The sensor wire has to be placed in the vicinity of the mains wire to be tested. When there is no voltage in the mains line, no voltage will be induced in the sensor wire and the display will show a random digit. When there is voltage in the mains line, a small voltage will be induced in the sensor wire due to electromagnetic induction and this voltage is sufficient enough to clock the CMOS IC CD4033. Now the display will count from zero to nine and repeat.

Notes:

• The circuit can be assembled on a Vero board.
• Use 9V PP3 battery for powering the circuit.
• Use a 10cm insulated wire as the sensor.
• The IC must be mounted on a holder.
• Switch S1 can be a miniature ON/OFF switch.

A Salt
intake in large quantities is not good for the body and also causes of
diseases such as kidney disease, high blood pressure, heart disease and
paralysis. We should not eat too much. But the recognition of
salinity, but may differ. Therefore should be a good barometer. I
highly recommend The food salt & salinity tester meter circuit,
because it is simple circuit and cheap too.
The circuit ideals.

We use the comparator circuit by an op-amp IC. Which is the difference
between the volume resistance or conductivity of the solution foods has
salt is constituent. In with sensing probe immersed or dunk in the
water or food. Then Showing amount of salt much, Appropriate salinity,
and a little salinity with 3 different LED colors.

How the circuit works.

The circuit ready running When dipping or dip the probe into the
solution or food. Then press switch-S1, by has IC1/1(LM324) amplify a
differential signal, the voltage output at pin 1 as quantities
resistance or conductivity of the solution foods has salt component is
measured through the probe.
Which if a water or foods with little
salt as an ingredient. The resistance is quite high. Less current to
flow through it. The voltage comparator circuit so has the output at
pin 1 a few, As a result output at pin 14, pin 8 and pin 7 of
IC1/4,IC1/3 and IC1/2(LM324) have all high state, makes the LED5, LED4
and LED3 not glow.
Water or food, that have a salt is very
complement. Resistance is relatively low. Current to flow through much,
makes the output signal at pin 1 much into the voltage comparator
circuit , as a result the output at pin 14, pin 8 or pin 7 of IC1/4,
IC1/3 and IC1/2 has state is high only one or all, makes LED5,LED4 or
LED3 in order to light up.
Additional will use LED5 yellow. If
brightness is represented by the amount of salt. With little food or
water. If the green light is LED4 is represented by the amount of salt
in food or water has Fitted. And the LED3 will light red when the user
is represented by the amount of salt in food or water is too much.