Wednesday, December 29, 2010

current, power, energy

Since my last post, I have repaired the part I thought I'd ruined, and have made further progress on the Mad Scientist Light Switch. Nothing worth showing you just yet however.

I've also inched forward a bit in work toward commissioning tests of my triggered spark gap switch.  One of the things I'll need to test and characterize it is a series of dummy loads of various values, all very low inductance, and capable of absorbing around 3kJ in a short pulse.

The resistors I can either make, or in some cases like that shown here, I may get lucky and find something commercial that will serve.

To use any such resistors, I've got to have a way to connect them to the switch, and the switch to the capacitor and so forth.  The connections will have to pass a series of increasingly high current test shots, stepping up by orders of magnitude.  Here's my first pass at a basic high current, low-inductance connector for the resistor:

The scale is 12 inches / ≈ 30.5 cm long.

I ought to find myself some thicker copper pipe. This stuff is 'schedule L' pipe, with a nominal bore of 1.025". Note how the pipe is bent inward by the clamps to meet the 1.00" OD of the resistor terminals.

There is a thicker series of copper pipe - 'schedule K' - which has a nominal bore of .995".  It should mate more smoothly than the L, and if necessary, I can turn out the ID a few thousandths and still have a thicker wall.

Four more slits need to be made in the outer ends of the copper pipe, so as to receive brass inserts which will connect to the switch at one end, and the outer return casing at the other end, subject to my whims and availability of parts.

The switch housing requires 5" ID copper DWV pipe which is available but annoyingly expensive.  I need a short piece for this rig, and a long piece (5 or 6 feet) for the big Marx generator.

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