Circuit Diagram
Description
The automatic pump controller eliminates the need for any manual
switching of pumps installed for the purpose of pumping water from a
reservoir to an overhead tank (refer Fig. 1). It automatically switches
on the pump when the water level in the tank falls below a certain low
level (L), provided the water level in the reservoir is above a certain
level (R). Subsequently, as the water level in the tank rises to an
upper level (M), the pump switched off automatically. The pump is turned
on again only when the water level again falls below level L in the
tank, provided the level in the reservoir is above R. This automated
action continues. The circuit is designed to ‘overlook’ the transient
oscillations of the water level which would otherwise cause the logic to
change its state rapidly and unnecessarily. The circuit uses a single
CMOS chip (CD4001) for logic processing. No use of any moving
electro-mechanical parts in the water-level sensor has been made. This
ensures quick response, no wear and tear, and no mechanical failures.
The circuit diagram is shown in Fig. 2. The device performed
satisfactorily on a test run in conjunction with a 0.5 HP motor and
pump. The sensors used in the circuit can be any two conducting probes,
preferably resistant to electrolytic corrosion. For instance, in the
simplest case, a properly sealed audio jack can be used to work as the
sensor. The circuit can also be used as a constant fluid level
maintainer. For this purpose the probes M and L are brought very close
to each other to ensure that the fluid level is maintained within the M
and L levels. The advantage of this system is that it can be used in
tanks/reservoirs of any capacity whatsoever. However, the circuit cannot
be used for purely non-conducting fluids. For non-conducting fluids,
some modifications need to be made in the fluid-level sensors. The
circuit can however be kept intact.
Source -: http://www.electronics-lab.com
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