In this instructable I will run through step by step how I created my radio for my Second Year University project. We were given a brief to hack a small portable sony radio and create a re-designed radio to accommodate for a specific chosen user. This radio is designed for my 93 year old grandmother who suffers from blindness and arthritis. The radio consists of a central cylindrical body with the main feature being an extractable key insert containing the battery pack which, when sloted into the top of the main body, turns the radio on and then can be twisted for he volume control.
The general concept of my radio is that the battery pack is taken out of the radio casing into an external, removable key that when inserted into the open top of the new body, connects up the circuit and turns it on. After this, when the key insert is twisted, it controls the volume of the radio. The idea behind this was to make it easier for an old aged user to interact with the radio without small inconvenient and unnecessary buttons.
Here is a link to a short demonstration video of the final prototype.
Step 1: Radio Overview
At the beginning of the project we were each given our own radios to take apart and use for our final design. The handset we were given was a simple fm/am Sony ICF- S22 that you can buy from amazon for under £10, I have posted the link below. This was ideal as it is well built with all the basic functions you need in a standard radio, but easy enough to disassemble and manipulate.
The radio is cuboidal, measuring around 750mm wide x 1200mm high x 250mm deep. To dismantle the radio I first removed all the external screws. Then, with a flat screw driver and knife, gently went around the centre divide slowly prising the casing open, being careful not to damage any of the internal components. The radio circuit board is held down with two small clips that when pulled back loosens the parts allowing the circuit board to be taken out from the case. The small speaker cone was glued to the inside of the front casing, later on to get it out I slightly cut through the glue and pushed though it popping it out with out any damage.
Step 2: Initial Electronics
After carefully taking the circuit board out of the radio casing the first step in terms of electronics is to remove all of the components that will be coming off of the board and extend the wires to each one. In this case the volume control, battery pack and Fm/Am switch all need to be brought out and extended.
Step 3: Building the Outer Housing
The outer casing for the radio is made out of layers of sheet MDF wood. I found this way quite time consuming because of having to make multiple identical rings in order to make the the structure hollow. However later on in the project it was useful to be able to take apart all the different layers of wood to sort out all of the small internal electronics and then glue everything aligned when i knew that everything inside was working well.
The large cylindrical base of the radio was made out of two thick 15mm thick MDF rings with an external diameter of 180mm and an internal of 140mm. Above and below were two 5mm thick MDF circles of 180mm diameter.
The base has a 55mm diameter hole drilled centrally to house the speaker cone which was later finely sanded to fit well and glued gunned in.
The top has a 60mm hole centrally so that the electronics from below can be wired up through the middle housing. On the left hand side of the top cover there is a 10mm hole for my fm/a, toggle switch (however this may vary depending on what switch is used), a 5mm on the right for the ariel to be thread through from underneath and a 23mm hole centred at the front. The position of this will vary depending on where the circuit board below is actually positioned.
To position the circuit board I cut into on side of the base housing. I had to spend a while measuring it accurately so that i could position the tuning dial in the right place externally as the tuning dial has not been taken for the board.
Step 4: The Upper Housing
This section is built the same way as the base was layered. Cut six 100mm cylinders on 12mm MDF. Four of these should be hollowed into rings with an inner diameter of 60mm and the other two an inner diameter of 80mm. This forms the upper housing for half of the electronics from below to be extended up into and space for the key insert to slot well into.
Step 5: The Key Insert Body
I started off by making a mock up from scrap MDF to check all the dimension were right.
Using 12mm MDF again, following the same format as the other parts of the casing cut 4 x 60mm circles, 3 with a hollowed 40mm inner diameter and one left whole.
For the top half cut 3 x 100mm cylinders , 2 with a hollowed 80mm inner diameter and 1 with a 40mm inner diameter.
To make the battery pack accessible screw a 100mm diameter circle, on 2mm MDF, to the top. This is ideal as it does not add extra unnecessary wood to the key but will conceal the inner batteries and wires.
For the bottom section I designed an extruded 'plus' to insert inside an identical hollowed cut out, kept within the radio. When they are placed within one and other they connect the battery wires to the wires coming from the under body via flat conductive metal pads. The plus has two long narrower opposite lengths and two opposite shorter and wider lengths. The reason for this design was to create a groove that would catch when inserted turning the mechanism below but also eliminating the 50/50 chance of the positives and negatives touching the right pads if the plus had been perfectly symmetrical. Instead the longer sides deal with the positive wires and the shorter with the negative wires, that have been forked from the single battery wires.
The dimensions of this 'plus' are in the final photo. The hollowed part has to be slightly larger than its insert so it fits smoothly, do this by careful sanding to get the perfect fit.
Drill four 2mm holes, one through each edge from inside the key to the base, so that the wires can be threaded through in the next stage.
Step 6: Key Electronics
The dimensions of the key slot internally, leaves enough room to use the battery housing from the original Sony radio. Cut it out from the radio and carve down to size enough to hold the batteries in place and slide into the cylindrical housing. From then solder two wires from each battery output and wire the corresponding wires to the opposite sides of the 'plus' on the base. For my conductive metal I used pre soldered pads bought from Maplins (have posted the link below). Using wire cutters, I cut them to the size of the plus ends and glues them down solidly to the outside of the key base.
Step 7: Key Internal Inset
Rather than trying to create a perfectly shaped cross hollow in the middle of a bit of wood I cut my insert in two separate identical pieces then glued them together which proved to be easier. It also meant that I could make it slightly larger as it was easier to sand in two bits.
For this i followed the same process as before sticking the pads inside the grooves and drilling out the sides from the brass.
This was all mounted on a small 60mm circle of 2mm MDF to be more easily attached to the top of the volume component.
Step 8: Volume Component Housing
I used the original volume dial and cut an identical sized dial from plastic which I bound with epoxy resin. Then cut a central hole to thread the original screw through and make sure the control was solid. I used to back of the speaker cone to centrally mount this housing which worked perfectly and doesn't affect the sound quality at all.
Step 9: Key to Volume Conversion
I used an epoxy resin to bind the bottom of the 'plus' mechanism to the extruded top of the volume component to make sure the bind was strong enough to take the force from the twisting motion. Providing the dimensions have all been cut accurately it should sit at the perfect height for the key to slot into when inserted.
Step 10: Finishing Elements
To finish off use an epoxy resin to extend the tuning dial up from the inner mounted circuit board to the surface of the radio.
Wire up the ariel and fm/am switch pushing them through the pre cut holes, which hold them tightly in place.
Add sticky pads to the underside of the radio to raise the speaker from the ground stopping damage and boosting the acoustics of the radio.
Step 11: Final Product
The final result turned out very well, after final tweeking of the wiring and volume control I managed to get my hacked radio working just as well as the original radio. Mounting the speaker on the bottom of the body facing downwards also seemed to boost the acoustics of the radio. I hope you have enjoyed my first instructable and would really appreciate comments and feedback.