Going to attempt to change the capacitor on my tumble dryer... Its a 8
I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?
Assuming it is still ' live' how do I discharge it to make it safe?
Most likely it is discharged through the motor windings unless
the switching is such that it gets disconnected, although
relying on the motor windings being intact is not smart when
the thing is known not to be working properly. Secondly, it
probably has a bleed resistor built in, although those can
fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.
I was in the local Maplin shop the other day and saw that you can purchase 1
farad (huge) capacitors for power supply smoothing chav's in car audio
Must be interesting when you accidently short one of these!
I've got this terrible urge to dig out some perspex
sheet I've got left over in the garage...
I built a Van de graff generator when I was at school,
but that was rather disappointing. (On later reflection,
I'm not sure the belt material I used was a good enough
Then I built a high voltage generator using a car ignition
coil, EHT valve rectifier, and a capacitor made from
kitchen foil and a large roll of cellulose acetate
overhead projector film. I got really 'cracking' 4"-5"
sparks from it for a day, until the cellulose acetate
'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.'
'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!
A capacitor with a digital readout? Now they've gone over the top! :)
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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.
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.
Car wiring is radial from the battery to alternator and from the battery
to load. The impedance of the battery is much lower than that of the
alternator radial circuit - thus transient currents will be met almost
entirely by the battery.
You may like to think what effect the starter motor has on the alternator.
Also, the energy stored in a capacitor depends on the capacitance and on
the square of the voltage. Rather than have a 1F capacitor on the 12v
line, it would be much better to go to the higher voltage power rails of
the amplifier and stick beefy capacitors there.
Does the motor have brushes and a commutator? If so, change the brushes
before you start looking elsewhere, they're seldom expensive and are a
consumable item. Capacitors may or may not last the life of an appliance but
brushes are certain to wear from day one and are usually the first suspect
in a misfiring/intermittant motor.
With brush type motors, the brushes wear down and consequently less pressure
is applied by the spring, causing a higher resistance/poorer connection
between brush and commutator. An arc is caused, which heats the brush and
can deform the casing causing the brush to stick, making the problem
increase exponentially. It also causes the commutator to become blackened
which makes matters even worse.
I'd take out the brush carriers and check the brushes move freely and that
there's plenty of length left on them. Also check the commutator is clean.
If the motor does not have a brush/commutator arrangement, I'd check all
connections are secure and check the control board for dry/cracked solder
joints before suspecting component failure.
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