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two proximity sensors, One LED light for system status

two proximity sensors, One LED light for system status

two proximity sensors, One LED light for system status

Hey guys, I am looking to use two proximity sensors to indicate position of two devices (open and closed). Each device will have it's own proximity sensor. I would like to use ONE LED light to know the status of the system (open = green, closed = red, 1 open 1 closed = red)

When the devices are open the proximity sensor from each device will sense a steel part corresponding to that device that is close to it, which I would then like to light up the system LED light green. When the devices are closed, the steel parts are not within range of the proximity sensors, I want the same LED to be red.

If one of the devices is malfunctioning and is still closed while the other device is open, the LED should be red.

My question - is this possible to do with a proximity sensor and LED lights that are common in the automotive (trailer) market? If so, can you guys help me out w/ what this circuit would look like? Or am I getting into some programming and controllers to accomplish this? I could use two LED lights if that would make this significantly easier or less costly (one for open, one for red or malfunction). Apologies for being a noob w/ circuits / electrical systems!


This is an LED I found that shows two color modes - one wire for each. I am thinking that perhaps my system could trigger a switch (via proximity sensor output) when open or closed. When open, the wire for one color is hot, when closed, the wire for the other color is hot. How far off am I.... dazed


RE: two proximity sensors, One LED light for system status

You are looking for the logical operation called AND, as it sensor 1 AND sensor 2 must be in the green state to light the green LED.

Use a pair single-pole, double throw, relays with the outputs wired as follows.

The Normally closed contacts (NC) will be wired in parallel to the Red LED. That way if either one is not getting the Green signal the other will still provide continuity to light the Red LED.

The Normally open contacts (NO) will be wired in series to the Green LED. That way only if both are getting the Green signal will they supply continuity to light the Green LED.

Each relay operating coil will be in series with the output of the appropriate sensor.

RE: two proximity sensors, One LED light for system status

I suggest that OP starts with a "truth table" which is a tabular description of each possible state and what happens with each LED. From then there are simple operations to determine the logic gate(s) required.
https://faculty.etsu.edu/tarnoff/ntes2150/statemac... is an example

TTFN (ta ta for now)
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