It is available in three configurations, including powersupplyboard only, a board with a plug-in transformer, or a board with an enclosure and a plug-in transformer.
它有三种配置，包括电源板，插件变压器板和一个插件变压器。
2
Nuclear submarines are able to provide their own infinite supply of air, water and power. Their only limitation for staying submerged is the amount of food on board.
核潜艇可以无限止地供应空气，水和动力，唯一对潜水时间有限制的是艇上的食品储量。
3
Providing an on-boardpowersupply is difficult, however, so he is investigating the use of external magnetic fields to power the device.