Who we are & What we do
We like to invent things and make improvements to existing
products - this is how Stir-Plate.com came about. We were originally interested
in purchasing a couple of stir plates for yeast propagation but quickly
discovered that a commercial stir plate can cost $300.00 or more! Then we did
some chasing on the net and discovered that a lot of people were building their
own stir plates using an old PC cooling fan, used hard drive magnets and were
using a variety of methods to vary the fan motor speed. We built a few stir
plates based on designs off the net but we really weren't happy with any of them
- each one had "issues".
Our Stir Plate Development
06/09/2009 - First Working stir plate
After a little bit of work, we produced our first working stir plate.
06/10/2009 - Finalizing Design
While working on the prototype, we were also designing the circuit
card, sourcing parts and deciding which magnets and stir bars would work
best for our stir plates.
chose FR4 material with 1 ounce copper for the controller card.
Construction is double sided SMOBC with solder mask on both
These are industry standards for any high end equipment and the
circuit card is rugged enough to last many years of service.
view populated with components.
And no, that part with the fin on the top, right corner is not a
LM317 voltage regulator!
It's the power transistor that's used to pulse power to the
And notice - no heat sink - none needed. Everything including
the power transistor stays cool to the touch.
06/13/2009 - Prototype in initial Box
We sourced an initial box to build the next prototype in, including
mounting the speed control, power switch and power on indicator.
06/18/2009 - Final Version in Production Box
We found a box we like. It's compact enough to not take up much space
but large enough to contain everything.
Prototype and production boxes side by side.
Final product with 2000 ml flask
Our latest design improvements
The most obvious change
from the outside is the absence of a power switch. We have
incorporated the power switch into the speed control knob. Now
you turn the knob all the way counter clockwise and "click", it
turns off. Then you just turn the knob back clockwise to turn
the power back on.
On the inside
We were using 4 machine screws and nuts to mount the motor
but an early customer return convinced us to come up with a
better solution. The motor had loosened up with use. Now we
mount the motor with 4 aluminum rivets. Since the rivets are not
threaded, they can-not loosen and the motor stays tightly
fastened to the frame.
We discovered that changes in line voltage could change the
speed of our stir plate so we switched to an energy star rated
regulated 12 VDC power supply. These supplies cost a few dollars
more than an unregulated 12 VDC power supply but now changes in
line voltage have no affect on our stir plate speed setting.
Jan 2010 Manufacturing Issues
With help from our distributor, we identified a manufacturing
issue with our stir plates. The bond between the motor and
magnet cross bar was not strong enough to survive rougher than
usual shipping. We have changed our manufacturing process to
solve this issue and all new product is OK, but there may still
be some failures in the field.
If you bought your stir plate from one of our resellers and
the stir bar has stopped spinning you can return the stir plate
to them for replacement. For even faster service, we'd rather
you return your stir plate directly to us. We will repair your
stir plate and ship it directly back to you the next business
Note: Repaired stir plates will be shipped back with the
accessories they were shipped in with. In other words, only ship
us the actual stir plate and we will only return the repaired
stir plate to you.
40 Stir plates that
have passed run-in & final test and are ready to ship to our
These have all been modified to prevent the cross bar from
separating from the motor in shipping.
June 2010 - Stir-Plate 3000
We finally finished the prototype of our latest stir plate.
This stir plate measures 8" wide by 7" from front to back, large enough to
safely support even a 6 liter starter.
Also, the motor & PWM control provide more than twice the torque that our
original stir plate produces.
March 2011 - All stir plates
We just finished our latest controller
card design with new enhancements like
better speed regulation and more
sensitive speed adjustment. This new
controller will phase in sometime during
the summer or fall with all stir plates
using the new design once the controller
is phased in.
As of this month all of our stir plates
have a warranty statement label applied
to the bottom. This is a direct result
of feedback we received from one of the
brew boards. A customer bought his stir
plate from his local homebrew shop and
unfortunately it was defective. He did
not know what to do with the stir plate
because before now our warranty
statement has only been on-line.
Stir Plate Product Warranty
This product is covered by a one
year workmanship defect
warranty. Your stir plate
warranty extends one year past
your purchase date or 18 months
from the manufacture date.
To claim your warranty, ship
your defective stir plate along
with a note explaining the
defect and a copy of your
purchase receipt to the address
listed on the
stir-plate.com web site. If
returned without a valid
receipt, the manufacturing date
code will be used to determine
stir-plate.com is not
responsible for warranty return
freight but will cover freight
back to you. Repaired and / or
replacement product will be
returned as shipped to us. For
example, a stir plate shipped in
without stir bars will be
returned without stir bars.
This warranty does not cover
user abuse, damage from
incorrect power supply or
expectations. For example,
expecting a SP-2000 to spin a 5
liter starter as well as a
SP-3000 spins a 5 liter starter.
2011 - Rev B Controller Card Released
We finished evalating our latest
generation stir plate controller card
and from July 2011 on, all SP-3000 stir
plates will be manufactured with the new
controller. SP-2000 stir plates will be
manufactured with the previous
generation controller card until we
consume all old stock. Stir plates built
with the new rev B controller card will
have a B marked on the back panel.
But why did we change the
First, you need to understand
that there is nothing wrong with the old
controller card and if you own a sir
plate with the old card it will continue
to deliver years of trouble free
service. We re-designed the controller
card for no other reason than we believe
in continuous improvement.
So, what's new with the
1) The new controller allows us
to use a broader range of power supplies
which helps us control our price to you
as the cost of everything else
increases. This helps keep us
competative as the cheap stir plate
manufacturers are forced to raise their
prices because they are locked into the
cheapest of everything.
2) Speed adjustment is more sensitive.
Also, you can now set your stir plate to
much slower and higher speeds than
3) Speed is more stable. The previous
version locked us into using regulated
power supplies in the 9VDC to 12VDC
range to keep set speed stable. The new
design is just as happy with regulated
or non-regulated supplies.
Released our new Black MAXX
See the separate article on our
Black MAXX Stir Plate Page.
2011 - Rev B Controller Card Update
During the first week we will build the
last Stir Plate 2000 models with the old
controller card and everything will have
switched over to the new Rev B
- Postal address
12021 South Memorial Pkwy, Suite N-4, Huntsville, AL 35803
- Electronic mail
- General Information:
Copyright © 2009 - 2011