Specifications
CONSTRUCTION
RUPANJANA
ELECTROLYSIS-PROOF COMPLETE
WATER-LEVEL SOLUTION
O
ne major problem in using wa-
ter as a conducting medium
arises due to the process of elec-
trolysis, since the sensor probes used for
level detection are in contact with water
and they get deteriorated over a period of
time. This degradation occurs due to the
deposition of ions on the probes, which
are liberated during the process of elec-
trolysis. Thereby, the conductivity of the
probes decreases gradually and results in
the malfunctioning of the system. This
can be avoided by energising the probes
using an AC source instead of a DC
source.
The circuit presented here incorpo-
rates the following features:
1. It monitors the reservoir (sump
tank) on the ground floor and controls the
pump motor by switching it ‘on’ when the
sump tank level is sufficient and turning
it ‘off’ when the water in the sump tank
reaches a minimum level.
2. Emergency switching on/off of the
pump motor manually is feasible.
3. The pump motor is operated only if
the mains voltage is within safe limits.
This increases the life of the motor.
4. It keeps track of the level in the
overhead tank (OHT) and switches on/off
the motor accordingly automatically.
5. It checks the proper working of the
motor by sensing the water flow into the
tank. The motor is switched ‘on’ and ‘off’
three times, with a delay of about 10 sec-
onds, and if water is not flowing into the
overhead tank due to any reason, such as
air-lock inside the pipe, it warns the user
by audio-visual means.
6. It gives visual and audio indica-
tions of all the events listed above.
7. An audio indication is given while
the motor is running.
8. The system is electrolysis-proof.
Description
The power supply section (Fig. 1). It
LOKESH KUMATH
comprises a step-down transformer (with
secondary voltage and current rating of
15V-0-15V, 1A respectively), followed by
a bridge rectifier, filter, and 12-volt regu-
lators [LM7812 for +12V (V
CC
) and
LM7912 for –12V (V
EE
)]. Capacitors C1-
C4, across rectifier diodes, and C8 and
C10, across regulator output, function as
noise eliminators. Diodes D5 and D6 are
Fig. 1: Circuit diagram of complete water level solution (contd. refer Fig. 2)
45