The pcb tracks can be designed in such a way that a full tank gives high resistance and an empty tank gives low resistance or vice versa.
Reed switch sensor circuit.
A reed switch switches a current on the same way but a magnet provides the pushing pressure instead of your finger.
A push to make switch makes a connection and completes a circuit when you push it in.
A reed switch is a sensor that closes the circuit in the presence of a magnetic field.
A reed switch is a very basic 2 lead switch that is switched on by a magnet being brought into the vicinity of the switch.
The contacts are usually normally open closing when a magnetic field is present or they may be.
There are normally open reed switches and normally closed reed switches.
The reed switch is an electrical switch operated by an applied magnetic field it was invented at bell telephone laboratories in 1936 by walter b.
Reed switches and reed sensors are used along with resistors or special reed sensors with integrated resistor to give out a potentiometric feed back across two outputs as a foamed magnetic float moves along the pcb s length.
Reed sensors can be used in many applications where contactless on off is required.
A spring makes it pop back out again when you take your finger away.
Simply put it is a magnetic switch.
There are 2 basic types of reed switches.
Capacitive loads as low as 50 pf which could even be caused by the wiring between the reed switch and the load could enough to reduce the life.
In its simplest and most common form it consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope.
How to build a reed switch circuit.