| 摘要 |
The 120 volt AC is changed to 24 volt AC through a 24 volt center tap 1 amp transformer to provide two 12 volt sources which goes to two bridge rectifiers to supply two sources of 12 volt DC. The first rectifier which supplys 12 volts to a 12 volt DC 2 amp 2 pole 2 throw relay through the contacts of a 24 volt AC 5 a 3 pole 2 throw relay. The 24 volt AC relay is turned on by the reset switch which is normaly open. This switch supplys 24 volts to the 24 volt AC relay when the 24 volt relay energizes, one set of contacts energize the 12 volt DC relay, the second set of contacts turns on whatever is plugged into the 120 volt AC outlet. The third set of contacts latch the 24 volt relay to stay on. When the 12 volt DC relay is energized it supplys 12 volt DC to the electrolytic capacitor 2200 uf@ vDC which puts a 30 ms pulse on the water valves causing the water valves to open. When water touches the sensor, a current flows through a 22k ohm 0.25 watt resistor to the base of transistor mps4124 turning on the transistor mps4124 this in turn,turns on transistor c638 ph00 which supplys voltage to the gate of the track bt a06 400t causing it to open the circuit to the 24 volt AC relay. This opens the contacts to the 12 volt DC relay causing the 12 volts to be reversed to the capactor causing a 30 ms negative pulse to be applied to the water valve. This causes the water valve to shut the water off. At the same time another set of contacts in the 24 volt AC relay opens a circuit to the device that is plugged into the AC outlet.The bridge rectifier ecg 166 supplys 12 vDC to the pulse circuit resistor 470 ohm 1 watt and transistor c2834a npn regulates the 12 volt DC and the electrolytic capacitor supplys the current needed for the positive and negative pulse. The positive voltage is supplyed by a resistor 100k ohm 0.25 watt and the negative voltage is supplied by a general purpose rectifier ecg125. The lamp 28 volts bayonet base is connected to the energizing coil of the 24 volt AC relay, this lamp is on when the 24 volt AC relay is on supplying power to the AC outlet.
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