# Is my idea possible?

#### TimothyToolMan

Joined Mar 10, 2022
1
Hello, firstly I am a complete novice with an idea that may or may not be possible, hence I signed up to the forum for help. I would like build a circuit which will light up a green light if, at the moment pressure is released from a pressure sensor, the height of two points A and B are level. The best way I can explain it is imagine you are holding a ball in each hand and at the same time you have your foot on a pressure sensor. When you release your foot from the sensor a green light will illuminate if the balls in each hand are level with each other. It will illuminate red if the balls are not level.

#### MrChips

Joined Oct 2, 2009
26,113
Hello, firstly I am a complete novice with an idea that may or may not be possible, hence I signed up to the forum for help. I would like build a circuit which will light up a green light if, at the moment pressure is released from a pressure sensor, the height of two points A and B are level. The best way I can explain it is imagine you are holding a ball in each hand and at the same time you have your foot on a pressure sensor. When you release your foot from the sensor a green light will illuminate if the balls in each hand are level with each other. It will illuminate red if the balls are not level.
Welcome to AAC!

There is a basic circuit element in analog electronics called a voltage comparator or analog comparator. It compares two voltages and outputs a digital signal 0 or 1. For example, if V1 is less than V2 the output is a low voltage. The output changes to a high voltage when V1 exceeds V2.

Notice that there is no valid test for V1 being the same as V2 because this never happens in the real world when noise is added into the mix.

Using multiple comparators set at different input threshold voltages you can arrive at a solution for your requirements.

#### Ian0

Joined Aug 7, 2020
5,147
How were you thinking of converting the height of the two points into an electrical signal?

#### Ya’akov

Joined Jan 27, 2019
5,663
@MrChips has a good solution. I will just add that you will need some sort of sensor that will measure the position of the two objects relative to each other. Without knowing what you are actually intending it is not possible to recommend one but as an example, if you had a balance arm with the objects on each end you could use a position sensor at the middle.

One more thing is that depending on what you actually want to do, a microcontroller, like an Arduino compatible might be a better route than discrete components.

#### LesJones

Joined Jan 8, 2017
3,707
In your example when you say the balls are at the same height what does that mean. If on is 1 mm higher do you consider them to be at the same height. If one is 0.000001 mm higher than the other do you consider them to be at the same height. In practice they will never be at EXACTLY the same height.

Les.

#### Ian0

Joined Aug 7, 2020
5,147
@MrChips if you had a balance arm with the objects on each end you could use a position sensor at the middle.
That position sensor could be as simple as a rotary Potentiometer

#### Alec_t

Joined Sep 17, 2013
12,812
The more detail you give us the more likely you will get a satisfactory solution.
It would help if you told us what the two objects are, or at least their size and separation. Are they in air or liquid? Any constraints on their movement?
Do you already have a particular pressure sensor in mind?
Would you be able to solder components to build a circuit?

#### BobTPH

Joined Jun 5, 2013
4,907
That position sensor could be as simple as a rotary Potentiometer
Or as sophisticated as a camera / computer vision system. It all depends on the constraints imposed by the actual mechanical configuration.

Why are you hesitant to tell us the actual situation? Is this anorher top secret project that is going to make you a billionaire and you are afraid someone will steal your idea? We get a couple if those a month. Haven’t seen any become a billionaire yet.

Bob

#### MrSalts

Joined Apr 2, 2020
1,762
That position sensor could be as simple as a rotary Potentiometer
How does a rotary potentiometer sense a change in a pressure sensor as the OP requested?

at the moment pressure is released from a pressure sensor,

#### BobTPH

Joined Jun 5, 2013
4,907
I think he was talking about the position sensors
Bob.

#### MrSalts

Joined Apr 2, 2020
1,762
Hello, firstly I am a complete novice with an idea that may or may not be possible, hence I signed up to the forum for help. I would like build a circuit which will light up a green light if, at the moment pressure is released from a pressure sensor, the height of two points A and B are level. The best way I can explain it is imagine you are holding a ball in each hand and at the same time you have your foot on a pressure sensor. When you release your foot from the sensor a green light will illuminate if the balls in each hand are level with each other. It will illuminate red if the balls are not level.
Digital pressure sensors are everywhere (often called barometers). High resolution barometers are on many phones as well and they are accurate enough on most Samsung phones and older iPhones to determine which step you are in as you climb a staircase.

An intern working for me recently looked into the resolution on the iPhone 12/13 and found it is better but could not find an app that could take advantage of the higher resolution barometer.

You should be able to find digital barometers that can help you. With a digital signal, you should be able to set rules by creating a definition of "equal", "above" and "below" once you calibrate the barometer chips on each ball.

#### MrSalts

Joined Apr 2, 2020
1,762
I think he was talking about the position sensors
Bob.
Why did he change the OP's question or topic? How is thst helpful?

#### Ian0

Joined Aug 7, 2020
5,147
Why did he change the OP's question or topic? How is thst helpful?
The TS needs a position sensor so that he knows when his balls are level.

#### MrSalts

Joined Apr 2, 2020
1,762
The TS needs a position sensor so that he knows when his balls are level.
Yes, he knows that. The TS was asking if it could be done with pressure sensors but you somehow think a potentiometer can act as a pressure sensor or you are changing the OP's question (if so, why are you changing the OP's question when a pressure sensor is a reasonable approach until we learn that the OP's definition of "above" and "below" are outside the resolution of a pressure sensor).

Note: read the TS's question, not other member's solutions.

#### Ian0

Joined Aug 7, 2020
5,147
Yes, he knows that. The TS was asking if it could be done with pressure sensors but you somehow think a potentiometer can act as a pressure sensor or you are changing the OP's question (if so, why are you changing the OP's question when a pressure sensor is a reasonable approach until we learn that the OP's definition of "above" and "below" are outside the resolution of a pressure sensor).

Note: read the TS's question, not other member's solutions.
What he said was
“ I would like build a circuit which will light up a green light if, at the moment pressure is released from a pressure sensor, the height of two points A and B are level.”
He does NOT say that the heights of A and B are measured by said pressure sensor.

#### MrSalts

Joined Apr 2, 2020
1,762
What he said was
“ I would like build a circuit which will light up a green light if, at the moment pressure is released from a pressure sensor, the height of two points A and B are level.”
He does NOT say that the heights of A and B are measured by said pressure sensor.
Convoluted interpretation which means the presence or absence of a pressure sensor is irrelevant and the trigger point to measure position (when pressure is released) is irrelevant if you are adding some sort of rotary position sensor that could be active al the time. But, hey, interpret as you wish.

#### Ian0

Joined Aug 7, 2020
5,147
Convoluted interpretation which means the presence or absence of a pressure sensor is irrelevant and the trigger point to measure position (when pressure is released) is irrelevant if you are adding some sort of rotary position sensor that could be active al the time. But, hey, interpret as you wish.
Reading posts 4 and 5 might help you understand that yours is the anomalous point of view.

#### MrSalts

Joined Apr 2, 2020
1,762
Reading posts 4 and 5 might help you understand that yours is the anomalous point of view.
It's not unusual that I am the only one to understand the OP.

#### shortbus

Joined Sep 30, 2009
9,372
The TS needs a position sensor so that he knows when his balls are level.
Mine are when I'm standing on around a 5 degree angle.

#### MrSalts

Joined Apr 2, 2020
1,762
Mine are when I'm standing on around a 5 degree angle.
Always Mr Practical.