Using the LM3914 and LM35 temperature sensor can be designed various electronic thermometer projects . The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature.
This metal detector circuit electronic project is an very simple circuit that is based on common electronic parts . This metal detector circuit electronic project is based on transistors and will provide an visual indication using a LED and an acoustic sound that will inform you when a metal is detected .
A very simple proximity detector can be made using this electronic scheme. This electronic circuit reacts to the presence of a conductive object within a particular field. Circuit sensitivity can be adjusted with potentiometer P1 for the desired distance. The electronic circuit consists essentially of a monostable oscillator and a tipping stage. Oscillator is built with transistor T1. This is why a flap that oscillator frequency is particularly stable, because the capacity of the transistor is in parallel with relatively large capacities C1 and C2 of the oscillating circuit.