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That's not a Filbert Flange, that's a Fleistine Fillet!

The idea is that the short will be routed back via the metallic ground' conductor.  Even a substantial current can't develop a lot of voltage across that very-low-resistance connection, so unless you are drenched with water, your own resistance will divert 99.99% of the current through the ground, and that current will be sufficient to blow a fuse or pop a circuit breaker.

The downside is that if you're holding a grounded tool and you get hooked up to another current source, the circuit to ground goes straight through you, with many bad effects.  Ground-fault circuit interrupters guard against this, but they need to be tested.  They do fail, and they generally leave their outputs energized when they do.  You need to check them if you mean to trust them.

Some years ago, double-insulated tools were available.  They keep you out of the circuit altogether, which strikes my engineering mind as the better solution.  I don't know whether they were de-listed or just forgotten.  It's worth noting that one essential tool for a TV repairman was an isolation transformer that would deliberately disconnect the chassis from electrical ground while providing AC power, so that if the repairman accidentally came in contact with high voltage somewhere, there would be no circuit to complete.  I'm not sure how much it would help if the voltage was the picture tube accelerating voltage, which ran from 40,000 volts to 120,000 volts in various TV models.  (The accelerating voltage was actually produced as a by-product of the horizontal sweep, which had to snap back at the end of each scan.  A circuit configuration called a blocking oscillator provided the sawtooth wave and the charge reservoir for the accelerating voltage provided a place to dump the energy when that 'flyback' was arrested.)

Amy ... I have a few more things to mention on Honor.  I'll do it as soon as I'm finished here.

Norm D ... Grounding and electricity:

There's a whole layer cake of theory on grounding, and I don't have the expertise to go many layers up.  But then, you'd have a hard time following.

So ... some basics about electricity.

The basic unit of electricity is the electric charge.  Negative charge is carried by electrons, which move easily through conductors.  Positive charge is in the nuclei of the atoms, which are fixed in place in solid conductors.  In liquids, they are still hard to move because they are millions of times heavier than electrons.

Charge is measured in Coulombs, each Coulumb being about 6.24x10^18 electron charges.
Electric current is charge in motion: an Ampere is the movement of one Coulomb per second though a notional surface.  (An electric current creates a magnetic field around it.)

Electric fields (electric potential) extend from positive to negative charges; positive and negative charges attract each other, and if allowed, current will flow 'from positive to negative', which means electrons move toward the positive charge.

Now ... how much voltage (potential) does it take to propel that current from one point to another?  In the simplest case, current flows in proportion to voltage, and that proportion is called conductance.  We usually talk of conductance by its numerical inverse, resistance (ratio of voltage to current).  The amount of resistance follows from the bulk properties of the materials involved (silver has a very low bulk resistance or resistivity; fused quartz has a resistivity 10^17th higher) and from the geometry (multiply by length, divide by cross-section area).

What this means is that even a poor conductor like the earth beneath us can act as a good conductor if we get a good cross-section--and there's a lot of earth to get that cross-section.

And  ... how much charge do you need to pile up to create a potential of one volt?  That depends on two things: the geometry of where you're piling up the charge, and the bulk properties of the materials that the electric fields penetrate.  (The bulk property is called permittance, and the proportion of charge to voltage is called capacitance.)

The earth is a big object, and you can pile up a lot of charge in it without much changing its electrical potential relative to anything.   (Electrical potentials are always relative to each other or to something.)

So in concept, electrical earth (or 'ground' as we Yanks say) is a reference point that can absorb or provide infinite current with no change in voltage.

Of course, nothing's perfect.  Still, if you get an accidental connection to a 120 or 240 volt power line, a good connection to ground can divert enough current to pop a circuit breaker.  (And Ground Fault Interruptors detect ANY leakage to ground, by looking for a difference between the incoming and outgoing currents.)

The 'ground' potential from one part of a building can differ from another by several volts, for a variety of reasons.  This can cause havoc with the old coaxial-cable ethernets, which is why the more recently designed twisted-pair networks are transformer-coupled at both ends.

