In my novel, which I hope to publish this year, I have the concept of a talker. My illustrator asked me what such a device looks like, and I decided to try to make a raytrace of one, which you should be able to see. A talker is basically a steampunk version of a cellphone. It doesn't use electricity, instead it uses a combination of air pressure (stored in a tank, and increased using a manual pump, similar to that of a blood pressure meter) and phosphorus, which is charged in sunlight. The description in my technology document is as follows:
Transmitting: The talker has a light source (portable ones use a phosphor compound, which charges as long as it is exposed to light, wall mounted talkers usually use a friction light). When in use, the vibrations of the speaker cause a small mirror to vibrate, causing the light to change in amplitude. The crystal shape changes this light into a beam, which can be sent over a distance.
Receiving: When a beam hits a crystal anywhere, it is captured, and using the structure of the crystal aimed at a tiny metal valve that expands and contracts based on the amount of light (when there is no light, the valve is closed). The valve allows air to flow from a pressure chamber (manually inflated using a small pump in portable talkers, using a continuous pump for wall mounted versions) into a hose that ends in an ear piece, which allows the receiving party to hear the voice.
Signalling: Certain wavelengths will not be aimed at the valve by the crystal, but instead will cause the crystal to glow in a particular color, indicating in incoming call, or show other important information.
Switching: The large crystals mounted on top of mountains are connected to glass pipes, linking to exchanges, where operators receive the calls and redirect them to other talkers or to other exchanges using glass rods.
In the device on the picture you can see the green crystal (with the light green light of the phosphorus behind it), the mirror, the rubber ball used to pressurize the copper tank, the valve under the lens under the crystal, the blackish rubber tube leading to the ear piece, which can be attached to the side of the tank when carried. There is also a hook that allows you to hang the talker from your belt. The most important component of the talker is the crystal, which has four tasks.
1. It needs to convert incoming light into heat, using a lens that is attached below the crystal. The heat operates a miniature valve that responds rapidly to these heat changes, and allows minute amounts of air to escape from the reservoir depending on the amount of heat (or light). Diffuse is filtered by the crystal, and never reaches the valve.
2. It receives light from the phosphorus via a mirror. The mirror is mounted on top of the reservoir, aimed at the phosphorus and the crystal. Two springs hold the mirror at an angle at which it is at the verge of sending light to the crystal. When the mirror vibrates, the mirror will reflect the phosphorus on the crystal, which will turn it into a parallel beam emitted in a specific direction.
3. When parallel light of a certain wavelength is received, the crystal will light up. This allows the user to ensure correct alignment (the crystal is able to correct for certain variations, but aiming is important). For stationary talkers this ability is used to alert a user that there is an incoming call.
4. Diffuse light is gathered and aimed at the phosphorus, allowing it to charge when not in use.
