This is a project of a simple static electricity detector using CA3140 IC. The circuit is very sensitive and can detect charge from distance of one or two meters. It can also be used variety of other purposes for example as an electric field detector for detecting the presence of electric current in electric wires
without touching them with millimeters or related equipments. It can also be used as an ion detector etc. You can also do variety of experiments with this circuit to find what this little circuit can do.
The circuit is simple to build and using not more the six components including the IC. The heart of the circuit is a CA3140 IC that is a high performance operational amplifier IC. The output of the IC is fed to the 2N4401 transistor that is driving an LED.
The CA3140 IC detects and amplifies the static charge around the antenna. The amplified signal is available at the output pin 6 of the IC and fed to the transistor due to which the transistor conduct and LED become activated. The operating voltage of the circuit is 9 to 12 volt DC but it can also be operated with 6 volt DC. The antenna can be an 8 inch piece of hard wire which can able to stand vertical in the air.