DC Motors

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I thought I saw a post about using dc motors to power home made power tools, but ended up with nothing in the search. I have run across some motors that I would like to use for a large sander project. Do I just use an ac-to-dc converter? The dc voltage input spec on the motor is (around) 150vdc. If I use a lower voltage, will I need massive current, or will it just spin slower? I thank you for any help in advance.
Reply:You're correct that using a lower voltage than specified will cause the motor to pull more amps and possibly burn out itself or the power supply.    You can use a universal type motor, but larger ones are tough ($$) to find.     I'd recommend looking into a PWM (Pulse Width Modulation) DC Motor speed control.    A PWM controller applied the full voltage, but switches it on and off at a high frequency.    This allows your motor to pull the correct amps, thus the correct torque, but controls how fast the motor rotates.      A few years ago, I built a wide format sander.   To drive the sanding drum, I used a 2 hp, 220v, AC motor and to drive the feed belt, I used a 1/4hp, 24v DC motor with a gear reduction head.  To control the feed belt speed, I used a homemade PWM controller.There are no small projects
Reply:How complicated is the pwm powersupply?
Reply:Basically, it's an oscillator, the frequency of which is controlled by a variable resistor and capacitor timer.   The oscillator goes back and forth between two states, "ON" and "OFF".   Each "ON" state, triggers a gate (either directly or by providing a path to ground) on a MOSFET (a power transistor), that completes the circuit between the power supply and the DC motor.      The MOSFET has to be able to handle the current that the motor will draw and will most likely require a heat sink.    The oscillator output may have to be amplified to provide enough forward voltage to trigger the transistor gate.   Building one isn't difficult, an hour or two, tops.   A PWM controller, capable of handling up to 35vdc at 10 amps, cost less than $5 in parts from online sources.   There are build it yourself kits available too.    Check out KITSRUS.com for one.   I've got a few other sources in my directory at home, I add them tonight.Another option is to look for a commercially available PWM controller that meets your needs.    Dart is one manufacturer that offers DC motor controllers that can handle a wide range of voltages and currents.    I know I refer back to Ebay too often, but I have seen several Dart controllers for auction at reasonable prices.There are no small projects
Reply:These are a few resources for PWM circuits.    http://www.imagineeringezine.com/e-z...hot%20Circuitshttp://delabs.tripod.com/cirdir/index.htmlhttp://www.aaroncake.net/circuits/http://www.solorb.com/elect/solarcirc/pwm1/http://www.dprg.org/tutorials/2005-11a/index.htmlhttp://www.discovercircuits.com/P/pwm.htmThere is another type of DC speed control thats know as an SCR type.  Theses are an older design and are based on Silicon Controlled Rectifiers.   I see these more frequently (and more inexpensive) on Ebay, but I have no experience with them.Good LuckThere are no small projects