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Datalogging: The cooling effect of evaporation

This investigation looks at how evaporation can cause cooling. We have used two cups, two dataloggers, some paper towels and some water to measure the effect. We set up one cup with a wet towel on the top, and as a control, we had one with a dry towel.

We don’t need much for this investigation. We used two polystyrene cups, two pieces of paper towel, two  temperature dataloggers and some tepid water.

Within the ‘Mini-datalogger’ software it is possible to configure the datalogger to record temperature samples at varying intervals. We decided to set the dataloggers to record every two seconds, using the ‘single mode’, so we didn’t accidentally lose our data. We also chose to start logging a few minutes into the future, to make sure that we didn’t affect our data too much.

We placed one datalogger into each cup, with the circuitry near the middle. This should allow the air to circulate around the datalogger, giving us the most accurate reading.

Then we wet one of the paper towel squares with tepid water. We had to allow as much water to drip off as we could, so that we didn’t risk getting our dataloggers wet.

We then left them in the cupboard for a few hours, to allow the water to evaporate.

After around three hours, the paper towel was still very wet, so we decided to increase the airflow over the paper towel, by using a fan. This should cause more water to evaporate.

I repeatedly checked on the cups over the final 1hr 30mins as the paper towel on the dry cup kept flying off.

When I returned for the final time, the paper towel on the wet cup had blown off. This definitely proved that the water had evaporated, and the towel was almost dry.

Our initial results looked promising. The cupboard where they were being kept wasn’t heated so the temperature dropped considerably, and after 45mins – 1hr they levelled out. Interestingly, the cup with the wet towel was already lower in temperature than the dry one, and this continued to be the case throughout the investigation.

At around 13:40, the temperature of both cups increased – this was after the fan had been switched on. Due to the nature of the room, and the lights, we believe that the fan had caused the air to circulate, and even out the temperature. We are going to investigate this hypothesis. EDIT: See results.

As we mentioned previously, the wet paper towel had blown off, and it looks like this happened around 5 minutes before the end of the investigation, as there was a sudden rise in temperature recorded on the wet towel datalogger.

So far, it appears that the wet towel does help to cool the contents of the cup down, by evaporation. To see whether we can recreate and improve on our results, we will repeat the investigation.

This time we left the resources for the investigation in the room, for 45 minutes before the dataloggers started recording. This allowed everything to get closer to room temperature. After the first 15 minutes of datalogging, we then placed the wet and dry towels over the dataloggers.

The results this time did match our expectations. There was an initial rise of both temperatures, likely caused by the opening of the door. The wet towel cup continued to rise in temperature, after the dry cup had stopped. This is likely to be caused by the water used being slightly above room temperature – even after sitting out for 45minutes.

The wet towel cup then dropped in temperature, where it stayed about 0.6 degrees celsius below the dry towel cup temperature. The temperatures gradually rose in both cups until around 13:00 – this was when we checked the cups and obviously forgot to close the door! Interestingly, the dry towel cup temperature rose by more than the wet towel cup. The wet towel cup was then consistently around 0.8 degrees celsius below the dry one.

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Christmas has arrived!

Our first proper Christmas since we moved in to our new building with Redfern Electronics (designers of the Crumble Controller). We’ve decided to mark the occasion with a suitably decorated tree!

We connected 20 Sparkles and a Sparkle Baton together using croc-leads. We then wrapped these around the tree, with the Baton on the top. The croc-leads are almost a decoration in themselves!

The Crumble is connected to a Raspberry Pi, which is connected to our network, meaning we can remote-desktop in and change the lights! It’s pretty much an IoT Christmas tree.

We decided to add our big red button near the base of the tree, to allow the user to cycle through the light sequences. The code waits for the button to be pressed (in this case push to break), and then it starts a new sequence of lights until the button is pressed again – then it moves on to the next sequence.

We decided that the tree was a bit bland, especially during the day time, so we added a few more decorations to it.

And there we have it, our IoT Christmas tree, ready to be programmed by anyone in the office.

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Ideas for the Sound Recorder Module

Aim of project: To design and create a voice-recording product

Project Outline:

  • Research existing ‘talking tile’ style products;
  • Design a product which embeds the voice recording module;
  • Make the product;
  • Evaluate the product against design criteria.

Resources Needed:

  • Sound Recording Module;
  • Materials to produce the product.

The main idea behind this product is to design and create a type of ‘talking tile’ in which the user is able to record their voice and if desired, attach an image to the front.

Potential audiences:

  • Young children learning to read/vocabulary improvement;
  • SEND children to assist with communicating (augmentative and alternative communication);
  • Those with memory impairments;
  • Carers for those with Alzheimers/Dementia.

This is an example of the design process in D&T. It can be simplified into design –> make –> evaluate.

To make our product, we need to look into existing products, develop our design specification, plan it, make it and then evaluate it.

design process

Here is an example of how you could embed the sound recording module within a designed product:

1We started off with an initial sketch of our design.

2 We then drew what we imagined the base to look like.

3 After our initial design, we decided to refine it further.

4Then we thought about how our cross section would work.

5After this, we mocked up a 3D design using Tinker Cad.

6We then created a mock-up in cardboard. This definitely allows you to see any mistakes that may be made!

7We made some adjustments to our design, and got it ready for the laser cutter.

8 After the acrylic pieces were cut, we removed all of the protective coating.

9Next, we prepared our circuit to add in a power switch. We also swapped over the record switch.

10Then we connected our components together, and glued all of the pieces.

11And there we have it, our finished recording box. We made a few discoveries along the way, and as such our design changed repeatedly. To add an image or text to this, we could blu-tack it on, or use velcro. It has been a good learning exercise, and upon reflection we would not use hot glue to connect the pieces, as it was messy and we didn’t get the desired finish.

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Halloween: Jitterbug Spider

For this project you will need:

  • A Jitterbug kit;
  • A fresh battery;
  • Paper/Card to make your design or a printed template;
  • Scissors;
  • Paints/colouring pens/pencils
  • Phillips and flat head screwdriver.

Task: To create a Halloween inspired Jitterbug

The Jitterbug kit provides a great opportunity for children to explore simple circuits, motors and the power of forces. The off-center mass, when spun at high speed, creates vibration which causes movement in the bug. The movement can be controlled by adjusting the rubber legs underneath. The bug kit can then be decorated however you wish.

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1First of all, we emptied out our Jitterbug kit to check that we had everything we needed.

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2We then printed out our template, coloured it in and carefully cut it out.

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3To make the legs more ‘leg-like’ we folded them lengthways. We then added a crease about 1/3 of the way along the legs, to add a joint (knee?)

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4After this, we lined up the plastic body with our card version and marked where the holes needed to be. We then pierced these so that the bolts went through. Next,  we glued the legs onto the back of the body, adding sellotape to keep them secure.

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5We then connected the spider’s body to the plastic chassis. We added the nuts onto the bolts and tightened them.

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6Next, we added the plastic tubing for the legs, carefully screwing them on until they were tight.

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7 We then continued the Jitterbug as-per the instructions. We used a piece of spare paper to help keep the motor in place it its mount. We then attached the battery leads to the motor tabs.

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8Finally, we stuck down the battery box, making sure that we could see the switch!

9And there you have it, a Jitterbug spider fit for Halloween!