# Digital circuits design

Discussion in 'Homework Help' started by ahsanjamal, Oct 26, 2010.

1. ### ahsanjamal Thread Starter New Member

Oct 26, 2010
1
0
hi.

I have to make a project for detecting water level with the help of basic digital gates...Please i need guidance and all information to build a water level sensor.

2. ### Papabravo Expert

Feb 24, 2006
11,137
2,175
I don't think digital gates by themselves will do the job. What ideas do you have for sensing the presence or absence of water?

3. ### PRS Well-Known Member

Aug 24, 2008
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You're being asked to use a preexisting transducer or develop your own. To develop your own make use of a changing electrical entity -- voltage, current, or resistance -- that changes with your water level. He's one off the top of my head. For a water level that changes one foot, use a float and an arm in a toilet bowl and have that arm move a potentiometer. Using that pot in a circuit, it can vary the voltage, and the voltage can be read by a voltmeter. The voltage is thus proportional to the depth of water.

In a similar design example, I used a spring to measure a weight between 0 and 10 pounds. The spring was the type that is normally closed and is opened with a force. I hung a weight basket from a rod attached to the spring, but enclosed the spring and part of the rod inside a PVC pipe. Then I fixed an IR photo-transistor to the rod and a photo-resistor to the inner wall of the pipe and the result was a current that varied with the distance of the LED and photo-resistor. This was used in a circuit to measure weight based on displaced distance.

There are many ways to go about it. As for your digital circuit there are various ways of going about that. An ADC comes to mind, this being an MCU project. But before getting into the nuts and bolts, what is the change in the depth of the water you are measuring, and what resolution do you need? An inch? A foot? We need more parameters in order to come up with a practical approach.

Last edited: Oct 26, 2010
4. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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What is the output of the logic supposed to be? (Relay, LCD or LED Display, other, etc)

Have you worked with logic before?

Is the water pure enough to use sensors in contact, or sewage?