bandpass with a gain of one to
remove any noise that might be
picked up by the probe. IC2 also has
a gain of 100 for a total of 10,000;
the signal is inverted to reduce the
chance of oscillation, but even so,
careful layout and shielding will be
The final stage is a full wave
rectifier and filter to give a DC output
proportional to the sheet resistance.
The LMV751 has a max supply
voltage rating of 5V. I want to
continue with plus and minus
supplies, so I reduced the supply to
±2V using green LEDs.
I have been thinking about the
static field meter and can’t find
anything online about how it works.
Early experiments measured the force
exerted by charged objects, but I
don’t see that as a way to measure
the field in practice. It is not possible
to take power out of a static field (or
it will not be static), so I don’t know
how to do it. Field-effect transistors
operate on voltage, but 10,000 volts
would zap it instantly.
Perhaps a voltage divider using
capacitors would work but charging a
capacitor requires current, and the
leakage current of the transistor
would charge the capacitor. So, that
won’t work. Two foils will separate
when charged due to electric
repulsion, but I don’t know how to
implement that. Does anyone have
QI’m back and I have better news, I think. First, I would like to say thank you. I have njoyed reading about my
project in your June and July 2013
I read a lot of articles written
about coil drivers and Jacob’s
Ladders, and picked up a couple of
ideas I thought might help me.
I pretty much just copied stuff
from other schematics I found on
18 September 2013
■ FIGURE 3.