Set/Reset on a 4013

[captainkirksdog]

Hi,
I have a problem with my design and I need some input.

S1 is located near the bottom of a half-full tank of water. S2 is near the top. At power-up, S1 is CLOSED, S2 is OPEN. When the water rises to close S2, the pump needs to turn ON. It should stay ON until the water level drops to open S1. The pump should then remain OFF until the water rises to close S2. Repeat as necessary.

I have come up with designs for water sensing, motor-control, and a power supply, but I keep getting stuck on the logic. Can I use the Set/Reset inputs on a 4013 to do this? With some NAND conditioning on the inputs, shouldn't this work?

Attached is a .gif drawing. Thank you.

 

[laroche73]

water level pump circuit

It looks like it should work, have you tried it out yet? You could simplify things a little by getting rid of the 4013, and making a cross-coupled latch out of the 4011 NAND gates. The latch has a disallowed state (both inputs at logic "0" for the NAND version, both at logic "1" for a similar latch made out of 4001 NOR gates ). Inverting the output of S1 bypasses the disallowed state, since S1 is never off when S2 is on. S1-Off/S2-Off resets the latch, S1-On/S2-On sets it, and there's no change during the S1-On/S2-Off state.

The latch can power up in either state when the water level is between S1 and S2. This could be an issue, since the pump could come on at power-up until S1 shuts off. Wiring S1 to the positive supply and using R2 as a pulldown would eliminate the inverter, though low-side switching is a better idea in case a short develops somewhere in the wiring.

You could use a schmitt-trigger NAND like the 4093, but there's no real need to, since the water level provides plenty of hysteresis.

 

[laroche73]

Adding POR to NAND latch

The last circuit I posted has the disadvantage of powering up in the "hold" state when the tank is half-full, i.e. it could initially be "set" or "reset". The circuit below uses a triple input NAND like the CD4023 along with a power-on RC to bring up the latch in its "reset" state when the water level is between S1 and S2.

 

[M.Shoaib]

Simple Automatic Water Pump Controller

This is Simple DLD( Digital Logic Design Project).
This Project Control water Pump automatically.
see attach file

 

[mbarazeen]

This is Simple DLD( Digital Logic Design Project).
This Project Control water Pump automatically.
see attach file
View attachment 50849

you have replied to a very old post