As well as the built in sensors, DrDAQ has sockets for optional external sensors. When a sensor is plugged in to the external sensor sockets, the software detects it and automatically scales readings. For example if a temperature sensor is plugged in readings are displayed in °C or if a humidity sensor is plugged in, readings are displayed in % RH.
External sensors are optional extras so can be purchased at any time. It is however cheaper to purchase sensors at the same time as a DrDAQ. See the pricing link listed above for more information.
Details of the external sensor sockets are provided with DrDAQ. This allows users (and third party manufacturers) to develop their own sensors.
pH is measured using a standard electrode with a BNC connector. Pico supplies a robust epoxy bodied pH electrode ideal for educational use. It covers the full 0 to 14pH range. The electrode comes complete with a small bottle of storage solution to help prevent it drying out.
Oxygen in air is measured using a galvanic cell sensor which connects to the external sensor sockets using the supplied three metre lead. Simply plug in the sensor and you are ready to measure.
Unlike previously available oxygen sensors, the DD103 Oxygen sensor can measure the full 0 to 100% range. This makes it ideal for many chemistry, biology and physics experiments.
Galvanic Cell (lead-oxygen with weak acid electrolyte)
Input range
0 to 100% oxygen
Accuracy
±3% (Uncalibrated) ±1% (Calibrated at constant temperature / pressure)
DrDAQ Humidity sensor
This sensor is designed for the cost effective measurement of relative humidity. When plugged into one of the external sensor sockets on DrDAQ (using the supplied 3m cable) readings can be displayed in %RH. The sensor has a response time of 60 seconds and can operate over a 0 to 60 °C temperature range.
Our science experiment on transpiration shows the sensor being used to measure the humidity change caused by a plant.
Range
20% to 90% RH (Non condensing)
Accuracy
±10%
Resolution
0.2% RH
Size
72 x 45 x 28mm
DrDAQ Reed Switch
The reed switch sensor can be used to detect the presence of a magnetic field such as from a bar magnet or an electromagnet. Alternatively, a simple external switch can be wired to the internal screw terminals. It has a fast response time of 2ms so can be used as an alternative to a light gate for timing applications. Other used include monitoring the amount of time a door is left open or a machine running.
Our science experiment scalextric subaru challenge shows how the sensor can be used to measure the speed of a model car.
Griffin Rate Meter
The Griffin rate meter provides an indication of the level of radioactivity given off from a source. Our Application note explains how to configure the pH input of DrDAQ for use with the Griffin rate meter.
The rate meter can be obtained direct from Griffin and George, details on their Web site.
DrDAQ Sensor Adaptor
This compact unit will prove invaluable to anyone developing their own sensors for the DrDAQ. A short length of cable is terminated with an FCC 68 4/4 data plug, which is compatible with the external sensor sockets on the DrDAQ.
The four lines are clearly labelled and brought out to four 4mm sockets on the adaptor unit so that external circuitry can be easily connected and developed. Part Number is DD013
