S U S T A I N A B L E     T E C H N O L O G Y     E D U C A T I O N     P R O J E C T
home  |  about Practical Action  |  contact us  |  site map  | 
The materials on this site are no longer being updated. For Practical Action's main school site go to www.practicalaction.org/schools

Inventing the clockwork radio

Product analysis

This product analysis focuses on the most recent clockwork radio design - the Freeplay 360.

The market
The Freeplay 360 has been designed to extend the clockwork radio market into countries like the UK. The radio's styling, size and functions make it particularly suitable for:

However, the radio is not ideal for use outside (unlike the original version aimed at the African market). Rain can easily enter the product through gaps between the casing, switches and headphone sockets. The casing material scratches easily and is likely to break if dropped on a hard surface.

Technical specification
Power rating: 3 volts at 30mA (0.03A)
Frequency ranges: 88-108MHz FM; 520-1700KHz
Dimensions: 210 x 104 x 74mm
Weight: 1kg
Cost: about 50 (in the UK)
Life in service: at least 10,000 turns of the spring

Product function
The radio receives AM and FM radio signals and amplifies them to produce a good-quality output.

Like all wind-up radios, the Freeplay 360 can be powered by turning a handle to wind a coil spring onto the main drive axle. About 60 turns of the handle fully energises the spring, powering the radio for six to eight minutes. A clutch mechanism ensures that the handle is turned in the right direction without moving the gear/pulley system. The potential energy stored in the spring is then converted into kinetic energy to drive a generator, which in turn powers the radio circuit.

The radio has three other possible energy supplies:
Materials From an environmental point of view, the radio is largely made from recyclable materials. Similarly, its packaging is made from recycled or recyclable cardboard, polythene and expanded polystyrene.

The product can be assembled quickly and easily by unskilled workers, keeping manufacturing costs down.

Self-tapping screws hold the casing, circuit board, aerial, generator and handles together. Control knobs push onto the variable resistor/capacitor shafts and small gears fit onto the large gears using interference fits. The speaker cover is attached by bending over fixing tabs that pass through the front of the radio casing. The speaker clips into the casing without the need for adhesives or screws.

The risk of electric shock from the radio is low, as it uses an external transformer and there are no exposed metal components.

The most hazardous part of the radio is the spring, which is very powerful when energised and could cause serious injury if allowed to unwind in an uncontrolled way. To minimise this danger, the spring is housed in a tough plastic casing and the radio casing is fitted with tamper-proof screws. A label on the product states that repairs should only be carried out by an authorised dealer.

Hazardous chemicals that can produce toxic fumes are used in the manufacture of the radio circuit and casing. The storage and use of these chemicals is carefully controlled and fumes are extracted to ensure a safe and healthy environment for factory workers.

The radio is heavy because of the weight of the spring, but is quite evenly balanced and has a simple carrying handle.

The controls are easy to find and are labelled with symbols and clear lettering. More grip would be helpful on the tuner control.

The length of the crank handle makes it easy to wind the spring.

The most attractive element of the radio is its transparent plastic casing (reminiscent of the Apple iMac computer). Three colours are available - black, blue and clear.

The speaker cover has been enlarged to hide some of the less interesting internal components and unsightly axles. Graphics used on the product are there to convey information rather than for decoration and have been screen-printed onto the casing in white and yellow.

next page »



print this page back to top
Practical Action - Technology challenging povertyEuropean Commission - Department for International Development

S U S T A I N A B L E     T E C H N O L O G Y     E D U C A T I O N     P R O J E C T