Proximity sensors

Thread Starter

joed9988

Joined Dec 18, 2021
20
So im new to the electronics world and i'm learning. this one is making me scratch my head tho and i don't have enough experience using sensors to be sure if the sensor is bad or if it is me.

Amazon Sensor
this is the sensor i bought
So i have a power supply i can adjust the voltage
i wire it
Brown to +
Blue to -
Black is the output

there is a light on the back that lights up when the switch is working it says the switch is 6-36 v but i can only get the light to come on when i give it 8-9v i try 12v and it stops working.
also i was expecting when the sensor would sense somthing the output would be around the same as the input voltage so in this case the only time the light on the back lights up is when i use 8-9v i was expecting to see 8-9 volts on my meter but it doesnt really change it shows around 3 volts even when the sensor is not triggered.
 

michael8

Joined Jan 11, 2015
278
What did you connect the black (output) wire to?
What do you think "PNP NO" the article description means?
Look at how the sensor is connected in the video...
 

MaxHeadRoom

Joined Jul 18, 2013
25,017
As already mentioned, it is open collector output, You need a pull up resistor from output to +ve or some kind of small load, etc.
 

sghioto

Joined Dec 31, 2017
3,067
As already mentioned, it is open collector output,
But the model number indicates a PNP open collector which should switch the supply voltage to the output lead.
Wouldn't be surprised if the wrong item was sent or defective.
joed9988 check the model number on the unit. If it ends in BX it's a NPN type which requires a pullup resistor to measure the output. Should read supply voltage when no motion detected and appx zero volts when motion is detected.
The BY PNP type is shown below.
1640970713186.png
 
Last edited:

Thread Starter

joed9988

Joined Dec 18, 2021
20
But the model number indicates a PNP open collector which should switch the supply voltage to the output lead.
Wouldn't be surprised if the wrong item was sent or defective.
joed9988 check the model number on the unit. If it ends in BX it's a NPN type which requires a pullup resistor to measure the output. Should read supply voltage when no motion detected and appx zero volts when motion is detected.
The BY PNP type is shown below.
View attachment 256517
So more and more i think this thing is defective. so it has a little light on the bottom that is supposed to light up when its working and also has a little sensitive screw on the bottom. now the only time i can get this light to work is when i supply between 8v and 9v. no mater how much i adjust the sensitivity on i have to press my finger up against the sensor for it to work. in my head i should be able to supply it with 12 v and have it sense whatever i put in front of it and adjusting the sensitivity would adjust the distance that it detects objects. now i hooked it up to a small relay i bought and i actually did work to switch the relay but only at 5.5v. relay
 

Thread Starter

joed9988

Joined Dec 18, 2021
20
i get the relay is 5v but why does the sensor now only work at 5.5v it was working at 8-9v without the sensor
 

Thread Starter

joed9988

Joined Dec 18, 2021
20
So any reason you bought the capacitive variety ?
The more common is the inductive sensor for metallic object sense.
well i did have an application for it i dunno if it would work ive only just started to experiment and play around with this stuff but basically the material i was trying to have it sense was not metal.
 

Thread Starter

joed9988

Joined Dec 18, 2021
20
now this is how i got it to work and it would open and close the relay what i dont understand why the sensor only works with 5.5v in this config if i take the relay out and just go + to + - to - and leave the signal wire disconcted the sensor light will turn on and off with 8 to 9v. i thought this sensor could use 6 to 30 v to work so why would it no work if i put 12v to it
 

Thread Starter

joed9988

Joined Dec 18, 2021
20
its a isolated relay so i didnt include the No/Nc/Com side i can here they relay open and close so i know it works
 

Thread Starter

joed9988

Joined Dec 18, 2021
20
Also what component composition are you using to trigger it?
well my understand was that the sensor should trigger from pretty much anything plastic, wood, liquids ect but for the testing purposes ive just be using my hand i also used the table at some point.
 
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