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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.

We chose FR4 material with 1 ounce copper for the controller card.

Construction is double sided SMOBC with solder mask on both sides.

These are industry standards for any high end equipment and the circuit card is rugged enough to last many years of service.

Another 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 motor.

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.

500 ml flask on early prototype stir plate

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 first production stir plate together
Prototype and production boxes side by side.

Production stir plate with 2000 ml flask
Final product with 2000 ml flask

Improvements to early stir plate 10/5/09
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 day.

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 ready to ship 1/12/2010

40 Stir plates that have passed run-in & final test and are ready to ship to our distributor

These have all been modified to prevent the cross bar from separating from the motor in shipping.

Stir Plate 3000 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 warranty status. 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 unreasonable product expectations. For example, expecting a SP-2000 to spin a 5 liter starter as well as a SP-3000 spins a 5 liter starter.

 
Jul 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 controller design?

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 controller card?

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 before.
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.
Oct 2011 - Released our new Black MAXX Stir Plate

See the separate article on our Black MAXX Stir Plate Page.
Nov 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 Electrinics.
 

Contact Information

Postal address
12021 South Memorial Pkwy, Suite N-4, Huntsville, AL 35803
Electronic mail
General Information: sales@stir-plate.com
Sales:
sales@stir-plate.com
Copyright 2009 - 2011 Stir-Plate.com
Last modified: 11/01/11