Battery operated centrifuge for cell separation in fluid suspension.

Step 11: Long arm paperclip (14 cm) with tachometer

This image shows the "long" paperclip rotor arm (see "arch" to left, beyond lid of tin) which measured up to 14 cm from the center spindle of the DC motor. You can see the tachometer at the top of the image. With two 9 volt batteries in series or a 12-24 volt DC power supply this will "Tach" up to 2000 RPM for about 600 g's. Spinning it up that fast requires that you at least Duct Tape the unit down to a surface (and wear Goggles).