Hey Guys,

I have a weird question about SmartHome door Sensors.

I purchased one just to look at it and I am confused.
There is the main control board and shell and then the magnet and shell.
With home alarms reed switchs are used the the magnet opens or closes the switch.

I was expecting the same setup with the smarthome door sensors but cant see any reed switch.
The magnet is a magnet and is in shell.
The control board on has components on one side and there is no reed switch located on the pcb.

My confusion is how then does the magnet work on the pcb?
With no visible switch what does the magnet trigger?

Can a chip be affected by the magnet?
On the side of pcb is a little chip that has 3 pins.
It has a code on it that is 2373S 2241.

I can try to take a picture of the pcb but board is so small dont think my phone will take a good picture.

Thanks
Fred

 

Probably a Hall Effect Switch.

 

There are proximity switches that either require ferrous metal, or some require a magnet.

 

VCS2373S SOT-23 Hall Sensor

 

Honeywell have their SS400-SS500 series, Bipolar, Unipolar, latching etc.

 

Hey ElectricSpidey, MaxHeadRoom & sghioto,

Thanks for the fast reply to my query.
I am familiar with Home and Business alarms as am licensed.
That was why I wanted to see how the smarthome sensors worked.
Such as Tuya or others.

But could not find any switch, microswitch or reed switch on the pcb.
Only thing close to the magnet is the one chip.
Nothing on other underside of pcb.

I have attached picture of pcb.

Thanks
Fred

 

" Only thing close to the magnet is the one chip. "

Is that chip marked H1?

I see a number "2241" is that correct?

 

Hello, Yes that is the chip on board at H1.
When I read with jewelers glass it said 2373S 2241

Thanks
Fred

 

H1 as in H of Hall Effect Sensor
Part number 2373S as noted in post #4
Part was produced 41st week of 2022
Pin 1 upper left, connected to thicker trace to C1 (maybe), looks like VDD (power)
Pin 3 right side, connected to plane, most likely GND
That leaves Pin 2, lower left, connected to via, as output going back to controller.

 

Hello,

Ok Thanks for all the help and info, I really appreciate it.

The sensors I have used before all had glass reed switches and I have never seen a Hall Sensor Before.
I will have to read up on them as it seems very interesting to me.

Thanks again for all the help and info.
Fred

 

https://www.state-elec.com/honeywell/pdf/Speed Sensors SS400.pdf

Also Hall sensors have been used on industrial (CNC) equipment for some decades in a limit switch capacity.
Some require a magnet, others respond to ferrous metal.

 

https://www.state-elec.com/honeywell/pdf/Speed Sensors SS400.pdf

Also Hall sensors have been used on industrial (CNC) equipment for some decades in a limit switch capacity.
Some require a magnet, others respond to ferrous metal.

Hey,

Thanks for the more info I appreciate it.

I just thought of one more question.

What is the advantage to using a Hall Sensor over using a magnetic reed switch or wired magnetic contact?

To me it would seem more wasteful as if snsor fails you need to replace whole unit.
Where if a wired switch fails you just replace the switch.

Thanks
Fred

 

With the SS switch, there is no contacts to become worn-burnt etc.
i.e. no moving parts.
Also the difference in cost now is minimal.

 

Certainly there are "Hall Effect" sensors, and there are other sensors that also detect magnetic fields by means that I am not aware of. This includes resistors that change value in response to magnetic flux.

 

The three common types of proximity in use today are detection by magnetism, Ferrous metal, and non-ferrous type, (capacitive).
Almost all use the Hall effect method.

 

Hey,

Thanks for the additional info, i appreciate it.

I still think old way would be better with reed switch.
You could not mount a smart sensor on overhead garage door as the gap would be to great.
With old way Sensor could be on wall while contact could be various sizes to use on overhead door.

But you all gave me the info I asked for so thanks you all very much.
Think I will grab a few other sensors from DSC and Ademco and see if they still use reed switches.

Have a great summer.
Fred

 

I don't understand your garage door example of why you think a Hall sensor can't do everything that a reed switch can do(?).
A Hall sensor can be just as sensitive to magnetic fields as a reed switch.

 

I don't understand your garage door example of why you think a Hall sensor can't do everything that a reed switch can do(?).
A Hall sensor can be just as sensitive to magnetic fields as a reed switch.

For starters, a hall sensor must have a power source, while a reed switch does not. The hall sensor does not change between open and closed, but rather between two voltage states. In addition, the reed switch has only two conditions, either open or closed. And the reed switch is not bothered by transient spikes that will destroy a hall device.

 

There are two types of Hall sensors, two wire & three wire, the three wire versions are intended to switch a load, The two wire are intended for higher impendence sensing, IOW the pair carry the supply as well as indicate the status of the device.
e.g. input into a PLC or Microchip for instance.

 

To me it would seem more wasteful as if sensor fails you need to replace whole unit.
Where if a wired switch fails you just replace the switch.

You are forgetting this is a wireless unit. Whether the module uses an internal reed switch or a hall effect for the sensor and it fails you will still need to replace the unit unless one is skilled at component level repair.