| 摘要 |
The monitor (10,11) as the result of probing different depths of soil, adopts different values for an electrical property, e.g. resistance, capacitance impedance or electromotive force, dependent upon the humidity content of the earth. A further monitor comprises an electrical signal (21) with a measurement instrument which emits an electrical signal, pref. voltage, dependent upon the value of the monitor electrical condition. The main monitor comprises two groups (10,11) of components fitted on the machine and in engagement with the soil. At leastone group (10) is insulated electrically from the machine or tool body, and the two groups are electrically series-connected, forming part of a branch (21) of an electrical bridge coupling. The signal emitted by the measurement instrument is conducted to an indicating instrument calibrated so that the humidity at the actual working depth is shown. |
