Q
Smart
TECHNOLOGY
Crocodile clip lead (set of two leads) Product No. 3260
DATA HARVEST
Data Harvest Group Ltd 1 Eden Court, Leighton Buzzard, Beds, LU7 4FY Tel: 01525 373666 Fax: 01525 851638 e-mail: sales@data-harvest.co.uk www.data-harvest.co.uk
DS 074
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No 2
Smart
Q
Crocodile clip lead (set of two)
TECHNOLOGY
Introduction
A Crocodile clip lead is a one-metre length lead, which ends in a pair of crocodile clips. When the crocodile clips are not connected the circuit is open (OFF). When they are connected the circuit will be closed (ON). A Crocodile clip lead is normally used attached to a home-made or commercial switch. They can be used singly or in pairs to provide timing and event monitoring.
Connecting
If Smart Q Crocodile clip leads are used for Timing operations (e.g. measuring time and speed) and only one lead is used, it must be connected to the input labelled A. If two leads are used they must be connected to Input A and B. If the Crocodile clip lead is used to record non-Timing data e.g. in EasyLog mode, it can be connected to any available input. Used in this way it can trigger the start of a recording or mark an event such as the addition of a chemical. • •
Use a sensor cable (supplied with the EASYSENSE unit) to the mini DIN socket on the Crocodile clip lead to the input socket on the EASYSENSE (locating arrow facing upwards). The EASYSENSE unit will detect that a switch is connected and will either show as On/Off or as a percentage value, depending on the application used e.g. in Timing it will be On or Off, whereas in Graph or Meters it will be displayed as a percentage signal (under 10% when Off and over 90% when On).
Investigations • • •
Timing an event with the crocodile clips attached to a ‘pupil’ designed switch e.g. a pressure mat sensitive enough to detect a small animal. A Reaction time investigation – using a home-made reaction switch with a simple circuit and lamp. Gravity investigations – record the time from A to B as an object falls using a home-made digital ‘target area’ as input B.
Set up the investigation so the object falls through one Light Gate (connected to input A) and lands on the target area. Make the target area from a piezo transducer fixed to rigid but flexible plastic tray. Connect the leads from the transducer to the crocodile clips (switch Off). Connect the crocodile lead to input B. When the object hits the plastic sheet the transducer will be distorted, which produces a small voltage and makes the switch On.
Simple push switch
Lamp
3260 Crocodile clips
(No more than 3 volts)
Smart
Q
Crocodile clip lead (set of two)
TECHNOLOGY
Light gate connected to input A
Plastic component tray
Crocodile clip lead connected to input B
Piezo transducer
Timing an event 1. 2.
Two Crocodile clip leads can be used (with home-made or commercial switches) to record the time and speed that an object/event takes to travel from the switch connected to input A to the switch connected to input B - Time and Speed from A to B. Timing will start when the signal at input A changes and stops when the signal at input B changes. One Crocodile clip lead can be connected to input A and used to record the time a circuit was closed (the switch was ON) - Time at A.
The calculation for speed at A makes use of the length of a single interrupt card/object that passes through a switch. The calculation for speed from A to B makes use of the distance (in cm) measurement between the connected switches. If a measurement is not valid or possible then the values for speed will not be correct and should be discounted.
Marking an event
A Crocodile clip lead can be used (connected to any of the inputs on EASYSENSE) to mark a point or the length of an event whilst data is being logged. If the clips are connected during logging they will alter in value from under 10% when Off to over 90% when On, to create a spike to mark the event. If the switch is left On it will continue to mark until it is switched Off. Magnesium ribbon
Example: In a calorimetry investigation pieces of Magnesium ribbon are dropped into a beaker of Hydrochloric acid. The Magnesium ribbon was held in a peg, which was wrapped in foil and attached to the crocodile clip lead.
Crocodile clips
Metal foil
Metal foil
Peg Crocodile clips
Smart
Q
Crocodile clip lead (set of two)
TECHNOLOGY
When the peg was opened the switch went from 100% down to 0% and back again so the release point is clearly marked on the Graph.
Using a switch as a trigger
Digital switch-type sensors can be used to trigger the start of a recording. Once set data will only s�������� tart to ��� be ������������������ captured when the ����������������������� condition�������������� specified is ���� met. Example: Trigger on Level is available when both real time and remote logging,. Recording will not start until the switch is above, below, rises above or falls below a set value. A digital sensor will show a value of less than 10% when Off or above 90% when On. In remote logging, Trigger on Digital Condition is also available. Recording will not start until the digital sensor connected to A or B is On, Off or is rising to On or falling to Off.. If rising to On is selected logging will start as soon as the switch is closed (On). If falling to Off, logging will start when the sensor goes back to Off after it has been switched On.
Warranty
All Data Harvest Sensors are warranted to be free from defects in materials and workmanship for a period of 12 months from the date of purchase provided they have been used in accordance with any instructions, under normal laboratory conditions. This warranty does not apply if the Sensor has been damaged by accident or misuse. In the event of a fault developing within the 12-month period, the Sensor must be returned to Data Harvest for repair or replacement at no expense to the user other than postal. Note: Data Harvest products are designed for educational use and are not intended for use in industrial, medical or commercial applications.
WEEE (Waste Electrical and Electronic Equipment) Legislation
Data Harvest Group Ltd are fully compliant with WEEE legislation and are pleased to provide a disposal service for any of our products when their life expires. Simply return them to us clearly identified as ‘life expired’ and we will dispose of them for you.