Safely discharging a capacitor

Why do you say that? Most European washing machines use series wound universal motors with carbon brushes. I've got a Creda washer sitting in my basement right now awaiting arrival of a set of brushes amoung other things, no idea how it ended up on this side of the pond but it's a cool little machine.

They went over the top years ago, those capacitors have been available for a while.

Just try to find a car CD player anymore that looks at home in anything but a gaudy racer boy Japenese compact. Seems like they're all fugly and bubbly, loaded with useless distracting blinky lights and buttons so small and jumbled it's impossible to operate them safely while driving.

While this is true, don't forget that the starter motor will never be operating under load while the alternator is producing any current unless you're jump starting another car.

But we were talking about a dryer. They seem to use induction motors (well, mine does).

But its NOT a washing machine he's fixing ! its a tumble drier

All the ones I have ever seen are, because they revolve the drum slowly, a washing machine needs to spin at high speed

Thats because youy get a really good one bult nto any car that chavs don't buy.

A European washing machine operates its motor at a large number of different speeds (and even gradually vary the speed in some cases) throughout various stages of the wash cycle, and depending on the wash program selected. This is most easily done with a universal motor combined with an electronic speed control board and servo feedback. (It used to be done with an induction motor and solenoid operated gearbox 40 years ago, but that's more expensive and a lot less flexible.)

Tumble driers only have to be able to reverse the drum, but don't need to change the speed. For this simpler requirement, an induction motor tends to win.

its nowhere as bad as what a statrter motor does...alternators are limited anyway.

Yeah somehow I missed that we were discussing a dryer. The matching Creda dryer does in fact have an induction motor in it, weird to see a clothes dryer that will plug into a 15A 240v receptacle, US dryers are almost universally 4KW.

Why do they have to be able to reverse the drum? I've never seen a dryer that did that, obviously they must exist but I'm not sure of the benefits.

Would be nice, but I'm afraid back in '84, '87 and '88 respectively, cars didn't come with CD players of any sort, hence my need to install aftermarket units in mine.

Not to mention I'm still not aware of any OEM units that will play MP3 discs, an essential feature to me that made all earlier CD players virtually obsolete. 10 hours of music on one disc, no more fumbling with CD's in traffic.

Loads of them do it[1]...helps to untangle the clothes.

In message , paulfoel writes

It depends what's across it,

stick a screwdriver across it - that'll discharge it

In message , Slurp writes

Where does one start, any site that had the following in the disclaimer

'DISCLAIMER: the experiments described below are fantastically dangerous, and they are described without reference to the many precautions needed to guarantee the experimenter's safety. Accidentally discharging these capacitor banks through your body can not only kill, but can explode flesh and bone.'

Followed by

'PARENTS: I supply no detailed plans for reproducing these experiments. Also, these experiments require large and expensive lab equipment which is not obtainable by children. (And the plans for an atomic bomb are safe for children too, because kids can't afford to buy kilograms of Plutonium!) If your kids have access to 5,000 volt high-current power supplies, then they are already in great danger, whether or not they read about my capacitor discharge experiments below.'

Has my respect!

In message , snipped-for-privacy@hotmail.com writes

STOP IT STOP IT STOP IT

You're giving me ideas

According to my Electrical Engineering professor at university *all* electrical machines (including transoformers) are really induction motors.

Motors with squirrel-cage rotors can be used on single-phase alternating current by means of various arrangements of inductance and capacitance that alter the characteristics of the single-phase voltage and make it resemble a two-phase voltage. Such motors are called split-phase motors or condenser motors (or capacitor motors), depending on the arrangement used. Single-phase squirrel-cage motors do not have a large starting torque, and for applications where such torque is required, repulsion-induction motors are used. A repulsion-induction motor may be of the split-phase or condenser type, but has a manual or automatic switch that allows current to flow between brushes on the commutator when the motor is starting, and short-circuits all commutator segments after the motor reaches a critical speed. Repulsion-induction motors are so named because their starting torque depends on the repulsion between the rotor and the stator, and their torque while running depends on induction. Series-wound motors with commutators, which will operate on direct or alternating current, are called universal motors. They are usually made only in small sizes and are commonly used in household appliances.

"Andy Dingley" bravely wrote to "All" (21 Dec 05 14:16:40) --- on the heady topic of "Re: Safely discharging a capacitor"

AD> From: Andy Dingley AD> Xref: core-easynews sci.electronics.repair:352066 AD> free.uk.diy.home:47734 uk.d-i-y:545608

AD> >Assuming it is still ' live' how do I discharge it to make it safe?

AD> Stick a big screwdriver across it.

Now why ruin a perfectly good screwdriver?! You should see mine, it's full of big burned out pits from starting up cars at the solenoid. Mind that disharging those 50 volt 100,000uF audio amp supply caps is a little more hazardous than say a 6.8uF AC motor start cap. (grains of salt ->...)

A*s*i*m*o*v

... You may be a tech if you're entertained by a 6-pack and sparking HV.