97042 Rev A 11/21 Page 8 of 16
can be achieved using a coin in the slots of the knob.
1.2.4 Input connector: Single-ended BNC and Balanced XLR and TRS connections are available and
can be selected using the Input Select switch on the rear panel of the amplifier. It is recommended to
use the BNC single-ended input. The balanced input requires a balanced pre-amplifier source.
1.2.5External/local switch: To power-up the amplifier using an external control voltage, supply a 5V
to 12V AC or DC control voltage to the ‘IN’ terminals of the control voltage connector. Use paired wire
of 22 to 18 gauge between the source device and the WST7B3amplifier. By selecting the switch to the
“external” position, the amplifier will power-up only when the control voltage is present (on). Immediately
following power up, the control voltage will appear at the ’OUT’ terminals of the control voltage
connector for the control of other equipment. The removal of the control voltage (0V) causes the
amplifier to turn ‘off’ and the control voltage at the ‘OUT’ terminals will be interrupted. In the “Local”
setting, the amplifier will ignore the control voltage and power up only by using the front panel push-
button power switch. If a control voltage is present at the ‘IN’ terminals, it will still be available at the
‘OUT’ terminals after the power-up sequence.
Notes: The “OUT”terminals are connect to the “IN”terminals once the amplifier has powered-up. The
control current is determined by the source equipment. The carrying current of the “OUT”relay is 2
Amps. The amplifier’s control circuitry itself draws less than 2mA from the control current when
operating.
2.0 Operation of the power amplifier
Wilcoxon Sensing Technologies manufactures a comprehensive line of vibration generating systems,
including electromagnetic and piezoelectric shakers. Electromagnetic shakers are powered directly
from the output of the power amplifier. However, piezoelectric shakers require a matching network
between the power amplifier and the shaker. A signal source to drive the power amplifier is not part of
the system and must be supplied by the user. This guide describes the operation of the WST7B3power
amplifier. Other guides describe the operation of the matching networks and shakers. For all vibration