Hall effect sensor issues

Thread Starter

boblug

Joined Feb 21, 2021
8
Im trying to make a magnetic trigger and using a 3144 sensor.
The strange thing is supplying 5v as input only shows .5-.6v on its output leg so is not enough to trigger an led.
Is this the wrong type I am using, I have watched several youtubes and they all show 2.5V plus on the output pin.
 

MaxHeadRoom

Joined Jul 18, 2013
23,104
They look similar to the Honeywell SS400 series I use, the output appears the same, i.e. open collector.
You need a pull up resistor or load to register an output.
Max.
 

Thread Starter

boblug

Joined Feb 21, 2021
8
Hi, Im back again. So I made my test circuit, very simple and exactly based on the above sketch.
On the bench it works great and the output pin is pulled high, just as I need.
So I then made a small proto board version and first my green LED died (still dont know why) but the biggest issue is now when activated it only reports 1.8ish volts on the output side, its as if the LED is draining all voltage. I retested this by manually putting an LED on the board and it does the same, without LED is fine.
The picture is just to show you the application excuse the soldering but it is made exactly as the diagram above. Although you cant see it the resistor connects under the board to +V.
Purple=5V in, Yellow=ground, Orange=output (these are temp just for pic)
Any thoughts on my mistake here?
 

Attachments

sghioto

Joined Dec 31, 2017
2,363
the biggest issue is now when activated it only reports 1.8ish volts on the output side,
When activated which means when the magnet is near the output should be near zero volts.
If it worked on the bench but not on the proto board then the board is the problem.
There's no way to tell from the photo what may be wrong. Are you sure the sensor is installed correctly?
Connect a 10K resistor across the LED and the output will read 5 volts when OFF, magnet not near.
If you don't need the LED just use a 10K resistor from the output of the sensor to 5 volts.
1615244812820.png
 
Last edited:

Thread Starter

boblug

Joined Feb 21, 2021
8
Hi sghioto, thanks for feedback. I used your example from before.
This is very odd, I actually used a 1k instead of 470ohms and when no magnet there is zero V on output. When applying magnet this gives +5V which is what I wanted actually.
Sorry for picture it was just to show my device not wiring.
Anyhow, I will go back and try your idea of 10k.
I am using the front or chamfered face of the sensor for activating.
 

Thread Starter

boblug

Joined Feb 21, 2021
8
ooh, no I was measuring from +v to output. Either way output goes high. Ill try your suggestion later this evening. Thx for help.
 

Reloadron

Joined Jan 15, 2015
5,934
Keep something in mind. The maximum current that sensor can sink is 25 mA when it goes low (active). If you are directly driving a LED make sure your circuit allows adequate current for the LED and make sure your circuit will allow whatever the LED current is.

Ron
 

Thread Starter

boblug

Joined Feb 21, 2021
8
Thanks, measuring across -v and output drops to near zero v. I will change my software to activate based on going low. Thanks all for help.
 
Top