Electronic Water Pressure Switch Circuit

A water pressure switch is designed for sensing pressure of an incoming water flow from a source which may be a booster pump, and compare it with the water pressure inside the tank which is being filled by the booster pump water flow. When the water pressure inside the tank crosses the set threshold relative to the pump pressure, an in-built switch is tripped. The trip switch is configured with the booster pump electrical such that when it trips, the motor halts and prevents the tank from filling above the desired upper threshold. A reverse action is initiated as soon as the water level in the tank reaches below a certain lower threshold.

Pressure switches are normally mechanical with their operations, and may not be easy to build or replicate at home by a hobbyist. Even an electronic equivalent of the same which might require a precise pressure sensor could be difficult to implement due to the many intricacies of the system.

However a simple alternative for fulfilling the above specified functioning of a pressure switch could be replicated with the help of the following shown electronic set up.

In the design we can see a small PVC container which could be a piece of plastic pipe cut into an appropriate size for the purpose.

A small water inlet derived from the main booster motor water supply is injected into the container and allowed to be filled and its level monitored relative to the main tank.

The container is required to be dimensioned such that the accumulated water level inside it proportionately corresponds to the water level of the main tank.

The upper threshold of the main tank and the container are monitored and the position marked over the container precisely corresponding to the upper cut-off threshold of the main tank.

This position is marked and fitted with a reed relay on the outer side of the container.

Another reed switch is clamped at the bottom of the container intended for the lower level switch ON purpose.

The inside of the container consists of a float embedded with a strong neodymium magnet, this float is intended to float upwards and downwards with the the water's rising or declining levels inside the container.

The above action in turn is intended to interact with the adjoining external reed switches creating a toggling response in them.

The reed switch contacts are integrated with a simple set-reset circuit as shown above. This set/reset latch configuration consists of a relay which is to be wired up with the booster motor electrical.

Referring to the above controller circuit, when the water level is below the lower reed switch, it toggles the circuit and sets the relay into a switch ON position activating the connected motor.

The motor starts pumping water into the tank and when the tank level reaches the maximum threshold the container level also correspondingly rises to the set upper level triggering the relevant reed switch2, which instantly switches OFF the motor.

The circuit keeps the situation latched until the water level has yet again reached the lower threshold of the main tank as and the container. The cycle is repeated consistently maintaining the desired quantity of water in the tank and preventing the motor from incorrect triggering and burning.