RC Motor on-off setup with KeyFob Remote

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
I am setting up a radio control model boat with twin motors. The battery is a 3s Lipo. The speed controllers (ESC) for the motors were a kit project. The KeyFob remote I am using was purchased off of Amazon and is this one. I am not using resistors for the LED's. In place of resistors I am using CL2N3's for 20ma to the LED's.

I have two ways to turn on power to the motors.
The first is to move the motor switch to a position which provides direct power to the Positive Block/ESC's. This would light up LED B as an indicator. The KeyFob is not used in this position. I call this DIRECT.
The second is to move the motor switch to the other position which provides power to the Remote KeyFob device. This allows me to turn off power to the motors remotely of course. This would light up LED A as an indicator. I call this REMOTE.

Both DIRECT and REMOTE connect at the Postive Block which is a junction providing power to the ESC's.

My problem is this. When I set the Motor Switch to DIRECT, the ESC's work fine and LED B lights up. When I set the Motor Switch to REMOTE, LED A lights up, then I press the button on the KeyFob remote and the ESC's get power. The problem is that when the KeyFob is pressed, LED B turns on. So LED B is getting power to turn on.

How do I stop LED B from turning on?



BMS.jpg
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Maybe pictures will help?

When I flip the center toggle switch to use the KeyFOB device, the Remote LED goes on. This gives power to the black box under the KeyFob. At this point there is no power going to the two speed controllers. The terminal block (red) to the right has the output of the switch (Direct), output of the KeyFob device, and the two speed controllers connected to it.

IMG_3174.jpeg


Now A was pressed on the KeyFob, turning on the KeyFob device and now the speed controllers have power. And since the Direct LED is also tied to the terminal block, that LED goes on, which I do not want it to. The way I wired this up I did not catch that power would go to the LED. That LED is supposed to only go on when the toggle switch is set to Direct..

IMG_3175.jpeg

The motors will draw 1-3 amps, more likely around 2 amps I am guessing. They draw 0.6 amps connected directly to a battery. So around 2 amps will be at the terminal block. Not knowing enough about electronics a diode I guess will fix the LED problem? But would have to use and LED that handles that current? That is why I am here seeking help from experts.
 

crutschow

Joined Mar 14, 2008
34,452
How do I stop LED B from turning on?
Below is one approach:

Both LEDs share a common current-limiting resistor to ground

When the Motor Switch goes On, voltage is applied to both LEDs in parallel, but the added forward drop of D1 prevents LED A from turning On.

When the Motor Switch is Off and the Remote Relay is energized, only LED A goes On.

Edit: Due to D1, the current through LED A will be a little less than through LED B.
That will likely only make a small visible difference in brightness, but if that's not desirable, then adding a small resistor across (in parallel with) LED B, should even the currents.
Start with about 1kΩ and experiment from there to get equal brightness.


1707765822669.png
 
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Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
The Motor Switch is an on-off-on switch. One on being direct power to the motors (not using the remote device) and the second on providing power to the motors thru the remote device. The reason using an on-off-on switch is that while a battery is in the boat, I don't want a drain from the battery while it is not needed. With the switch off as you say, the remote device will still draw power from the battery, albeit that power draw is low as it needs some draw in its off state so it is in standy mode to detect a signal from the KeyFob button.
 

crutschow

Joined Mar 14, 2008
34,452
The Motor Switch is an on-off-on switch.
Then here's the connections for that:
Looks like I originally misunderstood how you wanted the LEDs to work, so the circuit is changed to reflect that.

Now LED B lights only when the switch is in the Direct position, and LED A lights only when the switch is in the Remote position, per my revised understanding.
Using both throws of the remote module's relay contacts, allows complete separation of the the two LEDs power.
1707843885305.png
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
That is very close to my original hand drawn drawing. The problem with your drawing is the item you have labeled as Remote Power is incorporated into what you labeled as Remote Relay. They are not separate items. That is the device I call KeyFob Remote in my hand drawing.

With my limited knowledge I was thinking this. Could I put a diode in the line that goes from the positive terminal block to the Motor switch direct side before LED B? But it would have to be a diode that would allow enough current for the motor which would be 2-3 amps.
 

crutschow

Joined Mar 14, 2008
34,452
The problem with your drawing is the item you have labeled as Remote Power is incorporated into what you labeled as Remote Relay. They are not separate items.
I understand that.
I didn't mean to imply they were separate items, but the receiver does have separate connections.

The node labeled Remote Power is the connection to power the remote receiver.

The remote relay is, of course, part of the receiver with its own separate, isolated SPDT contact connections.

Do you still see a problem with my circuit?
 
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Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Does this help? This is the entire board. The receiver for the Keyfob is integrated on the board. The coiled wire is the antennae. LED A from your diagram would have to be tapped in a contact on this board? The ESC Output I currently have going to the Positive Terminal block which in turn connects to the ESC's.

IMG_3191.jpeg
 

crutschow

Joined Mar 14, 2008
34,452
This is the entire board.
Yes, and below is the bottom of that board.
"C" is by the relay outputs (left on your board).

So per my diagram in Post #5 (see your revised picture at bottom) --
NC (bottom left connection on your picture) is connected to the switch Direct output.
COM (middle left connection on your picture) goes to the ESC.
NO (top left connection on you picture) goes to the switch Remote output.
Remote Power goes to V+ (A).

It's not totally clear to me if you need to solder any of those bridges to get the desired operation.
You may have to use an ohmmeter to determine that.
You don't want any connections from the power input plus and minus terminal to the relay COM or NO terminals.
The only connection is from the V+ terminal to the NO terminal.

That all make sense?
1707868588407.png
1707870873755.png
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Yup thats the bottom of it. A and B need to be soldered. C needs to be unsoldered. That will put it in a latch mode. Push the remote button and it will latch power on.

It's late now. I'll have to check what you say on Wednesday. Thank you for your help.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
I got these 2 months ago. As they arrived they were setup so when you pressed the Keyfob, the output was only momentary. Not what I wanted. I wanted, press the button, the output stayed on. So according to these instructions, I soldered A and B and that gave me what I wanted, the outer two gave me ground and input V when the device was activated. I was not concerned about the center connection. Is there something I should change?

This is the device.... