Isolated Stimulator; The Bio Amp Inputs (Inputs 3 And 4) - ADInstruments POWERLAB TEACHING SERIES Owner's Manual

Isolated Stimulator

The PowerLab 15T and 26T have a built-in, isolated, constant-current pulse stimulator
that can be used for any general-purpose stimulation with humans. The Isolated
Stimulator section of the front panel has two output sockets, two indicator lights and a
safety switch. Note that you cannot use the analog output and the isolated stimulator at
the same time.
The stimulus output is supplied via two 4 mm shrouded banana sockets; the left -hand
(red) socket is positive, the right-hand (black) socket is negative. These are designed for
use with shrouded male 4 mm plugs (the shrouding is to prevent accidental stimulation
while fitting or removing the plugs). The bar stimulus electrode supplied with the
PowerLab uses such plugs.
The output is capable of supplying 100 V pulses at currents up to 20 mA, so it should be
treated with caution. The Isolated Stimulator Pulse indicator is an LED that indicates
the current status of the Stimulator. It will flash green for every stimulus pulse, and
may seem to glow green constantly at higher stimulus frequencies. The OOC (out-of-
compliance) indicator is a yellow LED. When lit, it indicates that the output is overloaded
or out of compliance (compliance is the ability to supply voltage to meet the required
current). This means that the impedance of the tissue being stimulated is too high, or
there is a poor electrical connection (possibly due to electrode drying), and that the
Isolated Stimulator can no longer supply constant current stimulation. If this should
happen, try reducing the output current amplitude, and check all connections.
To provide an additional level of safety, a safety switch is located on the front panel
to allow the output to be switched on and off as needed. The switch should be flicked
down to turn the output off : doing so disconnects the output sockets from the internal
circuitry, allowing connections to be made safely while the PowerLab is on.

The Bio Amp Inputs (Inputs 3 and 4)

The PowerLab 15T and 26T have a connector for two Bio Amp inputs, marked Bio Amp
Input 3 & 4. These biological amplifiers perform electrically isolated measurements of
biological signals, such as electrocardiograms (ECG) and electromyograms (EMG). The
two Bio Amp inputs have a common six-pin connector with a shared ground signal and
are internally configured to use channels 3 and 4 of the PowerLab.
The PowerLab comes supplied with a 5-lead Bio Amp cable and lead wires. The Bio Amp
inputs should only be used with the supplied Bio Amp cable and approved leads. Other
cables may not meet safety requirements. Note: with the PowerLab 26T, connecting
an ADInstruments pod or smart transducer to either analog input 3 or 4 turns off the
corresponding Bio Amp input.
PowerLab Teaching Series - Owner's Guide
12