Data logging related contributions from mail and message boards 

Burning a Candle

Hello! Forgive me for intruding like this, but I stumbled over the Burning a Candle experiment. The page led me to hope that you might know the answer to a question I am faced with: a burning candle gives off more heat than light, but how big is the heat part (proportional to the light-energy) of the energy produced? Dorf, MSc Computer Science

Scooter logging

I work for a scooter magazine, and we are looking for a simple data logging device that we can use to accurately measure and record top speed and acceleration of various test scooters. Can you come up with any suggestions or point me in the right direction? Cheers, Sticky. email: sticky-uk@bigfoot.com

Auto-Graph Plotter

I have attached one of our recent developments - an auto-graph plotter for Excel. Feel free to use it as you like. I wondered if it could be of use in the course that you run. Jim Davis jimdavis@tinyworld.co.uk

History of data logging

In connection with an M.Ed project I am looking for information on the history of datalogging i.e.datalogging with BBC computer and/or with Apple II computer. Can you suggest a source of such information? Thanks Roberts_sean@iolfree.ie Carrigaline

Measure location of water flow

Scott says: I'm doing an business plan for an entrepreneurship class project, and I'm trying to find out some data. I want to build a device that will measure location of water flow, basically, I have a 6" by 6" pad, and I want to be able to tell a CPU where on that pad say, water on from a tight water stream is hitting it, I am also looking for the costs associated with such a pad.

Self heating coffee

Peter Milford writes: a visit to Sainsbury's provided something new from Nescafe – a self heating can of coffee complete with milk and sugar. Umm - some basic science here I thought. The can contains 200g of coffee in a ring pull container - with a push button to activate heating on the base. When activated, the can heats the contents to about 50 Celsius in 3 minutes. Perhaps a good data logging experiment here - put a sensor on to the outside or into the can after activation. Check the rise in temperature with time - then calculate the power input (about 140 W) and compare with a microwave, portable heating element, bunsen etc. The label says that the can contains CaO and NaOH - plus water. Pressing the button breaks a seal and allows water to flood the lime generating an exothermic reaction. Quite a nice example. Oh - and the can costs about a pound a time. Personally I prefer tea, perhaps that is next!

LogIT Lab 2

LogIT Lab 2 has several 'Icon' levels for young students (large fonts, fewer menus) and also a Manager option for things like the security stamp and file management - the manager should not normally be used by students on students computers.

Anyone who has LL1 can upgrade free by downloading the demo version from our web site which automatically detects whether you have a full version of LL1 and upgrades to full LL2. There is also now a 32 bit version on the site too.

IT in Science lab setups

Stu writes: We are planning to build an IT lab in the near future and wonder if anyone has experience of such a design. It would be a lab for the 3 sciences to share with space for some 15 machines.

A good number of schools have IT in Science labs. A school in Milton Keynes has octagonal benches with system units underneath which struck the right chord. I don't much like secretarial college style IT rooms though to some they look smart. ‘Time’ sell an i-Desk which I think is more the way to go if not this exact thing. Schools that don't have dedicated rooms but still can fly anyway use wireless networked laptops.

Upgrade loggers

I am a technician at a South London 11-16 secondary school and have been asked to research a possible upgrade to our present LogIT system. This was purchased a number of years ago and we use the Link software package. How would you advise upgrading our current equipment, which is in good working order? Or, should we be looking at alternative data logging equipment? Any suggestions would be appreciated.

Uses for Low Air Pressure sensor

·                    Transpiration of a plant - measure pressure (through stem); temperature, humidity over time and see if you find a pattern

·                    Meal worms respiration - measure use of gas in a tube with a CO2 absorber

·                    Osmosis - show differences between two solutions eg high/low conc.

·                    Action of an enzyme - gas is evolved from catalase acting on peroxide and this could be the basis of an A level experiment.

Motion sensor problem solved

My Science Workshop Motion Sensor works much better on short range setting. When I use the long range setting if I point at a target 1-2m away the trace is punctuated with spikes.

Scott replies: I am sorry to hear that you are having this difficulty. As you probably know, the Motion Sensor sends out a series of ultrasonic pulses and measures how long it takes for the pulses' echo to return to the sensor. When you use the short range setting, some filtering is used to reject weaker return echoes that might be detected on the long range setting. These false echoes can come from objects that are slightly off-axis. Thus, if you find that the short range setting gives you better results, you should look for any objects near your target, at the distance that the spikes occur that might be causing the false return echoes and remove them from around the target.

Another suggestion would be to tilt the transducer assembly slightly, so that the degree indicator reads about five degrees. This ensures that you do not receive false echoes from the lip of the Motion Sensor. You can use a flat reflective surface to improve the signal from your intended target. Finally, if you have objects that give you false return echoes, you may wish to try and cover the objects with cloth or foam to lessen the echo signal from these objects. I hope this information will help your situation. Please contact me if I can be of further assistance. Best Regards, Scott

pH electrodes 

Dave says: pH electrodes are extremely high impedance devices (>10 to 12 ohms!) and very subject to interference from computers around them. All pH electrodes are fitted with screened cable but the platinum part at the end can still act a bit like an aerial in an electrically noisy environment. Notebooks and their power supplies are especially noisy (often 'switch-mode' types - try them near a radio!) One fix could be to run the notebook off battery power but they should all conform to European EMC emissions standard.

