Table of Contents

Digital Counter Bell Development

Version 1

The first version is a proof of concept. The idea was to in the fastest and cheapest way play a digital sound using the counter bell, leaving the bell intact in case the project would fail.

Parts used:

Finished Product

Images (Click to enlarge)

Video with Audio

Challenges

Conclussion

In terms of requirements, version 1 succeeded in requirements 1(preserve original presentation) and 2 (powering) but failed 3 (Loudness). In addition, the main feature of playing custom audio files does not exist. This version was put together in a fast manner and fails to uphold a standard of quality. Note that the battery is not easily accessible but can be easily created by cutting a hole (as done for the speaker) in the cardboard. This allows access to the battery holder and battery.

This was the first version and a success and proof that this could work.

Version 2

This is the first iteration that will allow custom audio. We will be using the same counter bell but everything else will be swapped out. The following parts are needed (could potentially change over the duration of the version)

I've ordered the following items in the image below. I purchased both a rechargeable poly ion battery as well as a simple 3xAA battery holder (for testing, will most likely not fit in actual product). There is also a USB charging chip for the poly battery and is also for testing purposes and not a necessity at this point. The large speaker will potentially not fit and will require the construction of a laser cut acrylic base. This should not diminish the original

Challenges

Conclusion

This version was a success. There we a couple of things that I wanted to improve, which was the price of the whole project as it was fairly expensive at this point. I haven't previously taken into account the cost of the bell, which in retail costs $12 or more in some cases. A second thing that I found a little annoying is that it got way to crowded and the cabling was difficult to handle when everything was crammed into the housing. A breakdown of this version:

Version 3

There are plenty of changes in this version. After a lot of research and a little luck I have managed to get the price of the components down by more than half. We can easily remove the amp and the expensive soundboard and replace it with a mini mp3 player by DFRobot which takes micro SD cards and can power speakers less than 3W. It's size is about half the size of the soundboard and relinquishes the need for a separate amp. As luck would have it, this circuit can be bought at a fraction of the price from oversees.

I have managed to find a desk bell for $2.80 locally which is a big difference to the retail version I've used in the past.

So hopefully this version will be smaller, use less wires, cost a lot less and be more energy efficient (as a result of less components). Also hoping to find a solution for a button that feels good and also a way to mount the components inside the bell.

Parts

Challenges

The mini MP3 player has only two triggers which means that a single trigger will do several tasks based on how long it has been pressed. This could lead to some problems considering the next button (aka the play button) which we would use as the bell trigger, when held, would continuously reduce the volume.

Phil to break down outcome

Version 4

As the previous build refined the cost and performance in components. This version aims to refine the housing of the components inside. The idea is to add a false base to the counter bell without changing the bell structurally. It is worth noting, at this point, that we are now in the stage of compromise. Version 3 worked for all intents and purposes. To add functionality like Charging the battery while the bell stands upright and remains operational and to ensure that every successful build will be identical, we will need to work the housing of the project. The plan is to add a false bottom to the bell and add extra space for the components to be housed. We also need to substitute the current choice of speaker as it is not possible to source large quantities of that particular size. The final objective its to make the build solderless for participants.

Parts

The parts will be the same as version 3 with the addition of;

Challenges

Adding the new layer of acrylic base will raise the price slightly, I will need to ensure that I don't add any more than required. The new design will see the components glued to the base. This can cause issues with reparations. Retaining as much of the original aesthetic as possible.