IR Break Beam output voltage lower than 5V

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niclas_adafruit
 
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IR Break Beam output voltage lower than 5V

Post by niclas_adafruit »

Now I've spent my whole sunday trying to figuring out how to get an 5v output signal. I tried with different resistors also with the suggested 10K. I also tried connect it like the PDF https://cdn-shop.adafruit.com/product-f ... /C2917.pdf

However the voltage always drops at the output signal and I have to use a resistor because I haven't got a pull up resistor...

I know how to connect it to a Raspberry Pie, but I want a stand alone electric circuit.

What I want is the signal (yellow wire or white) should produce 5v when beam is crossed (OK also if 5V to 0V), I've connected the output signal to an optocoupler (5v to 24) and I don't want to use a relay because of the speed.
I'm powering the circuit with 5V and I'm pretty sure that I got ground and 5V right on the transmitter/reciever.

I'm not an electrician, please help me!

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Re: IR Break Beam output voltage lower than 5V

Post by adafruit_support_bill »

Please post some photos showing how you have everything connected.

With no load, and a pullup resistor to 5v. It will pull the output to 5v when the beam is broken.

If you have a load on the output, that may pull the output voltage lower - depending on the impedance of your load.

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niclas_adafruit
 
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Re: IR Break Beam output voltage lower than 5V

Post by niclas_adafruit »

It's easier to explain because the protoype looks like a mess and I wasn't planing to expose this to the world, then I might have to change nickname :)

I hope my I explanation will do..

I have a 24V to 5V DC-DC converter and "power in" is 24V (22.8V)

5V -> Reciever (red cable)
GND -> Reciever (black cable)
5V -> Transmitter (red cable)
GND -> Transmitter (black cable)
5V -> 10K ohm resistor (tested with different resistance) -> Reciever signal cable (yellow or white) -> Optocoupler (IN+)
GND -> Optocoupler (IN-)

24V -> Optocouppler (OUT VCC)
24V GND -> Optocouppler (OUT GND)
24V SIGNAL -> Optocouppler (OUT1) is not connected, but I can measure

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niclas_adafruit
 
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Re: IR Break Beam output voltage lower than 5V

Post by niclas_adafruit »

I've measured so I have 5V on my DC-DC converter

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Re: IR Break Beam output voltage lower than 5V

Post by adafruit_support_bill »

We don't know the specs of your opto-coupler. But I would expect that to work.

If the optocoupler load is pulling the break-beam signal too low, you can try using a stronger (i.e. lower value) pullup resistor on the break-beam.

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niclas_adafruit
 
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Re: IR Break Beam output voltage lower than 5V

Post by niclas_adafruit »

You are right, it's my chinese optocoupler that messes things up.
If I disconnect the optocoupler I get 5V.
If I change the resistor to 100 ohm I get 4.2V, with 10K ohm I get 1.2V.

What I want is to change the signal from 5V to 24V in a convenient way and this is the type I bought:
https://www.alibaba.com/product-detail/ ... 19422.html

Any suggestions?

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Re: IR Break Beam output voltage lower than 5V

Post by adafruit_support_bill »

That one is designed to take 24v inputs and convert them to 5v outputs. Just the opposite of what you are looking for.

It looks like they have 5v->24v models also. But they don't provide any detail at all in the specs regarding input impedance or output drive capability. What do you plan on driving with the 24v signal?

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Re: IR Break Beam output voltage lower than 5V

Post by niclas_adafruit »

Thanks for your reply!
I actually have a 5V -> 24V optocoupler, the link was just an example.
The output (24V) from the optocoupler would be connected to an input on a PLC probably

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Re: IR Break Beam output voltage lower than 5V

Post by adafruit_support_bill »

A PLC input should have a relatively high impedance, so it should be easy enough to drive. Have you measured the output of your optocoupler when driven by the break-beam sensor?

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