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Russell H.
Russell H., Service Tech
Category: Consumer Electronics
Satisfied Customers: 10784
Experience:  8+ years of professional experience
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I have a linear analogue effect sensor, specifically a

Customer Question

hi, i have a linear analogue hall effect sensor, specifically a HONEYWELL SS49E but its has a quiecent voltage of 50% of input i would like it to output 0% when there is no magnetic field and 100% with 100% feild can i use a pull down resistor to drop its output to 0 when there is no magnetic feild detected specifically to detect the position of a brake lever on a motorbike
JA: What's the make/model of your device? How old is it?
Customer: its a new design i just need to detect the position of a lever, with a 0-5V output or 1-4V, any linear voltage output relating to position
JA: How long has this been going on? What troubleshooting have you tried?
Customer: well its a new design
JA: Anything else you want the electronics expert to know before I connect you?
Customer: nope that will be enough in short i need a hall effect sensor to output low voltage when no magnetic feild and full foltage with full feild
Submitted: 8 months ago.
Category: Consumer Electronics
Customer: replied 8 months ago.
will a pull down resistor bring the no field output down below 1v from 2.5v?
Expert:  Russell H. replied 8 months ago.

Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

The pull-down resistor will pull down the 'high' voltage too, as well as the low voltage.

What you want may be, a transistor switch, that will turn Off completely when its input voltage or bias voltage across e.g. emitter-base (for an NPN base-emitter circuit) drops below 0.5 V or so.

Does that sound right?

What input voltage, for both positions of the lever, would the hall effect sensor produce by itself?

We can find something that will work, I am sure... but a pull-down resistor may not work well.

Customer: replied 8 months ago.
Thanks for that, I tested the pull down earlier and it's correct, while it did bringgg the quiescent voltage to 1 or .8 it reduced the high voltage by the same amount so not solving the issue
Expert:  Russell H. replied 8 months ago.


As I said, a transistor used as a switch on the output of the hall effect sensor, may be what you need. Its response to voltage levels would be non-linear, and hopefully act as a 'switch' that would turn Off altogether at a lower voltage level, but remain open, conducting voltage, at a somewhat higher voltage level.

This behavior of a transistor used as a switch is characteristic of proper biasing voltage.

If you tell me these three voltage values in the circuit:

1. the Vcc or + supply voltage

2. the voltage from the hall effect sensor when the lever is in one position (the higher voltage of the two, (2) and (3) here)

3. the voltage from the hall effect sensor when the lever is in the other position (the lower voltage)

I can give you a schematic showing how to get a low voltage from the transistor in one lever state or position, and a high voltage from it in the other position.

Customer: replied 8 months ago.
Thanks ��
the input vcc is 5v
I woukd like an analogue output from say 0.8v to 4.5v or as close to rail to rail as I could get from that hallIs there any analogue linear hall sensor that has a quiescent voltage of 0 rather than vcc/2?Its for anow electric brake lever I want it to output Low voltage when no brake applied and linear output to 5v as brake is applied,I have a design that works with the the magnet sliding over the sensor (image attached) but am looking for a way for it to work with a sensor head on
Expert:  Russell H. replied 8 months ago.

If your hall sensor will be given

+ 5 Vcc

and it will register when 'not sensing'

+ 5 V

and it will register when sensing

+ 2.5 V

then a transistor added to it will take care of the 'output' being

+ 4.75 or so

when not sensing


+ 0.8 V at most

when sensing.

Would that do?

Customer: replied 8 months ago.
Would that be a linear analogue scale as the magnet approaches the sensor head on though or turn it into an on/off arrangement
Customer: replied 8 months ago.
we need the lever to output a variable signal to the controller to operate the regen
Expert:  Russell H. replied 8 months ago.

Yes, a transistor switch would add an effective on/off function.

Customer: replied 8 months ago.
we need it to be Linear analogue from 0 to 100% depending on lever position though not digital 1/0
Expert:  Russell H. replied 8 months ago.

In other words, you want the circuit to go in an even progression from one voltage level to the next, depending on and matching the position of the lever?

As opposed to just switching 'On' and 'Off' - it should represent the position of the lever in the voltage level, right?

Customer: replied 8 months ago.
Yep thats correct, i can do it with a honeywell SS49E but its bipolar and needs the magnet to pass it from north to south etc, i am looking to design a solution which lets me have the magnet approach head on
Customer: replied 8 months ago.
Off can be anything up to around 1V and then progressibly more up till between 4 and 5V
Expert:  Russell H. replied 8 months ago.

For linear response curves, you need solely linear components. A transistor circuit cannot give such linear response, transistors are non-linear components.

I never studied solely-non-linear circuit design... I know the components, I know the responses of those components, but the overall concept of not having active non-linear electronics involved is somewhat beyond me.

I suggest an array of resistors might produce what you need... but I'm not quite certain of even that.

With regrets, I have Opted Out, opening this case to other Experts in this category.