It uses a very small photodiode ... power budgets. The detector circuit uses a miniature solar cell and a JFET wired up in a small brass tube to block most of the light and to offer some EM ...

The photodiode and detector control the capacitive discharge ignition system for the engine. The photodiode emits light at a single frequency. When this light is reflected from a coupon attached to ...

But powdered milk is, at least to the limit of detection of ... briefly flooded with UV light, charging up the putatively phosphorescent compounds within. A high-speed photodiode is then used ...