[Oberon] A universal control for laboratory centrifuges.

[peter at easthope.ca]

A vexing problem with contemporary centrifuges is failure of the 
control system while housing, motor and mechanical components remain 
in almost new condition.  A machine that will cost 8-20 k$ to replace 
becomes unusable from failure of a capacitor or integrated circuit 
worth pennies to a few dollars.

From:	Chris Burrows <chris at cfbsoftware.com>
Date:	Sat, 18 Nov 2017 10:52:50 +1030
> We have now added real-time time and date support for RISC5 FPGA 
> Project Oberon systems ...

Time and speed are the salient parameters of a centrifuge.  Typically 
the user sets duration and speed of a spin.  Some machines have a 
refrigeration unit allowing control of temperature.  Some machines 
have an accelerometer to detect rotor imbalance.

For example, an instruction manual for an IEC machine specified 
replacement of the main p.c.b. in case of failure of power supply to 
the motor.  Unfortunately the board is not available.  For another 
machine, purchased about a decade ago, no parts are available. 
Schematics for the boards are not available, components are surface 
mounted and some components have o.e.m. markings which can't be 
traced.  Under these conditions, troubleshooting a board manifesting 
intermittent failure can be impractical.

So I wonder about feasibility of a universal control for a centrifuge, 
built from inexpensive components and software.  Tachometry is 
commonly done by counting and timing pulses from an encoder wheel, 
similar to the wheel in a mechanical mouse.  Temperature is sensed as 
a voltage from a transducer.  Rotor imbalance might also be detected 
as  voltage. 

This isn't a one-off project.  World-wide, thousands of centrifuges 
are built annually.  Seems that a universal control kit might be a 
viable commercial product. 

Regards,                ... Lyall E.
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