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variable speed motor

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Verdict_Guilty

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Hey so im not very good with electronics but im more curious
So my grandad had an old metal lathe which he powered using a washing machine motor he wired it up to have variable speed and also forward and reverse

I was wondering if someone could help explain this to me i will try and get pictures of this tomorow but if anyone knows how to do it i would love to hear

Thanks very much

Jimmy
 

sayf alawneh

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ok u can reverse the motion of any DC motor by simply reversing it poles its known that any dc motor have 2 poles so if u connect one of the poles with the positive of the battery and the other pole with the negative of the battery ur motor will rotate in certain direction let us say in clock wise direction if u reverse the poles of the motor it will rotate in the opposite direction counter clock wise
u can do that simply by using the H bridge just google for
motor dc with H bridge and u will find alot of info
if u dont use microcontroller ur H bridge can be simply 4 switches not 4 transistors u will understand this after reading bout the H bridge of course
now to have a variable speed i only know one way to get that and its using the PWM(pulse width modulation)
and that can only be done using a microcontroller
best regards
 

KlausST

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Hi,

It mainly depends on the motor.
Washing machine motors often are AC motors. Especially the older ones have many connections for various speeds and direction.
Try to search the internet for the schematic of the motor or the washing machine - if you know vendor and type..


Klaus
 

BrunoARG

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Hello.

I think that the rotation direction might be controlled by hand, using a lever or a switch since mechanical lathes are turned on and off manually (including the rotation direction) could be a good idea.

The speed control could be carried on using a AC dimmer. If the AC motor is a single fase one, thing I think is true because washing machines are designed for a single phase voltage line, you can control its speed with a really simple circuit.

Just search "ac motor dimmer" on any search engine and you'll find a lot of circuits; take into account that as an inductive load is being used a properly capacitive compensation should be calculated and used. There exist several C-L phi cosinus compensation calculators, maybe the motor has connected (and should have) its compensation capacitor, if not, look for it at the PCB and unsolder it or buy an equal one.

Just ask if you didn't understand anything.
 

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