Simple speed control
Simple speed control
(OP)
I'm trying to find a simple (reads "cheap") way of putting together an experimental setup where I can spin a flat surface (less than 4") to spread liquid on it. Max speed I need to achive is about 4000rpm. The load is almost negligable compared to motor rotor's own inertia probably. Most critical restriction is being able to start from zero speed and accelerate slowly to max speed. I cannot simply start from few hundred rpm. Could I simply get any DC motor and regulate the speed with input voltage? Can I add an additional weight to slow down the start up speed? Brushless vs brushed motors? I do not want to spend $2K plus to get a driver/controller/motor setups to experiment. Any input is appreciated. Thanks.
Ruhi
Ruhi





RE: Simple speed control
Lance
RE: Simple speed control
I'm not an expert on motors but I would guess that a DC motor would do the trick. 4000 rpm seems a bit high for common dc motors. I haven't heard of a brushless DC motor. You could use a simple bench adjustable DC power supply or a SCR speed controller. Be sure that the DC supply has enough voltage and current to supply the motor. Here is a link to a vendors DC motor info http://www.grainger.com/Grainger/static.jsp?page=rc_dcmotorgd.html that describes in a short form three kinds of DC motors.
RE: Simple speed control
What you need is one of the combination ac/dc mains operated brush type motors. These are commonly found in household appliances such as vacuum cleaners and so on. They usually rotate at fairly high speeds, typically 10,000 to 15,000 RPM, but the big advantage is that the speed can be controlled by simply varying the supply voltage. This is something you cannot do with an induction motor.
If it was me, I would go out and buy a cheap router, and mount it somehow spindle upwards. You could then mount your disk in the very nice chuck provided on the router shaft. This will probably spin at 12,000 RPM or something.
You then find a sufficiently rated lamp dimmer, or motor speed controller, or maybe you might have a variac in your lab somewhere ?
Anyhow, you will be able to adjust your speed right down to zero. Two notes of caution. First at reduced speed there will be little airflow through the motor windings, but there will also be little power or load, so it should be o/k. Secondly speed control may not be smooth at low speed, and you might need a small flywheel to smooth it out.
Cheers, Tony.
RE: Simple speed control
http://www.thomasregister.com
and type Motors: DC under Product or Service, which will return 293 companies to approach to