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Replace mechanical switch with electrical switch or replay Answered


I have a remote controller for a portable heater, and working on a small project to be able to control the fan on/off from an arduino with Bluetooh HM-10 module. I thought a solenoid might work by mounting on top of the remote but it doesnt have enough force, I want to remove/desolder the mechanical button and figure out a way to control it without the switch but kind dont really know what circuit I should use, kind of just learning how to use arduino.

Images of remote and button traces below.

Any idea how I could wire this up to arduino via some switch/relay circuit? Any circuit design / schematic would be helpful

(See pics attached)


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Jack A Lopez
Jack A Lopez

2 years ago

Did you happen to notice that all those little push button momentary switches are wired together on one side?

I am kind of guessing the node where they are all tied together is possibly the same node as the negative side of the battery; i.e. the lowest voltage in this circuit; often called the circuit's "ground" node.

Another likely possibility is that node is the high side of the supply; i.e. the side connected to the positive side of the battery, or the most highest positive, in the case that the battery is a series stack of cells (.e.g. 2x AA, or 4x AA cells).

Actually, now I am thinking it might, more likely, be the high side, since all the plus symbols (+) on those red LEDs look like they are connected to the same node.

Kind of dumb to speculate about, since you have the picture of the whole circuit board, or the board itself, and you could just look at it, and tell us which it is.

Or course it would have been easier if you just told us this to start with, but it may be the case you truly do not know what you're looking at, and thus you have a kind of blindness in this respect.

So, for the sake of clarity, I will make some edits to your pictures, for to point out the node I'm talking/writing about.

Like I wrote before, I am wondering if this node is connected to the battery. Also wondering which side of the battery: (+) or (-)?

Also I am somewhat curious about what size the battery is. Is it 2 AA (or AAA) cells in series? Or 3 cells? Or 1?

Also is that 14 pin IC, one that we recognise, like from the number printed on it?

I mean there are probably clues all over this board, yet you expect the people reading this forum can somehow see the whole thing via some kind of clairvoyance, just by looking at one zoomed-in little corner of it.

Anyway, I made some edits to your pictures, and I drew a hand-drawn circuit diagram explaining the usual trick for connecting a transistor in parallel with a (normally open) push button. These pictures are attached.


2 years ago

It would help to know more about the circuit itself.
These tiny switches are not meant for doing any real switching, more for signal use.
Means if the circuit would run on (ideally) 5V then you could just add a signal from the Arduino directly to the corresponding pin of your existing switch.
Of course this only works if the ground of the circuit and Arduino is shared.
A safer approach would be to use the Arduino signal to turn on a transistor.
This transistor can then either directly "switch" the thing on or switch a relay on to bridge the contact of your existing switch.
If you look in the Arduino Playground you will find a lot of examples on how a transistor can be used to switch things.
Just copy the examples and follow the circuits.
And instead of a "load" or light you have the existing switch.