Best logger 

I wanted to ask you a question about Data Harvest compared with Philip Harris . DH are making strong inroads against PH, DH seem to have very user friendly software and attractive pricing. Also, their range of hardware is more compact and doesn't have such a "clunky" feel. I am paraphrasing comments I have picked up, but I am sure you will understand what I mean. Are you able to make any comments about how you see the relative strengths and weaknesses?

Cheers. Answering these questions has always got me into trouble. There are lots of kits in all prices over here. Just from going from school to school I'd reckon that Data Harvest and dcpmicro.com hold most of the market. Datadisc from PH is streets behind Insight in curriculum relevance. My PH stuff is in the garage. Regards , Roger

Strategies

Denise writes: I am a Chemistry teacher in Brazil . We have 3 labs, all of them with one computer with a big TV screen connected, one Datameter and various sensors: temperature, pH, conductivity, oxygen and light. We also have some of your books, which I have been using a lot lately. Normally we use this equipment as a demonstration for the whole class. Now, we are planning to get more computers, Datameters and sensors to be able to have all students working with them. Of course we are all concerned about the strategies would be better to introduce this kind of work with our students. Best regards, Denise

Gas temperature / pressure experiment

Alan says: A school has just submitted a cool science experiment modelling the gas temperature / pressure relationship using a squash ball. What I like about the experiment is the novel use of measuring fast changes in sound level. I notice you feature a few experiments on your web site. If you would like to put a copy of this one on your web site, please feel free to do so. The URL is http://www.picotech.com/experiments/squash_ball/index.html

The Video data logger - calculating g

A resource for AS level which allows you to calculate the acceleration due to free fall by taking measurements from a digitised video sequence. It could be given as an assignment for students to complete. http://uk.geocities.com/petergolton/

Educational data logging

We are getting into educational data logging and experiment control. Have a look at my website - http://www.vinstrumentation.com. The general virtual instrumentation, logger and control software demonstrations can all be downloaded. Regards Alex , Glasgow, abg@vinstrumentation.com

 Data logging with Windows Terminal Services

Garry writes: The school is looking to use Windows 2000 terminal services to reduce our computer equipment costs. Do you know if Insight2 and other science software will not work in this configuration?

If TS runs on the server I wonder how will it access the Com port on the local machine? Mind you, Insight is so light on computer resources it’ll work on the oldest machines still working.

Subject: Data Harvest equipment

John writes: The following points are offered in the light of experience with Data  Harvest gear this year. We purchased a class set of EasySense loggers and sensors this year. They have worked well in class except for the following faults which could prove costly in the long run for anyone wishing to use this sort of kit with whole classes of students. The connectors for the sensors have multi-pin plugs which it is easy to bend if you try to insert them incorrectly. It does not take much force to do this. When you try to straighten the pins they tend to snap off. This renders a sensor useless as repairing the leads is nigh on impossible – they are wired in a complex fashion. This means that a moment's lack of concentration by a pupil can mean a bill for a new sensor - e.g. £29 for a light gate. A related fault is that if a damaged plug is inserted into a data logger it can and has blown a fuse internally on the logger and means it does not work, Data Harvest have soldered surface mounting miniature fuses to the pcb. These they claim need to be replaced at the factory. Why they could not have fitted reset-able fuses or ones which a technician could replace is beyond me. We have spoken top their technical department who say that new models are being fitted with re-settable fuses - too late for us it seems. Previously Data Harvest gear has been fine - the EasyLog model with larger DIN style connectors for sensors and D type serial port connectors have proved very robust in use over a number of years. I feel that the drive to cut costs may have been taken too far in the case of EasySense. I would be interested to hear of others experiences with this kit.

RF replies: It's pretty clear from this that Data Harvest could have done better with that connector. In the real world people make mistakes and take a while to admit it find a way forward. It's to their credit they've revised the design, turned this round and ended up with something that's better than many.

Steve Whitely of Data Harvest (www.data-harvest.co.uk) replies

Firstly John is obviously not happy with us, and I would like the opportunity  to try and correct this.  Secondly, in our defence: We chose the mini-din connectors as these are widely used by Apple (keyboard and mice) & IBM (mice) & Fourier (sensors) and so we assumed they would be robust enough. In hind sight we agree that they have caused some problems. Anyone purchasing sensors from us now will find that the plastic casing has been altered so that it is impossible to insert the connector upside-down curing the problem of bent pins. Our research showed that it was when connecting to the sensor they tended to 'spin' the plug as they were usually reading the bottom of the sensor at the time (to see the label telling them what the sensor was)   It is unfair to say that 'lots of sensors are ruined' - we purposely designed the EasySense system to use cables that can be removed from the sensor and replaced if damage occurred (something we were asked for from our Sense & Control users) there are now only 2 major sensors that still have the cables permanently attached to the sensor (Light gates and Pendulum) - both of which are currently being re-engineered so that the cable will be replaceable. In addition, the removable sensor cables we use are standard 'off the shelf' cables which may be purchased from us or any cable supplier.   For a very long time now, we have supplied all EasySense with 're-settable' fuses and any units that are returned to us with old-type blown fuses are automatically upgraded to use re-settable fuses - so it is not 'too late' for existing customers - we try hard to never leave any of our customers behind!