| 摘要 |
<p>An apparatus for indicating the lapse of a predetermined time period compises an indicator element (7), which changes from a first state to a second state when an electrical potential difference is applied to it and reverts to the first state when the potential difference falls below a given value, in combination with a circuit with a bleed resistor (9) for controlling as a function of time a potential difference, applied to th indicator element (7). A cell (1) may apply the potential difference. After a certain period of time the cell (1) will be effectively discharged through the bleed resistor (9), the potential difference applied to the indicator element (7) will fall causing it to change state and sign (8) will then be visible. This indicates the end of the time period.</p> |
