Falco Systems WMA-005 User manual

USER MANUAL
● High voltage: 20x amplification up to +75V and -75V output voltage
● DC to 20kHz large signal bandwidth and 50kΩ output resistance
● Power supply 24V DC, battery powered operation possible
● No overshoot with capacitive loads: bandwidth changes automatically
to ensure stability
● Short-circuit protected output
About this manual
This user manual is an integral part of the
Falco Systems WMA-005 and WMA-
005LF high voltage amplifier products.
Please read it carefully and pay attention
to the recommendations and instructions
for safe use.
The WMA-005 high voltage
amplifier: general description
The Falco Systems WMA-005 and WMA-
005LF are high voltage amplifiers that run
from an 24V DC power supply and can be
battery powered if required, e.g. for use in
a Faraday cage. Its internal high voltage
generator is inductor-free and hence does
not spread magnetic interference in
sensitive experimental setups. Its large
voltage range makes it an excellent choice
for use with MEMS devices, EO-
modulators, piezo actuator positioning
systems, beam steering components, and
many more.
The amplifiers’ full-power frequency
response has a -3dB corner frequency at
20kHz. The input impedance is 100kΩ and
the output 50kΩ.
The output noise of the WMA-005 is
<3mVrms. For extremely low noise
applications where bandwidth is not an
issue, the dedicated WMA-005LF version
is available. This amplifier contains an
output low pass filter capacitor which
reduces the bandwidth to 50Hz, but makes
the noise drop to 0.1mVrms. This
bandwidth-limited amplifier is ideal for
MEMS or piezo positioning with manual
voltage adjustment requiring extremely low
noise.
Falco Systems WMA-005 High Voltage Amplifier DC – 20kHz

!
2!
The WMA-005 and 005LF amplifiers
contain an over-voltage protection for daily
use in the laboratory and are long-term
short-circuit proof. The input (indicated
“Input” on the label), output (indicated
“Output”) and DC power supply (Indicated
“24V DC 180mA”) connections are all
standard BNC.
The amplification is 20x (fixed). The
amplifiers have an output voltage range of
–75V to +75V. The 24V DC power supply
requirement offers the possibility for
battery powered operation. With an output
noise below 3mVrms, this amplifier will
enable many measurements in different
applications.
Safety
- This product is able to produce over 75V,
but the 50kΩ output impedance limits the
current to a rather safe maximum of
2.5mA. This voltage can be painful, but will
not be lethal (under normal circum-
stances). Nevertheless take care. This is a
high voltage unit and safety measures
should be taken accordingly.
- The internal circuitry of the amplifier
operates at high voltage. Only qualified
personnel from Falco Systems should
service it.
- When the amplifier is turned on or off, a
short voltage spike may appear at the
output which may damage circuitry already
connected to it.
- Replace the fuse with 250V 315mAT
5x20mm rated fuses only.
- This product is only suitable for indoor
use in a class II environment (domestic,
light industrial).
- The power supply connected to the
WMA-005/005LF should be double
insulated (class II) or a SELV type (SELV
= Safety Extra Low Voltage, typically a
battery).
- The WMA-005/005LF is a class III
product. Do not connect the amplifier to
the mains safety earth. If this is done, the
system becomes a class I apparatus with
class III isolation, which means that the
protective insulation may be inadequate.
Doing so (only under laboratory
conditions) is fully at the users’ risk. Risk
of electric shock!
- The WMA-005/005LF should not be used
above 2000m altitude to prevent electrical
breakdown.
- This product should only be cleaned with
a soft, slightly moist cloth. Unplug the
WMA-005/005LF from the DC power
before cleaning.
Input protection
A low-noise amplifier like the WMA-005 or
WMA-005LF can never be made fully
insensitive to input overload conditions, as
this would limit the performance of the
amplifier to an unacceptably low level. The
absolute maximum input voltage is ±15V.
Warning: exceeding this spec may cause
permanent malfunction of the amplifier and
is not covered by the warranty!
For normal operation, input voltages
should remain in the -3.75V to +3.75V
range, resulting with an amplification of
20x in an output voltage swing of more
than -75V to +75V.
Ouput protection
The WMA-005/005LF has been designed
to be fully stable with all capacitive loads.
It has been optimized for its step-
response, but is also a very good linear
and sine-wave amplifier. No significant
overshoot occurs at any capacitive load.
Overloading or short-circuiting this
amplifier will not break down the amplifier,
due to the 50kΩ current limiting resistor
that has been employed at the output.
Although the amplifier cannot be damaged
by a short-circuit condition or capacitive
loading, two situations should be avoided:
- Connecting a charged capacitor.
- Using high inductance values (coils).

