How to get an LED to turn on at a certain voltage.

[alexgeo]

Alright, I am completely new to this forum so please excuse me if this question is obvious! Anyways, I'm building a proximity sensor system as a part of a school project and I am trying to use this IR sensor to get this whole thing to work:

https://www.electro-tech-online.com/custompdfs/2010/12/gp2y0a02yk_e.pdf

Basically I need an LED to come on when a object reaches approximately 2ft away from the sensor. Looking at the output graph on the manual, we can see that at approx. 2ft (60cm), the output voltage will be around 1V.

So to sum the question up, how do I make a circuit which turns an LED on when the voltage only reaches 1V and up?

 

[Nigel Goodwin]

Look up a comparator, you can use an opamp as one - or a specific chip.

 

[alexgeo]

Look up a comparator, you can use an opamp as one - or a specific chip.

Ok, I've been researching this for an hour or so, and it sounds like something that would work - but having no experience whatsoever with using a comparator before, how would I get something like this to work?

**broken link removed**

^The circuit up there seems (key word:seems) like something that might work, but how would I incorporate an LED into this circuit?


Regards

 

[ericgibbs]

Ok, I've been researching this for an hour or so, and it sounds like something that would work - but having no experience whatsoever with using a comparator before, how would I get something like this to work?

^The circuit up there seems (key word:seems) like something that might work, but how would I incorporate an LED into this circuit?


Regards

hi,
Look at this.

 

[alexgeo]

Very new to diagrams, so please bear with me~

**broken link removed**

^I'm guessing this is the 9v power source?

Also, what would I need to change in the circuit to accommodate different voltage outputs from the sensor (let's say I wanted to move the distance)?

 

[ericgibbs]

Very new to diagrams, so please bear with me~

**broken link removed**

^I'm guessing this is the 9v power source?

Also, what would I need to change in the circuit to accommodate different voltage outputs from the sensor (let's say I wanted to move the distance)?

hi,
Yes thats the power supply, I assumed a 9V battery as its a school project.

Make R12 a 5K potentiometer, this will allow you to change the Vref [1v] switching point.

 

[alexgeo]

Wonderful. This will definitely do the trick!

Many thanks,

Alex