USB DrDAQ User's Guide
17
Copyright © 2013 Pico Technology Ltd. All rights reserved.
usbdrdaq.en r4
11.
Leaving enough free wire to make the connection, secure the leads by looping
them around the central boss of the case. Alternatively, put a cable tie around
the leads inside the case and near the hole. Make sure that the leads are
securely held inside the unit.
12.
Push the bare ends of the leads into the holes in the back of the terminal block.
There should be one lead in each hole.
13.
Tighten the screws in the terminal block and check that the leads are held firmly
in place. Do not overtighten the screws.
14.
Put the lid back on to the unit. Make sure it is on the right way round.
15.
Tighten the fixing screw. Be careful not to overtighten it.
16.
Check the operation of the external switch. Connect up the unit and make sure
that PicoScope or PicoLog shows near to 100% when your external switch is
open and 0% when it is closed.
2.9.5
DD101 Humidity Sensor
DD101 Humidity Sensor measures humidity using a 'non-condensing' technique. It
has a short response time and plugs into the external sensor connections of USB
DrDAQ.
Size
72 x 45 x 28 mm
Operating range
20% - 90% Relative Humidity
Overall accuracy
Reading ± 10%
Operating temperature
0 - 60 °C
Resolution
0.2% Relative Humidity
Minimum response time
60 seconds with vigorous air movement
Maximum response time
60 minutes in still air
Caution:
Do not allow the DD101 sensor to become wet. The DD101 is a non-
condensing sensor and liquid (including condensation) inside the case may damage it.
The DD101 may be connected to either Ext 1, Ext 2 or Ext 3 on USB DrDAQ.
Tips for use of DD101 Humidity Sensors
The sensor responds to humidity changes more slowly in still air. If you need to
increase the response time, then increase the air flow around the sensor. For example,
swing the sensor gently on its lead or create a constant draft using a fan. Do not blow
into the sensor, as your breath is very humid and will produce incorrect results. Never
allow the sensor to get wet; for example, do not take a cold sensor into a warm humid
environment where condensation may form inside the sensor's case.
Making accurate measurements
The DD101 will give good readings of humidity and show trends well. However, if you
need to make more accurate measurements, you will have to calibrate the sensor. The
calibrated sensor could have an accuracy as good as ± 5% though this depends on
how well the calibration procedure is carried out.
The output of the sensor may vary over time. For this reason you should calibrate the
sensor regularly (at least once a year).
