| 摘要 |
The appts. includes a relay, which when carrying 12 volts, passes 220 volts. When a second relay has 12 volts through it, the current through the pump is interrupted. Two electrodes are used for protection against flooding, and are located on the inside of an outer plant pot. other electrodes used involve the current in the ammeter not rising to the point where relays switch off the pump. The central electrode remains conductive at the same time as the other two, and sends an extra current through the ammeter. - Hoses connect to all plant or flower pots and pumps deliver water containing a weak fertilizer solution from a suspended tank. Rotary resistances are used so that the current through the ammeter and the plant pots can be varied. All electrodes are aluminum rods 4-5 mm dia. and with a length of approx. 12 cm.s cms. (Provisional basic advised week 85/09)(0/1) |
