I need to know if there are any schematics out there all ready on how to build a simple Variable 0-110VDC Power Supply @ 1A or greater? I am trying to control a 110volt DC/AC @ .75A motor for a Mini Variable Speed Drill Press.
visit to www.epanorama.net you will find schematics of many variable Supply....i think u can use the combination of BUCK and BOOST converters to get 110 variable...but you shud visit that url will learn alot about supplies
Thanks as I checked out the site and I was excited as there was a 300V PS, but it was only .5amps. So I need at least 1amp for the PS as the 110 Volts DC/AC motor needs .75amps to run.
Try googling for 'drill speed controller', it's a common project, and uses phase shifting to trigger a triac or SCR at specific points of the mains cycle.
If you really want variable mains, try searching for 'variac' which is a variable transformer.
If your motor needs to retain torque then you must consider a circuit that will supply constant current throughout the variable voltage range. Some motor speed controllers fall short of that requirement. Choose carefully.
WOW, Thanks guys as I have found a few great idea to at least begin with. But one thing I do know as i will need a constant current to the speed controller. And was thinking about isolating the AC main line going to the AC/DC Motor.
But the cost of adding a Transformer will make it very expensive. Can I add a full wave Bridge Rect in back of the ac main(after main on/off and plug) before going to the SCR circuit, or will this defect the Traic and SCR purpose of speed controling?