STK4241V Thick Film Hybrid IC AF Power Amplifier (Split Power Supply) (120W+120W min, THD = 0.08%).
Features
• Muting circuit built-in to isolate all types of shock noise
• Current mirror circuit for low 0.08% total harmonic distortion
• Pin compatible with the STK4201II series (THD = 0.4%) and the STK4141X series (THD = 0.02%)

The 74HC/HCT4060 are high-speed Si-gate CMOS devices and are pin compatible with “4060” of the “4000B” series. The 74HC/HCT4060 are 14-stage ripple-carry counter/dividers and oscillators with three oscillator terminals (RS, RTC and CTC), ten buffered outputs (Q3 to Q9 and Q11 to Q13) and an overriding asynchronous master reset (MR).

This circuit react in presence of any conductor object including humans. This circuit does not detect object movement but can act as an proximity sensor!
Sensitivity is adjustable with P1 which will be located at a great distance from the rest of the presence detector circuit.

This is a very simple liquid detector that use a relay to open an evacuation van. You can use it for water or any liquid that conduct electricity. Use any PNP transistor that can stand the relay current. Check out the new water level sensor circuit.