Within an electronic circuit, 'ground' is a place in the circuit network that serves as a reference point for (almost) every voltage and a current sink for nearly every power supply element.   There are different symbols for circuit ground and 'chassis' ground, though they may in fact be the same.

Resistivity is a bulk property of a material and is unaffected by any but the highest frequencies.  Capacitance is more interesting.  Every bit of geometry in the layout of a circuit introduces capacitance.  At frequencies below ten megaHertz or so, only the devices built as capacitors have gross effects; the effects of stray capacitance are generally small.  (But not always; the product of capacitance and resistance determines the frequency at which effects begin.)

Analagous to and inverse to capacitance is the property called inductance.  It follows from energy stored in the magnetic field induced by a current and acts like inertia on the flowing current.  (The stored energy depends on the amount of current, the geometry, and the properties of the materials which the magnetic fields penetrate.)  Where capitance means that voltage grows over time with current, inductance means that current grows over time with voltage.  (Resistance divided by inductance tells you the frequency at which inductive effects become significant; in both cases the 'time constant' is one over the angular frequency, and the angular frequency is two-pi times the cyclic frequency.)

Which is more than you ever want to know, but it gives another important use for grounded conductors in circuits.  A 'ground plane' can keep the elecric and magnetic fields generated in one part of a circuit from influencing those in another.  And, in a behavior called 'a transmission line', it can help a high-frequency signal move through an adjacent conductor in an orderly way.  (Transmission lines lie between the behavior of ordinary circuits and the behavior of radio waves.)

Now that's =way= too much information!

Well, I have tinkered with the head amp to make it more resistant to changes in battery voltage.  (The output drops about 2 dB when the voltage drops by 1.6 volts.)  I'm going to have to play fast and loose with the circuit board to fit it all.

And then I have to -try- it to see how much noise the thing introduces.

Wednesday I try to find someone to take books with a hope of selling them.

So I gather that my blue-pen prejudices were of some use?

Which reminds me, I used actual blue ink -- Diamine Havasu Turquoise -- to mark up the copy and I need to refill the pen.  I have to buy ink soon, too.  (Not that one.)

edit: So when does the new model come out for show?

And when I have the head-amp done, I'll need to go through my resistor stocks and see what I need to order.  There are 24 "preferred number" values per decade (see Wiki-P, E24), and eleven plus decades of interest, with some values missing on the ends.  (Plus different sizes for 1/8, 1/4, 1/2, 1, and 2 watt dissipation.)  Most resistors are cheap in quantity 10 or 25, but the sheer number to stock adds up the cost.

(I also need to order some 100uF tantalums.  I thought sure I had some around here.)

It's not there.  You have to chase links from Amy's portfolio, or from your last review of it.

I'm not hungry for points (I don't know about KH) but if you want to encourage new reviewers you should probably repub.

Oh, for those who argue for more dialogue and less summary, I point you to Poe's Hop-Frog.  See how much of the dialogue is summarized, and to what effect.

My housing crisis is turning into a chronic clean-up, which means things will be a mess for a long time.  I've gotten a few dollars for about forty pounds of books, and I'll always second-guess myself on what I let go.  I probably need to clear out another four to ten shelf-feet of papaerbacks (besides those I'm shopping around now), but I may not be able to find buyers for them.

Okay, so now I'm trying to get back to business.  In the next two or three days I want to start to catch up on reviewing, and to start writing again.  It may take me some time to pick up where I left off.

Meanwhile, I'm having my electronic design skills challenged.  See users.ece.gatech.edu/mleach/headamp , first design (dual-ended common-base amp, no current mirrors).  A very nice design, but a long start-up (settling) time because of the extraordinarily low-frequency limit on its input side.  The output side's low-frequency limit appears to be a decade higher (but still below  the stock 20 Hz).  And the floating battery means that powering two of them off a common supply requires some trickery.  (The article tells of a manufacturer who did it with an incandescent lamp and photovoltaic cells--the sort of exotic excess that Truly Impresses audiophiles.)

Adrenaline tends to overcome both pain and injury, with a high price to be paid later.  But if Catherine is worried and doubting the injury will overcome her sooner.

Can she be lashed to her horse?

Just stay a safe distance from K ...