Application Note

3 Fluke Corporation On the rivers of Suriname, electric eels reveal their secrets
While the Electric Eel relaxes in its wading pool, Prof. Will Crampton prepares the Fluke ScopeMeter to test the most
powerful electric fish. Courtesy of Windfall Films, Ltd.
How the eel measures up
With the eel safely cor-
ralled in an inflatable holding
pool, Crampton and the crew
deployed their ScopeMeter
190-202 to measure the ani-
mal’s output. Thought it wasn’t
designed for biometrics in the
rain and humidity of the Suri-
name jungle, the instrument’s
durability and compact design
proved ideal. Its batteries pro-
vided ample power for days in
the field.
“You can knock it around a
bit and not be worried about it
malfunctioning,” Crampton said.
“I didn’t test whether it was
completely waterproof, but it
drizzled with rain at one point
and I didn’t bother to cover it up.
It was fine.
“The Fluke very clearly
showed the wave forms,”
Crampton said. Next came a
demonstration using an array of
LED lights and capacitors created
by Jeff Lambert, electrical engi-
neer in the Crampton laboratory.
“We couldn’t test it—we don’t
have any electric eels in the
lab,” he said. “It’s illegal to have
electric eels in Florida, except
with a permit. They would do
very well here.” As if on cue, the
eel in Suriname lit up the LEDs.
“The finale was to measure
voltage,” he continued. “You
have to isolate the electric eel
from any load on its electric
circuit. That’s done by placing
it on a dry plastic sheet. We set
up the ScopeMeter so that we
had an electrode on the eel’s
head and a ground on its tail.
This was an eel that was a half
a meter long, and I believe the
voltage that came up on the
screen was 498 volts. The cur-
rent was about one ampere.”
Crampton appreciated the
flexibility of the Fluke portable
oscilloscope. “With the Fluke
190-202 there’s a nice opportu-
nity,” he said. “You can capture
signals at very high sample rates
and pretty good bit resolution
just by going straight in—you
don’t have to amplify either the
weak or the strong discharges. I
was able to get recordings of the
weak discharges when the elec-
tric eel was in the water, and
to get the strong discharges we
had it out on the plastic sheet,
and I would just tap it lightly on
the head to annoy it, and that
would be enough to generate
the strong discharge.”