2
Recommendations:
- Never apply a voltage higher than +15V
or lower than -15V to the amplifier input to
prevent damage.
- A short voltage spike may appear at the
output, when the amplifier is turned on or
off. Pay attention not to damage sensitive
circuitry or equipment already connected.
- The amplifier cannot be damaged by a
short-circuit
condition
or
capacitive
loading, but avoid:
● Connecting a charged capacitor to
the input or output.
● Connecting a highly inductive load to
the output (such as a coil).
- Do not connect anything to the output
that can act as an antenna.
- Use the amplifier within its specified 15 -
30°C ambient operating temperature
range.
- Unplug the WMA-100A amplifier from the
mains power before cleaning. Only clean
this product with a soft, slightly moist cloth.
Safety
- This product is able to produce over
170V at more than 100mA at its output,
which is a very high level (risk of electric
shock). Safety measures should be taken
accordingly. This is indicated by the sign
above the output connector.
- This product is a Class I appliance which
requires a mains connection with
protective earth.
- Always position the WMA-100A amplifier
such that the on/off power switch is easily
accessible.
- The airflow to and from the WMA-100A
amplifier should not be blocked or
impeded at the front, sides and rear panel.
- The internal circuitry of the amplifier
operates at high voltage. Only qualified
personnel from Falco Systems should
service this amplifier.
- Use the 230V and 115V versions of the
WMA-100A amplifiers with their intended
mains voltages only.
- Only replace fuses with the correct type:
● 230V version of the WMA-100A: 250V
250mA 5x20mm slow blow.
● 115V version of the WMA-100A: 250V
500mA 5x20mm slow blow.
- The Falco Systems WMA-100A amplifier
is only suitable for indoor use in a class II
environment (domestic, light industrial).
- Non-sinusoidal mains power generators
cannot be used to power this product.
Detailed properties of the
WMA-100A high voltage
amplifier
Input
The input impedance of the WMA-100A
high voltage amplifier is a 100kΩ resistor
to ground, in parallel with 68pF to prevent
electrostatic
discharge
(ESD)
input
damage. This resistor adds some noise to
the output voltage unless a low-impedance
source (e.g. a 50Ω output function
generator) is connected to the input. The
noise will be slightly higher when the
amplifier input is left open.
The 100kΩ resistor adds to the output
offset voltage because the offset current of
the input amplifier generates a voltage
over this resistor. Driving the amplifier with
a low impedance source will prevent this.
A high-speed amplifier like the WMA-100A
model can never be made fully insensitive
to input overload conditions, as this would
limit the performance of the amplifier
significantly. For normal operation, input
voltages should remain in the -8.5V to
+8.5V range. This will result (with an
amplification of 20x) in an output voltage
swing of -170V to +170V.
Below -15V and above +15V, the input
protection circuitry will limit the voltage
being fed to the amplifier. In this case, the
amplifier may be permanently damaged if
the current of the source is not limited.
Output
The WMA-100A amplifier has been
designed to be fully stable with all
capacitive loads. It has been optimized for
a perfect step-response, but it is also a
very good linear and sine-wave amplifier.
The WMA-100A model has a clever
feedback system, which ensures that no
significant overshoot occurs at any
capacitive load. The bandwidth of the
amplifier is automatically reduced to
ensure stability. Instability under capacitive
loading conditions is a common problem of
high-speed negative feedback amplifiers,
often resulting in unwanted output
overshoot voltages, and, in extreme
cases, oscillations.
