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About the Course
Bluetooth Speakers is a two-day course where the students design (within reason!) and build their own high-quality Bluetooth speaker. We use an off-the-shelf Bluetooth amplifier module, together with some good quality speakers and a simple laser-cut enclosure to build a quite respectable sound system.
The aim is to get the students:
- Learning about 2D design for the laser cutter
- Learning some soldering techniques
- Learning a bit about the acoustics of speakers
This is an unusual course is that it is run as a 'split' course in the summer - this means that they come on the first day an then there are several days before they next come in for their second session. This is to allow us time to laser-cut their enclosures and ship them to the venues.
This will also be the case at Winchester as we will be doing the laser cutting off site, so we will run the days in this order when doing all of the courses that make up the Gadget Combo:
- Bluetooth Speakers day one
- Physics Game Design
- Robot Brain Surgery
- Gadget Factory
- Bluetooth Speakers day two
Health and Safety
This course involves soldering, so the following precautions need to be taken
- Soldering irons will be kept off/unplugged unless being used
- Students are warned about the dangers of soldering etc (see below in the comments about running the session)
- You should be aware (as should the students) where the closest cold water tap is in case of burns
- Students wash hands when they go on breaks if they have been soldering
- Staff are always vigilant for inappropriate use of the soldering irons
In addition, please read the soldering risk assessment.
The Kit List
Student consumables (per student to take home at the end)
- 1 x Bluetooth amplifier module
- 2 x 4-ohm speakers
- 1 x 5V power supply (with 2.1mm plug which is cut off)
- 3 x Pushbutton switches
- 4 x 40mm M3 spacers
- 15 x 10mm M3 posidrive machine screws
- 7 x M3 nuts
- 2 x A4-sized sheets of 3mm Acrylic (will be cut out and provided by Tech Camp after their designs have been created)
- 2 x 150mm Black/red twin jumper wires
- 4 x 100mm single jumper wires (black/green/white/yellow)
- 2 x 5mm acrylic laser-cut feet (pre-cut by Tech Camp)
Student tools (one per student, not to take home)
- Disposable plastic bowl (for temporarily holding the small parts when handed out)
- Computer for 2D design work
Student tools (one per pair, not to take home)
- Soldering iron with stand
- Small amount of solder (around 30cm wound in a loose loop)
- Small phillips screwdriver
General class kit
- One 5m extension lead per 8 students (for soldering irons/laptops)
- 1 x 4-way power board per 4 students (for soldering irons/laptops)
- 1 x Ream of paper
- 1 x Box of pencils
- Several x Erasers
- 1 x Demo Bluetooth speaker
Pre-Camp Setup (By Tech Camp)
- Laser cut a few spare 'stock' bluetooth enclosures in case anything goes wrong with one of the students' designs
- Laser cut the 5mm perspex feet - two for each student, plus a few spares
IT Systems Check
- Inkscape installed and fires up
- Sound and USB ports functions on computers
- Student logins work for this website
- All videos work in the student guide
- Check following websites are available:
- vimeo.com
- images.google.com
- courses.techcamp.org.uk
Preparing Yourself
Like any practical course you'll find this much easier to teach if you have run through it yourself as completely as possible first. Even if you're experienced with electronics this will allow you to find out which parts of the course are tricky. Also, when we're running a course for the first few times there may be the occasional mistake or parts of instructions that are not clear and this is a great way of identifying them.
As a minimum, you'll need to:
- Read through this guide completely and be comfortable with it
- Work through the Inkscape tutorials yourself to make your own design
As a tutor you will not actually physically build a bluetooth speaker of your own for a couple of reasons:
- As an adult, the build process should be quite simple
- You would be better concentrating your time on the Inkscape work
- There may be minimal spare components at the event.
As the start of this course is tutor-led you'll also need to run through your delivery of the course a couple of times - ideally out loud, but at least in your head. If you are working with more than one tutor, you will want to decide between yourselves how to split the tasks/explanations in this initial part of the lesson.
Pre-course Setup
This workshop needs both soldering and work at a computer. As the instructions that the students need to follow are online, ideally the soldering equipment would be nearby the computers. However if space does not permit, and there are plenty of spare desks elsewhere in the room you could set up separate soldering and computing areas but be aware that there could be a lot of movement between the stations so this is not ideal.
If working in a classroom without computers (when using Tech Camp laptops) it is important that there are no trip hazards caused by laptop, soldering iron and extension lead cables. Generally if you have choice of classroom layout you will want to have the tables around the perimeter of the classroom, or at least small rows of tables coming out directly from sides of the classrooms (no side aisles) so that any cables can come from the wall to the tables without crossing a walkway.
