USB powered Cyto Centrifuge
by siderits, published
I used a small DC motor (1.5-6 Volt, 4000 RPM) and a DC motor speed controller kit to make this USB powered Bio-Centrifuge.
The Radius is 40 mm (you can make longer rotor arms) and the motor will spin up to 4000 RPM on 4.5 volt/100 mA USB port power giving a centrifugal force of 500 gravities (link to nomogram and online calculator provided). I used 0.2 ml PCR tubes that when filled weigh-in at about 0.5 gram so at 500 Gravities, each "bucket" will weigh about as much as a half of a 17 ounce bottle of water. The capacitor across the terminals of the small DC motor provides enough energy to keep the motor running smoothly when the armature shoots by the stator and to minimize noise in the circuit (you can look that up for a better explanation than I can give).
Do you see the small piece of reflective tape on the top side of the Right Rotor arm. That's used by the Tachometer to measure the RPM. It tacked out well over 4k RPM (wicked fast).
I used an old USB cable's red and black wire to power it up (with safety gear) and it worked perfectly. Total control over speed.
If placed in an appropriate enclosure (like a metal coffee mug) you've got a cytocentrifuge that actually works and uses only USB power, for under 10 dollars.
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Runs great using a "Minty Boost" as the USB power supply.
I put it in a Metal Coffee mug as a safety enclosure.
Good advice. I suggested putting this in a cookie tin. Truth is it will run off the sun using a harbor frieght solar panel and was conceived for use in countries with restricted economies and open borders in healthcare clinics for cytology specimens. Like so many things on Thingiverse, this is a proof of concept. Sharing ideas and experience to see what others think and what approaches they use is the driving force in the communiy of prototypers. Thanks for your comment. Lets all besafe!
I just love printet things that actually perform a function.
But please be careful out there if you use a real laptop/PC USB port for powering.
I'm referring til startup crurrents, stalled motors and shorts, overloading the USB port can damage it...
Also, you could print an enclosure and perhaps a lid for the centrifuge to make it slighty safer.
Maybe the enclosure would have to be printet in segments to keep the side down.
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Print out 4 of the "Enclosure" walls and 4 supports.
Print out the parts.
Find an old DC motor from a previous project.
Wear safety garb and "spin-r-up"
7.99$ FK804 DC Speed Control PWM from Bakatronics
Kit makes a 0-12 volt output DC Pulse width motor controller.
20 Watt. Great for hand held switching throttles
â€¢ This DC Motor speed control circuit uses pulse width modulation
to control the speed of the motor
â€¢ The potentiometer controls the width of the pulses to control
the speed of the motor or train engine. The Pot can be mounted
remotely on a control panel of in a FB enclosure to make a hand
â€¢ Power supply : 12V. (can also be used with voltages as low as 5 VDC)
â€¢ Recommended housing : FB03
â€¢ PCB dimensions : 1.8â€ X 1.3â€
- 1.5 Amp max current
Add an optional DPDT slide switch for reversing the direction of the motor.
3.00$ DC motor, Find a small DC motor that has speed up to 4k-5k at 1.5-6 Volts.
1 Old USB cables from your abandoned tech box.
Test equipment that I used:
- Centech DT-838 Microprocessor Tachometer
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