Home Made Geophone Detects Foot Stomp Circuit

This is a design circuit for geophone detector circuit that can be use in home. Here’s the figure of the circuit;

This circuit is made from a strong magnet, a coil of wire and a rubber band. The circuit is sensitive enough to detect the vibrations of a nearby foot stomp.  It could be used as an earthquake detector.

Dual Liquid Level Sensor Circuit

This is a design circuit for dual liquid level detector. Here’s the figure of the circuit;

This circuit is use CA3410 quad BiMOS op amp to sense small currents. Because the op amp's input current is low, a current of only 1 μA passing through the sensor will change the converter's output by as much as 10 to 12 V. [Circuit diagram source: seekic.com]