As the students will be doing the 2D design work first, there should not be much setup on the first day. On the second day though, you will need to setup the desks with all of the small components before they arrive.
Rules for Students
- Students must use soldering equipment properly (see below)
- If they lose components they must find them! It's very easy for small components to be dropped, so looking around the workspace (and on the floor) should be the first thing done when they claim not to have something. We have limited numbers of spares.
- They must check their 2D design work rigorously before showing you (who will check as well) - unless their 2D designs follow the guidelines, they will either not be cuttable, or not be able to be assembled which will be a real disappointment to them. They should not use any Inkscape tools that are not in the tutorials.
Guidelines for Tutors
Running a practical course like this is always tricky, but this course has some moments that you'll want to watch out for ...
- Getting a cuttable design from the students is a challenge - they might want to add other things using tools in inkscape that we have not shown them how to use. This can quickly cause a design to be uncuttable, so discourage them from doing this. Their design should purely use the line-based drawing tools in the videos and not have engraved text, etc.
- It is very easy for the students to not follow the video guides exactly, and end up with cuttable (but unworkable) designs. As a tutor, it is your responsibility to hand-check each design before sending it to be cut. Will the design overall work? Are the holes in the right positions? Are the spacings between elements correct? You'll need to check out the important subsections in particular (like the one large and four small holes that make up the speaker cutout and the four small holes and two rectangular cutouts that make the bluetooth module mount) but we're really relying on you to predict other potential problems. Look at their designs and imagine them assembling all the components. Can you see any problems? If so, you need to correct them before sending the design on (or ideally get the students to correct them during class time).
- For some students this might be their first experience of soldering so they need some direct instructions and some close supervision when they first try this out (see below).
- Don't give 'spare' components out to students - the supplied kit list should be stuck to.
- Don't ever give to the students the large reel of solder - always keep this in a tutor-only area and hand out small amounts as they need it. (It's not unusual for students to see what happens when they push the soldering iron directly onto the solder reel ... what happens is that the solder strands all quickly melt together and the once useful and expensive reel has to be binned, leaving you with a course to run and no solder to use!)
- As always, if anything gets broken, flag it up to the Technical Manager as soon as possible so that spares can be checked if needed.
Running Session 1
Preparation: You'll want to heat up a soldering iron in your 'demo area' and have access to a screwdriver to partly disassemble the speaker.
- Tutors introduce themselves
- In Bluetooth Speakers, you will be learning :
- How to design a simple laser-cut enclosure for their speaker
- How to make a speaker sound really good
- How to do some simple soldering
- Demonstrate the sample speaker - play some music!
- Show them how the basics of the design - two laser-cut boards with spacers and feet
- Explain that this not only holds all the components together (and makes it look better) but also helps the sound alot.
- Now get the students standing around a table while you demonstrate the following :
- How a speaker works (magnet/coil, pushing air in and out quickly, etc)
- How that when the front of the speaker cone pushes outward, the back is moving in. If there is no enclosure, lots of the air from the front just spills around the edge and gets sucked in the back rather than being sent out towards the listener. The effect is really bad on the sound quality, particularly on the low frequencies.
- Demonstrate this (Unsolder one wire of one of the speakers. Remove the back panel and four screws from the OTHER SPEAKER and take this speaker out. Play some music now and you'll hear this poor quality from the single still connected speaker (that is now not mounted in the panel).
- Whilst playing the music, push the speaker towards the panel cutout. This will show them why you need a cover to make it sound better.
- Explain that the ideal cover would be an infinite-sized flat plate with a hole in. This is hard to make but we can make a smaller-sized one (or a closed enclosure like most commercial speakers)
- Tell them that they have to make a few design choices:
- The colour of their speaker (black, white, orange, clear - although they must select both a first and second choice in case we run out of some colours. When they save their file they are instructed to put the colour choices in the filename). Note that the backs of all speakers will be transparent
- The overall shape of their speaker (they are limited to 290mm x 200mm max but it doesn't need to be this big and can be vertical or horizontal).
- The position of the buttons (or they can leave them out and just use the ones hidden on the back if they want)
- Whether they want any other features like a cut-out for a handle
Show them a Google image search for 'Bluetooth speaker' as inspiration and hand out sheets of blank paper and pencils and have them sketch their ideas and dimensions (perhaps 15 minutes) - encourage them to do searches themselves to look at shape ideas first. You will want to roam around helping them refine their ideas and identifying concepts that wouldn't work and explaining why
Show them a basic demo of how dozuki works, including the colours of instruction bullets vs the colours of the annotations on the relevant photo.
