PicoLog Self-Help Guide
AR346-1
© Copyright 2014 Pico Technology Ltd.
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Pages 27 to 37 in the USB DrDAQ Data Logger User’s Guide (see Related Documents):
Ext Volts.dds
[Scale1]
Resistor=3.3
LongName=Voltage
Units=Volts
MinValue=0
MaxValue=2.5
OutOfRange=2
Places=3
Method=0
NoOfPoints=2
Raw1=0
Scaled1=0
Raw2=2.5
Scaled2=2.5
If your external voltage has already been attenuated from a higher value (for instance if
you are mea5 V) then you can adjust the scaling to suit such that the correct
voltage is displayed in PicoLog. Simply change two lines in the Ext Volts.dds file:-
[Scale1]
Resistor=3.3
LongName=Voltage
Units=Volts
MinValue=0
MaxValue=5.0
OutOfRange=2
Places=3
Method=0
NoOfPoints=2
Raw1=0
Scaled1=0
Raw2=2.5
Scaled2=5.0
15.7
Device-specific – PicoScope 2203, 2204, 2204A, 2205, 2205A
Clicking relay noise with PicoScope 2203/4/5 including ‘A’ models
The PicoScope 2203/3A/4/4A/5/5A have relays that switch between the high and low
voltage ranges on each channel. When running in PicoLog, the input signal is fed through
from one input connector to both channel’s A to D converters in parallel to get twice the
bandwidth. Then the other input connector is routed through the same pair of A to D
converters and so on in a cycle. At any one time, the unused input connector and
preamplifier chain is set to the highest voltage (lowest gain) condition to avoid injecting
crosstalk onto the live channel. If either channel is set to ±1 V or lower, the gain relay
will cycle continuously.
The way to have two channels in use without the relay noise is to have both set to any
voltage greater than ±1 V (±2 V to ±20 V, and they can be different).
For the smaller voltage ranges less than ±2 V (±1 V to ±50 mV) the clicking can be
reduced or eliminated by increasing the scan time under the Edit Measurements section.
You will need to do this for both channels.