!
3!
Figure 1. The 10x probe connected for monitoring the output signal
The load
The output impedance of the WMA-
005/005LF is 50kΩ. The amplifier is
generally used for high-impedance
applications where the load is mainly
capacitive. This is the case for MEMS
devices, EO-modulators and piezo
actuators alike. It should be noted that a
coaxial cable also presents a capacitive
load of approximately 100pF/m. The
cables and capacitance that are
connected often limit the maximum usable
frequency due to the first order RC filter
formed by the output resistance of the
amplifier and the connected capacitance.
If output monitoring is required, it is
recommended to connect a 10x
oscilloscope probe to the output. A special
BNC to probe tip connector is usually
supplied with the probe (Fig. 1). However,
you can choose a different way of
connecting the oscilloscope, as long as
you mind the high output voltage. Pieces
of non-coaxial cable in the connection can
cause overshoot in the oscilloscope
reading.
The amplifier is capable of amplifying
above 9kHz, and should not be used for
telecommunication as described in the
R&TTE directive 95/5/EC. To prevent
unwanted radiation all cables should be
kept shorter than 30m.
Noise and offset
The WMA-005 is a low noise amplifier.
The output noise is typically below 3mV
rms. If this is not low enough, the
dedicated version WMA-005LF is
available. It provides less than 0.1mVrms
noise: however, the bandwidth is limited to
DC – 50Hz (-3dB) instead of DC – 20kHz
(-3dB).
Power supply
Use a 24V DC power supply with a
continuous output current capability larger
than 200mA. If the power supply has an
adjustable current limit, it should be set at
200mA or higher too. Falco Systems offers
a suitable 24V power supply, for more
details please visit
www.falco-systems.com/products.html
Amplifier characteristics
In the following pages several amplifier
characteristics are shown:
- Frequency response (Fig. 2, 3)
- Square wave response (Fig. 4, 5, 6)
- Influence of a capacitive load on a
square wave output (Fig. 7)
- Triangle & sine response (Fig. 8, 9)
- Noise & offset (Fig. 10, 11)

!
4!
Figure 2. Frequency response at 250Vpp output voltage
Figure 3. Frequency response at 200mVpp output voltage
140
120
100
80
60
40
20
0
100101102103104105
WMA-005
WMA-005LF
Amplitude ( Vpp)
Frequency (Hz)
200
150
100
50
0
100101102103104105
WMA-005
WMA-005LF
Amplitude (mVpp)
Frequency (Hz)

!
5!
Figure 4. 150Vpp 1kHz square wave
Figure 5. Full scale 10kHz square wave
Figure 6. 30mVpp 1kHz small square wave output signal

!
6!
0pF
470pF
2.2n
100pF
1nF
10nF
Figure 7. Full-power 1kHz square wave response with different capacitive loading conditions.
The 50kΩ output resistor limits the speed at which the capacitor can be charged.

!
7!
Figure 8. Triangle wave 150Vpp 1kHz
Figure 9. Sine wave 150Vpp 1kHz
Figure 10. Noise (less than 10mVpp or, equivalently, less than 3mVrms) and typical DC offset
(-1.1mV) for the WMA-005. The high voltage generator frequency (around 150kHz)
contributes considerable to the overall noise. This measurement was performed with 1m of
coaxial cable connected to the output.

!
8!
Figure 11. Noise (about 0.2mVpp or, equivalently, less than 0.1mVrms) and typical offset
(+1.5mV) for the WMA-005LF
Technical specifications
Amplification: 20x, fixed
Bandwidth: DC – 20kHz @ -3dB large signal bandwidth (DC – 50Hz for the WMA-005LF)
Power supply: 24V DC, 180mA, can be battery powered
Output voltage: -75V to +75V
Noise: <3mVrms noise over the full bandwidth typical for the WMA-005; -1.1mV offset typical
Noise: <0.1mVrms noise over the full bandwidth typical for the WMA-005LF, +1.5mV offset
typical
Input impedance: 100kΩ
Output impedance: 50kΩ
Stability: stable with all capacitive and resistive loads, no overshoot > 5%
Fuse: 1x 315mAT 230V
Operating temperature: 10 – 40°C
Storage temperature: 0 – 60°C
Relative humidity: 10 – 90% non-condensing
Maximum usage height: 2000m
Dimensions: 50 x 100 x 26mm excl. BNC connectors
Weight: 300g
Country of origin: The Netherlands
HS code: 8543 70 90
Specifications may be subject to change.

!
9!
Harmonized standards
This product complies with the following
harmonized European standards:
Safety: EN61010-1
EMC: EN61326
WEEE and RoHS
Do not dispose of the WMA-005/005LF
amplifier as standard waste, but discard it
at a WEEE electronic waste collection
point. The amplifier has been built in
compliance with the RoHS directive.
Warranty
Falco Systems products are guaranteed
against malfunction due to defects in
materials or workmanship for a period of 1
year from the date on the invoice.
If a malfunction occurs during this period,
the product will be repaired or replaced
without charge. The product will be
returned to the customer free of charge.
The warranty does not apply to:
- Exterior finish or appearance.
- Malfunction of the product resulting from
use or operation in other ways than
specified in the user manual.
- Malfunctioning due to misuse or abuse of
the product.
- Malfunctioning occurring after changes or
repairs have been made by anyone other
than Falco Systems.
To obtain warranty service, inform Falco
Systems via info@falco-systems.com
You will receive support and further
instructions.
Falco Systems will not be liable for any
consequential damages, including, without
limitation, devices or equipment connected
to the product, injury to persons or
property or loss of use. For more details
see the Falco Systems Standard Terms
and Conditions of Sale, which can also be
downloaded on www.falco-systems.com
User manual version
User manual version: 2.0
Date: March 26, 2020
Falco Systems
Falco Systems BV
Remisestraat 1
2225 TH Katwijk aan Zee
Phone: +31 (0)6 21840996
Email: info@falco-systems.com
Website: www.falco-systems.com
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