1. Making a digital Salinometer
Shefalika Prasad
Clarence High School

2. Circuit Design
Idea came from web searching , Daniel Kramnik’s website and then finding the original circuit:

3. Oscillator
AC measures a salt solution conductivity without dissociating it.
AC is generated here by the Oscillator section
10Khz Sine wave at 20 V peak to peak

4. Gain loop
The probe dipped in salt acts as a volume control of a simple Operational Amplifier
The more salt in water the higher the voltage coming to output

5. AC to DC Conversion Allows displaying the output voltage.
Meter is Zero in air or Distilled Water
Meter is at Volts in saturated salt solution full deflection.

6. Designing a PCB using pad2pad

7. Calibrating the meter
Calibration was done by measuring the voltage in known concentration salt solutions.

8. Calibration Curve

9. Making a housing