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Water Detector With Sump/Bilge Pump Controller

2015-03-02 04:37  
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This moisture detector with pump controller is built around the special purpose LM1830 IC. The LM1830 is designed to detect moisture by passing an AC current through a set of probes. An internal comparator compares the resistance of the probes to an internal reference. When the resistance between the probes is low (indicating the presence of water or other conductive liquid) then the IC triggers it's output. An AC signal avoids electroplating and corrosion problems that are common when DC is used. To provide an adjustable delay hysteresis to avoid cycling the pump, a timer based around the 555 is used a range of about 5 seconds to two minutes. In this way the pump will stay active for a set amount of time even if the fluid level is below that of the probes.



Scheamtic of the water detector with pump controller



Total Qty.
R11470 Ohm 1/4 W Resistor 
R2, R4110K 1/4 W Resistor 
R316.8K 1/4 W Resistor 
R511 Meg Linear Taper Pot 
R6151K 1/4 W Resistor 
C11470uF 35V Electrolytic Capacitor 
C210.001uF Ceramic Disc Capacitor 
C310.05 uF Ceramic Disc Capacitor 
C4120uF 35V Electrolytic Capacitor 
C516.8uF 35V Electrolytic Capacitor 
C6, C820.01uF Ceramic Disc Capacitor 
C71100uF 35V Electrolytic Capacitor 
U11LM1830 Fluid Detection IC 
U21555 Timer 
Q112N5305 NPN Power Transistor 
D1, D221N4148 Signal Diode 
D311N4002 Rectifier Diode 
K11Relay With 12V Coil (See Notes) 
S11SPST Switch 
PROBES1Stainless Steel Probes (See Notes) 
MISC1Case, Knob, Board, Wire, Sockets For U1 and U2 



The probes should be made of stainless steel and mounted in a non-conductive fixture. Stainless steel nails, bolts or welding rod will make ideal probes. Good non-conductive materials are Lexan, plexiglass or plastic. The probes are to be placed at the liquid level at which you wish the pump to turn on.K1 should be chosen according to the requirements of the pump. If you are running a 12V pump then common automotive relays will work fine. If you are running a mains powered pump then you will need to make sure the contacts are rated accordingly.S1 provides a manual pump switch.R5 adjusts the on-time of the pump once moisture has been detected. It is adjustable from approximately 5 seconds to approximately 2 minutes.The probes should be cleaned periodically to assure reliable operation.


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