fan of solderless breadboarding. And frankly any kind of breadboarding, even the soldering type. When you need to whip out a circuit fast, don't have time to etch a board, here are some of my tricks.
|
Recycling old ISA cards
|
|
|
Here are more details on my hot wire foam cutting table. I show the details of the terminals attaching the hot wire at top and bottom. The bow is made of threaded rod so adjusting an angle on the wire is trivial.
|
Hot wire cutting bow,
top terminal
|
|
|
| Here is a jacob's ladder I made, and I added a little circuitry to make
it act as a speaker. Then, of course, the best thing to do next was
play the song "We Are Climbing Jacob's Ladder" through it. The sound
is a bit quiet in the background, but it's there, and it's all produced
by the arc. Enjoy. |
|
|
|
Most of us think of complicated electronics, computer modules and such,
when the subject of ignition systems arises. Even I'll admit that the
electronic engine control systems on today's cars are a bit beyond my
patience to understand. But now, could the fixed advance spark timing
on a single-cylinder small engine be really that bad?
Well, I've had a chance to find out. The official results are in. Small
engine ignition is simple. Below is a 'case study' of a conversion of a
12 horsepower lawn tractor engine to solid state, hall effect sensor
based, transistorized battery ignition. The picture shows the homebuilt
module in place, housed in an electrical box with aluminum cover plate.
The black strip is simply a piece of electrical tape to cover some
mounting holes. |
Homebuilt Solid State Ignition Module, housed in electrical box
|
|
|
This design is a result of small scale experimentation. I originally
wanted to use SCRs because of the simplicity of the design. But it
turns out that low cost, readily available SCRs do not handle a
frequency high enough to heat small crucibles full of metal, nothing
above 10KHz. My application induction of heating requires frequencies
between 200kHz and 1Mhz. So I turned to MOSFET devices and a self
resonant circuit made the most sense.
Please note that this circuit is conceptual only. Please do not email
me asking for part numbers and component values. They will not do you
any good! I have experimented using small devices, and because the
circuit is still under development, you should not take this
information as how-to! This page is here only to detail my research,
experiments, and observations.
Below is my understanding and explanation of the circuit's operation.
For those of you who know more about induction heating than I do,
please
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
|
A conceptual MOSFET self resonant oscillator
|
|
|
It was a dark and stormy night...and the 3-watt generator lamp was
sporadic, cutting out altogether each time a whiff of snow happened to
come between its roller and the tire. "There's got to be something
better," the mad cyclist thinks to himself as he squints to make out
the faint halo of light cast by the 3-watt bottle dynamo generator.
That
mad cyclist happened to be yours truly, and the above situation real to
life--and the inspiration for the MONSTER Quartz Halogen Bike Light!
The
cost of this project was somewhere around $100. I say 'around' because
I already had some of the hardware. But I try to figure that in to the
above amount!
|
Great ball o' fire, it is!
|
|
|
Notes on converting that old compact tv set or computer monitor into an
oscilloscope. Proves very useful in line quality monitoring and other
low frequency applications.
Here is a picture of the scope I built when I was 15 years old. It was
a 9 inch portable black and white tv set. It was very limited, the beam
only deflected to the positive. That means only one half of ac
waveforms came through visible. The tall object partly obscuring the
screen is the deflection power transistor (there was only one.) The
preamp circuitry for deflection circuit was built on a Radio Shack
solderless breadboard. I used to hook this up to my stereo and watch
the dancing waveforms of the sound. This picture is the only one I had
of a homemade o-scope, but I've also converted several computer
monitors.
Warning!!! Please note!!! There are high voltages inside tv sets! Use
extreme caution! My advice is, never reach into the unit while it is
plugged in unless you are real sure of what you are doing! I accept no
liability whatsoever for the risks you take in following the plans
outlined below. Not all tv sets and computer monitors are alike, so
these plans are only exemplary of one way you might do this. |
Miniature TV converted to oscilloscope
|
|
|
Build your own arc welder! Many of you have been so patiently waiting the arrival of these DETAILED PLANS that you can purchase and download (4.6MB pdf!) for a small fee.
You
get 90 pages of high quality color illustrations, photos, construction
notes, and all the FAQ's, in printer-friendly pdf format. And MUCH more
information than the free (read: skinny) version below. |
Detailed plans now available
|
|
|
| This article is about my adventures in foam cutting with a hot wire method. Here is a homebuilt foam turning lathe!! This is made from a window
motor adapted and appropriately painted for the application. The pillow
blocks that the rotating shaft bear in were made from foam patterns and
cast using the above mentioned techniques. |
A foam cutting lathe?!
|
|
|
| You've probably seen how that modern circuit boards are all made with
the new (or maybe I'm just old?) surface mount technology, or SMT.
Well, what's a guy supposed to do when he wants to salvage SMT
components from such "modern" boards? The commercially available
hot-air tools are quite expensive, in the hundreds of dollars, some
even thousands. Hmm. I wonder if I could make one...why not? The
following is a not-yet-complete story of one in the making. |
Low cost homebuilt hot air tool works wonderfully
|
|
|
| Haven't you always wondered what's inside an external hard drive,
especially those portable USB-powered ones? You're about to find out. |
Let's hack a USB hard drive! |
|
|
|
