Correct hall effect switch usage

[rbrainard]

Hello all. I had a quick question.
I have a 4510 counter I made that uses a button and Schmitt trigger to count. What I am hoping to do is replace the button and trigger with a OH090U HALL EFFECT switch (has an internal schmitt trigger) but can't seem to get it to work. The counter works with the push button but when I install the hall effect switch it won't count. Is there something I am missing? How much current is required to make the counter acknowledge "high"?(The hall effect switch put out about 10-12mA when I tested it) Any help is greatly appreciated.

I got the idea fro this project from this site:
http://members.shaw.ca/roma/up-down.html

Thanks in advance,
Ryan

 

[rbrainard]

Ok, looking close at the specs of the hall effect switch, it has an average output voltage of 100mA. I suppose that is not enough to power the ic. Does anyone have any idea what type of amplifier I should use and any times on how it would be installed? Again, any help would be greatly appreciated. I am new to the circuit world and I need all the help I can muster.

Thanks in advance,
Ryan

 

[surajbarkale]

Remove the transistor 2N2222 (connected to switch) & directly connect output of hall effect sensor to the point where emitter of that transistor was. The output current of hall effect sensor is not important here. Also make sure that you are operating the Hall effect switch sorrectly by connecting an LED at it's output.

 

[rbrainard]

CORRECTION:
In my second comment I put "100mA." What I meant was 100mV.

Thanks for the reply. I will try the LED test when I get home. As for the output voltage of the sensor, should I worry about the output voltage?

 

[surajbarkale]

100mV won't be sufficient to turn on the transistor. Check the specifications of sensor again. If possible post a datasheet or number.

 

[audioguru2]

Hi Ryan,
The datasheet for your hall-effect sensor shows that it has an open-collector transistor on its output. That transistor does nothing without a collector resistor to the positive supply. Even if you added a collector resistor, your circuit needs a high input like is provided by the pushbutton, but the hall-effect sensor's output will be active-low.
Maybe you could re-arrange the pushbutton transistor to be an inverter and to provide a collector resistor to the hall-effect sensor.

 

[rbrainard]

Good news, I got it to work over the weekend. What I didn't notice is that the hall effect switch pulls down and not up as I had belived. So, I replaced the push button with the hall effect switch and changes the 2N2222 NPN transistor to a Radio Shack 3906 PNP and it worked. Hurray!! Thanks for your help Suraj.

Ryan

 

[rbrainard]

Thanks AudioGuru, looks like we posted about a minute apart. The terminology is all new to me. When I read the data sheet, I didn't know what "Pull-Down" meant exactlly until I hooked up some LEDs and figured out that the hall effect switch simply allows the circut to ground out. Slowly, I learn what the heck I am doing. Thanks for the help and patience.

 

[audioguru2]

Hi Ryan,
I'm glad you got it to work.
You are clever to use a PNP transistor so that it doesn't need an additional inverter. ;D

 

[ante1]

Here is some facts about Hall effect switches :

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