vacuum cleaner motor reversal?

Does that make us a sad pair for finding out? :-)

All I've had have rotated each time in the opposite direction to the previous run. Bar one, which didn't have a turntable, but stirred the waves instead.

Thanks to all who replied, but it looks like a non-starter....I may just take the motors out and make something completely different, but knowing me, they'll stay on the shelf in the shed gathering dust until the day I pop my clogs, when one of my relatives will probably say, 'he was going to do something with those but never got around to it'.

I'd never noticed that until somebody (Huge?) mentioned it a while back. I had noticed it vary in direction, but assumed it was more or less random.

Not that I'm a great user of tinywobblers...

Clearly I've lead a sheltered life. ;-) Of course we have been using the same Toshiba microwave for over 20 years (that's been nicked once and dropped on a building site) so I suppose I shouldn't extrapolate from my experience.

Anyone using an older microwave?

Tim

In message , Tim Downie writes

I prolly am, mine must be a good 25 years old, still works well, the only thing I have had to change was the capacitor in the HT (Which got donated by someone here in UK.d-i-y about 7 years ago)

Mine reverses direction every time it starts

Only recently replaced a Sharp which was bought in 1982.

Our old one always went round the same way. Our new one goes in alternate directions.

Slip isn't just phase lag, it's a slower speed too. Otherwise you've built a perpetual motion machine!

Truly synchronous motors have slip when they start from zero speed, but must have zero slip when running. This does make them more complicated to manufacture, as they generally require some separate starting device. OTOH, a simple fan motor can use a slug (a shorted turn of thick copper around half the winding, inductively producing a phase lag).

Practice for clocks was often to use manual start buttons. In the GPO ("Class B" clocks?) this "bug" was documented as a "feature". As the clocks weren't self-starting after a power outage, they would be obviously stopped rather than just set slow.

Er, no you wouldn't!

They can never have zero phase lag (slip) when running or they wouldn't turn. The lag causes the force (which constantly tries to get them back in phase) that causes them to turn. If they were turning with zero phase lag you might have a perpetual motion machine! This phase lag is naturally there becasue of the load (at minimum just bearing friction) on the rotor. The trouble is at rest, when there is no net phase lag in either direction and therefore no force. Thus an artificial one has to be applied to ensure starting [in the right direction].

They certainly lag by phase, but slip (outside of a 100% efficient motor) is a reduction in _speed_, not just an equal speed lagging by constant phase.

Also a 1987 Toshiba. The turntable starts in either direction but does not auto-reverse at any time.

Geo

You're right, of course. I was thinking of fitting a computer fan the other way round - but of course they're in one with the motor.

Indeed.

Many years ago, parents had an Electrolux cylinder cleaner. That had a connector under the filter/outlet air vent - you could connect the hose to that. IIRC they actually sold something like a spray gun that was intended to work like that.

you can give try to dyson vacuums, they are very sturdy, rugged and robust. easy to handle and low power consumption.

That is correct, we had one branded Vactric like this. You just took the filter off the back end and you had a screw thread you could attach things too. Its not done these days, for whatever reason. Most are crammed full of filters which get clogged up and need a good wash or replacing every so often. Brian

Reversing the direction of spin of a centrifugal impeller will not reverse its function. It may just reduce its efficiency.