JazzMan wrote:
I've got a new camcorder, the old Cannon bit the dust.
Unfortunately the 6V gel-cell battery that I used to
power it won't power my new camcorder because that one
needs 8.4V. So, what I need (I think) is a DC-DC converter
that takes down to 5.5V and bumps it up to a nice clean
8.4VDC @ 1A (the rating on the A/C adapter that came with
the camera). Is this something that's possible?

Next up, I want to build a nice NiMH charging circuit
that uses temperature to control the charging cycle. I know
it's a bit more complicated than that, but does anyone have
some good sources I can start learning at? I've been using
the cheap timer chargers but I find that typically the AA
cells are too damaged to be reliable after only 10-20 chargning
cycles.

Next one's more difficult, I think. I want to make some
exhaust temperature pyrometers. I bought some thermocouple
wire, and want to use stainless steel tubing to make the
actual probe with. I'll weld one end of a short length of
tube closed with my TIG, and I'll use a compression fitting
with a 1/16" NPT pipe to actually install the probe into the
exaust tube at the head. Do I need to weld the ends of the
thermocouple wire together to establish a junction? Or will
twisting the ends together work? Also, I'd like to pot it in
something to electrically insulate the wire from the housing,
what can I use? I'll be making half a dozen of these so that
I can do cylinder to cylinder comparisons.

Any suggestions, sources, and/or ideas would ge greatly
appreciated!

JazzMan
--

In your application I'd suggest welding.

There's nothing wrong with twisting the wires together from a
theoretical point of view but in practical application twisting might
not work. Oxidation or vibration could lead to loss of electrical
continuity. Plus a twisted junction tends to be worse in terms of
thermal properties with too much mass and length that can add errors to
your measurement. Also cold working some thermoelements shifts their
calibration.

Bill