HELP WITH LOGIC CIRCUIT

[NCFC1950]

Hi, pretty much a beginner with logic circuits and have had a crack at it but can only fullfill 3 of 4 conditions. I’ve attached a diagram so hoping someone can help me.

Basically I have 2 float switches at top and bottom of a container and need to switch a pump on when the level reaches the top switch and keep it on until the level falls below the bottom switch then turn the pump off. TIA.

 

[danadak]

Take a look at :

Latching Relay: What is it? (Circuit Diagram And How it Works) | Electrical4U

A SIMPLE explanation of Latching Relays. Learn what a Latching Relay is, how a Latching Relay works, and a Latching Relay circuit diagram. Also known as impulses, bistable, keep, or stay relay ...

www.electrical4u.com

https://www.ibiblio.org/kuphaldt/socratic/output/relay2.pdf

Regards, Dana.

 

[gerritv]

Assuming you are implementing this using a controller, draw a State diagram. States are Empty, Filling, Full.
Initial state is Pump Off.
Empty to Filling event is B going to 1, nothing happens. State is now Filling.
Full State entered from Filling State when A=1, turn Pump On.
Empty State entered again when A=B=0, turn Pump Off.

See https://github.com/jrullan/StateMachine for a typical libray to build this with.

Inside the code where you monitor the switches, you need to track what state the system is in. Change state depending on condition of switches relative to the State.

Gerrit

 

[ZipZapOuch]

Your case 2 and case 4 are the same. You are just describing them differently. If each switch (sensor) only has two states (on/off) and you have two switches (sensors), the most states you can have is 2 squared = 4.

 

[gerritv]

I only listed 3 states, Empty, Filling and Full. I should have worded the first sentence as just initially pump is off.

Initially Pump is off, State is Empty.
When Switch B goes to 1, set State to Filling
When Switch A also goes to 1, set State to Full, turn on Pump.
When Switch A goes to 0, do nothing.
When Switch B also goes to 0, set State to Empty and turn off Pump. (code would be something like If State=Full and A=B=0, then set State to Empty, turn off Pump.)

gerrit