Electronics Forum / Electrical Engineering / November 2003

this is a test of outlook

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A thermos flask with a heating element that is powered by
electricity run from an electrical generator. A mechanical spring
could be encorporated in the design as well.
When someone's body core temperature is low the best way

Can someone help me with the type of equations i can expect on the master
electrician's exam?

I find it pretty hard to find a shop that actually understands what
one is asking for... I my case most of the shops I called up they did
not even know the amplification class of their transistors in stock
(not to mention the voltage selection I need, or anything about

I need to power a relay from 120 vac such that its action is delayed for a
few seconds after power-on. I realize that this means getting DC voltage (via
diode) and an R-C combination.
Ideally, a relay with DC-rated coil would be most appropriate, but I've got a

I have noticed that the insulators on the HV pilons are installed in one of
two ways:
a) Vertically. One insulator stack is holding up the wire weight.
b) Horizontally.  Two insulator stacks are holding agains the wire tension.

Every outlet I have ever seen in older homes (1910-1930) has only two
wirea in the box, they can't all be 'end of run'. Was this common
practice back then? It doesn't seem like an efficient use of wiring.
So what's going on within the walls? Are there main wires to which all

I have one of those RF "breaker finder" gadgets that I've used with good
success. It's a basic no-frills type that
doesn't trace open circuits or anything. I was doing some electrical work at
a friends' house where I wanted to turn off a breaker to a branch circuit

An example would be for a panic alarm system in homes which
would work even when a phone system is down or not installed.

I'm dealing with IEC 1000-4-6 standard (Immunity to conducted
disturbances, induced by radio-frequency fields), and I'm having some
difficulties in applying it.
Does anyone have some kind of tutorial, application note, web pages,

https://reports.energy.gov/
I'm not an electrical engineeer, but, makes interesting reading.

I recently had to replace the pump on my washing machine as the old
pump was randomly failing to start. On examining the old pump I can find
nothing wrong with the impeller mechanism, which leads me to believe its
probably the small capacitor (used for starting the pump? - it has no

Can anyone help me? I am building a machine at the moment and I am
stuck on a bit of it. I need a switch that I can use to reverse the
mains input. I don't want anything too huge and heavy duty but I am
aware that a simple rocker switch wouldn't work as I need a clean

I have an air handler for heating and cooling. When the air was added the
installer noted that it was close on the CFMs. Now I find the unit has to
run much longer to maintain temperature settings. I suspect that my air
flow is reduced by the air coil. While oiling the motor of the ...