Electromagnetic Sensor Circuit Using 741 IC

This is a design schematic to sensor the electromagnetic field. This circuit is based or built by 741 IC. This IC is an op-amp. The circuit can detect the field even hidden wrings. This is the figure of the schematic.


A 1mH inductor is used for sensing the electric field. The electric field will induce a small voltage in the sensor inductor and this induced voltage is amplified by the op amp. The headphone connect at the output of the op amp will give an audio indication of the electric field. For example, the electric field around a main transformer can be heard as a 50 Hz hum. The POT R4 can be used to adjust the gain of the amplifier. By keeping the sensor inductor near to a telephone line, you can even hear the telephone conversations. All electrolytic capacitors must be rated at least 15V. The switch S1 can be a slide type ON/OFF switch. The POT R4 can be used to adjust the gain. It is better to have a radial type inductor for L1.

Continue Reading..

Water Level Sensor Schematics

This simple water level sensor circuit monitors the presence of water in a certain location or container. The circuit sends an acoustic alarm when it senses a drop of water leak. It is very simple to build and it is made of a single IC and some passive components. Check out the water level indicator circuit too!

The IC LM1801 is a low power comparator that can deliver high output current if needed. When water hits the sensor, the reference voltage is overshot and the IC drives the ceramic transducer to beep. It is also possible to connect several sensors to the water level monitor circuit. The sensor can be easibly made out of a small piece of PCB that is etched with the proper pattern. The decoupling capacitor C3 is a 100uF/16V electrolytic capacitor. 

source [link] 

Continue Reading..