In response to Luke Myers' question about motor speed controls,
I will chime in here.  I have been producing electric suction boxes
for years now, and I have built hundreds of my BT-003 speed controller.
I have not seen a failure to date.  I will get a little technical
here, so hold on tight....

All of these motor speed controllers, including the fan speed
controllers, use the same type of solid state device, called a triac.
The triac acts like a very high speed "switch" and it is turned on and
off during the cycle of the applied alternating voltage from the power
mains.  If it turns on a very short time, only a tiny slice of the
alternating current from the line is sent to the motor, so the motor
only receives a small amount of power and runs slowly.  If that
"switch" is turned on for a longer portion of the AC voltage swing,
more power is delivered to the motor and it will run faster.

This motor control technique is the same whether a simple light
dimmer, a fan speed control or my custom speed control is used.  Where
the device differs is in the type of triac used in the controller.
Switching the current on and off into various loads can create
reflected voltage "spikes".  Using a triac switch to switch current
into a lamp creates very little kick back, while switching the current
into a motor can create triac-damaging voltage spikes.

The triac I use has a built in "snubbing circuit" that tends to quiet
these nasty kickback voltages.  From what I've seen in light dimmers
and fan controllers, they tend to use the cheapest triac available and
they don't even have brand name on them.  My triacs are high voltage
(800 volts) and high amperage (12 amps) and are name brand parts.

So what all of this technical talk means is that all speed controllers
are not created equal, and like anything, you get what you pay for.
Robbie was right -- it will work to use a Home Depot speed controller,
but definitely put it in a metal box just in case it decides to melt
down on you.

I had one speed controller returned to me after it was accidentally
wired wrong and connected right across the AC line.  It failed, of
course, but it failed in a very controlled manner and behaved like
a fuse, immediately opening up without any fireworks.

Good luck, Luke, and "May the force be with you."  ("Star Wars" is
being released tomorrow -- I just had to say that!  :-)

Eric Bergstrom - Bergytone Products
Grand Haven, Michigan