The choice of dynamo is left up to the user. Many different models are available at various prices . As a rule, the expensive ones may not provide more output, but are more robust and will therefore last longer.
Most dynamos are rated at 6 volts 3 watts. However the output varies considerably with speed. Some dynamos, usually the more expensive ones, are fitted with zener diodes. These are small electronic components which limit the output of the dynamo above a certain speed. A zener diode will inhibit the operation of the VeloCharger, and if fitted they MUST be removed. Fortunately this is usually a fairly simple operation. The zener diode is normally fitted in the base of the dynamo, which is clipped to the body or held with screws. Once the base is removed, the zener diode can be seen as a small black component with a lead at each end. It can then be cut out quite easily.
Suitable dynamos are available from a variety of sources, including Amazon, SJS Cycles, and Rose Bikes. Brackets to fit the dynamo to your bike are also available from these suppliers. The choice of bracket will be dictated to some degree by the type of bike and the diameter of the tube to which the dynamo is to be fitted.
In the picture to the left, I have used Rose Bikes “Xtreme bandage” clamps, together with a Thorn dynamo boss from SJS. This gives a secure and adjustable fitting.
Among the dynamos which have been tested are the Busch & Muller Dymotec 6 and the Axa Basta Quattro. Both these have easily removable zener diodes.
However you fit your dynamo, it is most important to ensure that it faces forward of the tube it is fixed to. This is so that if it works loose, it will be pushed away from the wheel rather than being jammed between the tube and the spokes, causing a sudden stop.