The students will then start their online tutorials. The first tutorial is an exercise in them following instructions. This is important! They're drawing a simple face, but the dimensions should be exactly correct. Once you know they can do this successfully they should be able to do their real speaker properly as well. Make sure they are following the instructions and pausing regularly to complete the step. This needs active supervision to work, as some students will otherwise not pay attention to the proper dimensions.
Once they start designing their real speaker you'll also need to keep a close eye on them and continually roam around checking that their designs look good and helping them if needed. When their designs are completely finished, you should do a complete check yourself before emailing the files to j.swanborough@techcamp.org.uk. For the front panel, you will need to check:
- Are there designs within a 290mm x 200mm rectangle?
- Are the mounting holes the right size (this includes the screw holes, mounting holes for buttons and speakers)?
- Are the pair of five holes for mounting the speakers all the right size and spacing?
- Are the minimum spacings between speakers and switches maintained?
- Do they have anything silly on their design that needs removing (like text, pictures, etc)?
For the back panel, you will need to check:
- Are the four mounting holes for the spacers in exactly the right positions (compared with their front panel)?
- Are all of the mounting holes for the Bluetooth module properly sized and positioned?
- Is the overall size suitable (should just be a little bigger than the rectangle formed by the four mounting holes for the spacers to give them a decent margin)?
- Is the position where the USB power cable will come out suitable? (This should be fine if they follow all the guidelines unless their speakers (and therefore the spacers and the back panel) are very low on their front panel and/or they have put the Bluetooth module very low on the back panel as this could mean there isn't enough room for the cable to come out before it hits the desk).
Once their designs are finished (and double-checked by you) please email the files to j.swanborough@techcamp.org.uk and they will be cut out and sent to the venue. Please try to do this asap - ideally at the end of this first day to give us plenty of time to cut them out and get them to you.
Running Session 2
- Ask them how many have soldered before?
- Ask those who have to give some safety tips to the rest of the class. You will want them to suggest (or you) at least the following:
- Where the hot parts are - you need to be very explicit here, showing them the difference between the metal parts and the plastic parts and tell them if they touch the metal parts it will hurt!
- The irons must always be kept in the stands when not being used
- The irons must only be used to solder parts as per the instructions
- The irons must not be used to make 'solder blob monsters', melt plastic or other materials (it releases toxic gas as well as damaging things) or as a weapon!
- The irons must only be turned off after use
- If they do burn themselves they need to go to the closest water tap and run their hand under running water (show them where this is - the tap that is, not their hands ...)
- They need to wash their hands at the end of the session.
- Tell them that if they haven't soldered before, you'll be there to help and that they should let you know when they're ready to solder for the first time so you can help.
- Show them the sample speaker and explain how it goes together (this is repeated in detail in their guide but it really helps for them to understand before they start):
- First, put the speaker in the back and push four screws in the front
- Secure the screws by attaching four spacers on the back
- Repeat with the other speaker
- Push in the buttons and secure on the back with spring nuts and nuts
- Attach the bluetooth module to the back board using nuts and bolts
- Solder the wires onto the switches and speakers
- Thread them through the holes on the back cover and solder onto the board
- Screw the back board on
The students can now work through their guide to assemble their speaker. When finished they can pick up a power supply and test out if they have a phone (probably in an adjacent room or corridor outside so the noise isn't too disturbing! Please note that the modules will all have identical wireless names so it is only feasible to test one at a time - if multiple speakers are turned on at once, the active one will be randomly selected from all of them, making it hard to test any of them!
Bluetooth Speakers Student Guide 2
Extension Challenges
The building of the bluetooth speaker will not take the entire second day. For this reason, we have included in your supplies components for an 'extreme soldering' session.
There are two parts to this.
The first part involves soldering 40 resistors to a board (4 sizes, increasingly getting smaller). This is good preparation for the second part but this board doesn't really do anything. If you need to cut this session short you can - it's more important they get the second part done.
The second part involves making a wrist-mounted light. They can take home both projects.
Both projects are documented in their student guides.
Please be aware that the surface mount parts are very small and easily lost, so you'll need to keep a keen eye on the students - making sure that they don't lose any bits. It is up to you how to organise these sessions.
Packing Up
Your supplies should always be packed up as neatly as they came! This means:
- Components are in labelled bags, and grouped in bigger bags
- There should be no bags of unsorted components