Change motor polarity each time power is connected???

[itsallgood]

Hi guys,

Is it possible to make a motor change direction when the power is connected -- change the polarity each time the power is connected.


If it's turning clockwise - and I cut power, and reconnect -- I want the motor to then run anti-clockwise.


Would this need a microcontroller to remember the last state - or is there an easier way?


Thanks so much!

 

[BradtheRad]

My microwave oven has a carousel. I have seen it go in one direction one time, then the reverse direction next time.

So yes, it is possible although I don't know just how to do it.

It will require some memory storage device (electronic or mechanical). For instance a flip-flop, although that will only work if you can keep power connected to it.

If you must disconnect power then you might consider a capacitor or supercapacitor. However they will eventually discharge.

There is also the switch on a ceiling fan, to control motor direction. It should be possible to duplicate this electronically.

 

[betwixt]

The microwave oven motor direction will be random, it depends on whether it catches the rising or falling side of the AC power at the time it is switched on.

'Itsallgood', what kind of motor are you thinking of? The technologies for driving and reversing a motor depend on it's type. In general though, if you want it to reverse reliably at each power-up, you will need some kind of memory to remind it which way it previously turned. An electronic memory is the obvious choice but you may be able to use a latching (bistable) relay instead.

Brian.

 

[ark5230]

A small battery powered latch or flip-flop may be considered.
If battery is to be avoided, fan switches using pulling of string could also be simple.
Every time it is powered, it will throw switch in the opposite direction.