How can I trigger a device using a momentary tact switch already on another device?

[BrandonB]

How can I trigger a device using a momentary tact switch already on another device?

I have a smart device that has a N/O momentary tact switch on its PCB.
I would like to use this switch to remotely trigger a remote bell.
The remote bell can be triggered using a momentary switch to connected to its trigger inputs.

When I soldered wires to the smart device tact switch and then connected those wires to the trigger inputs of the remote bell it is triggered as soon as both wires are connected... without the tact switch being pressed and closing the circuit.
The remote bell cannot be triggered again until a wire is disconnected and then reconnected to its trigger inputs.
It is acting as though the tact switch is closed even though it has not been depressed.

When I use my DMM across the SMD legs of the tact switch I get the following:
(The readings were obtained with the smart device disassembled and powered off. There is a button cell onboard to retain settings.)

continuity
open = 2.428
closed (pressed) = 0.002

resistance
open = 5.66 kOhm
closed (pressed) = 0.0 Ohm

smart device tact switch

I have looked into simple mosfet and relay circuits to act as the middle man but I'm not really sure what would be the most reliable.
I have tested the smart device with a relay and it DOES NOT trigger the relay until the tact switch is pressed.
I don't think it would be a good idea to send any additional voltage through the smart device tact switch as I do not want to interfere with its original use or fry something in the smart device.
Is there a diode or something that I could add to the wires I connected to the smart device tact switch to prevent the remote doorbell from being triggered until the tact switch has been pressed?

Other details
The smart device has its own power supply (24VAC).
The remote bell has its own power supply (6VDC).
The devices are about 50 feet apart.

I did some further testing with a 12VDC power supply, a 12VDC mini SPST relay, and the smart device... I don't have the remote bell with me right now so I cannot fully test what I had been working on or what you recommend right now.
When I connect the smart device tact switch to the relay it does not trigger the relay until I press the tact switch.
After I release the smart device tact switch, the relay does not open.

Here is a diagram showing how I have it set up:

What route do you recommend I take?

Is there a way I can add a resistor and a capacitor (or something) that would draw down any voltage that is holding the relay closed?

Thank you all for your help!

 

[Les Jones]

I think that I misunderstud your original problem. I missed the point that the problem ocurred when the smart device was powered down.
This was MY understanding of your problem. Your smart device is a wireless door intercom and that you are trying to use a button on the INTERNAL unit to trigger a bell in some other part of the house. All along I have been wondering why you want to use a button (Which has a function unknown to me.) to trigger a bell. I now think that the device is the push button on the outside of the house. (Adding a backup bell to this does make sense.)
If my new understanding is correct then I think adding a diode inside the smart device will solve the problem. The non ground side of the button will probebly be connected to a pull up resistor to + 3.4 volts and the input of a logic IC or microcontroller. Internal to this IC there are probably two protection diodes (One to ground and the other to VCC.) When the unit is powered down the wire from the P connection on the bell (At about + 3 volts.) will be attempting to power all the logic circuits in the smart device via the protection diode to VCC in the IC. It will not be capable of doing so and will be pulled down to a low enough level to trigger the remote bell.
The solution would be to cut the track from the push button to where it connects to in the smart device. You would then need to bridge this break with a diode so that the button could pull it to ground but the positve voltage comming in from the bell could not connect to the smart device logic. (The cathode of the diode to the top of the push button switch.) adding the diode would mean that the push button only pulled the logic input down to about +0.6 volts. This would still probably still be seen as a logic low so is should still trigger the logic. I suggest usink a schottky diode as these have a lower forward voltage drop than a normal silican diode.

Les.

 

[BrandonB]

I think that I misunderstud your original problem. I missed the point that the problem ocurred when the smart device was powered down.
This was MY understanding of your problem. Your smart device is a wireless door intercom and that you are trying to use a button on the INTERNAL unit to trigger a bell in some other part of the house. All along I have been wondering why you want to use a button (Which has a function unknown to me.) to trigger a bell. I now think that the device is the push button on the outside of the house. (Adding a backup bell to this does make sense.)
If my new understanding is correct then I think adding a diode inside the smart device will solve the problem. The non ground side of the button will probebly be connected to a pull up resistor to + 3.4 volts and the input of a logic IC or microcontroller. Internal to this IC there are probably two protection diodes (One to ground and the other to VCC.) When the unit is powered down the wire from the P connection on the bell (At about + 3 volts.) will be attempting to power all the logic circuits in the smart device via the protection diode to VCC in the IC. It will not be capable of doing so and will be pulled down to a low enough level to trigger the remote bell.
The solution would be to cut the track from the push button to where it connects to in the smart device. You would then need to bridge this break with a diode so that the button could pull it to ground but the positve voltage comming in from the bell could not connect to the smart device logic. (The cathode of the diode to the top of the push button switch.) adding the diode would mean that the push button only pulled the logic input down to about +0.6 volts. This would still probably still be seen as a logic low so is should still trigger the logic. I suggest usink a schottky diode as these have a lower forward voltage drop than a normal silican diode.

Les.

Yes, I think we were all a little confused about everything.
I honestly didn't know that the problem (making the remote bell (iChime Doorbell) chime and not chime again) only occurred when the power wasn't connected to the smart device (Reolink Video Doorbell).
I didn't figure this out until later on because I was trying to be careful when probing around and working inside the smart device (Reolink Video Doorbell)... I didn't want to fry it.

I think you have the general idea now...
The smart device (Reolink Video Doorbell)...
- is a replacement doorbell button on the outside of the house
- has an internal tact switch...
- that makes the it record video
- that makes it chime a wireless bell
The remote bell (iChime Doorbell)...
- is a replacement doorbell inside the house
- is located in an area where the wireless bell cannot be heard

Is there any way to achieve what you are recommending with the Schottky diode without cutting a trace for the tact switch on the smart device (Reolink Video Doorbell)?
I don't want to prevent it from working properly after this (essentially permanent) modification.
I would prefer to have something inline with the two wires that I soldered to the tact switch inside the smart device (Reolink Video Doorbell) and then ran outside of the unit which then connect to the trigger inputs T and P of the remote bell (iChime Doorbell).

Thank you for your help.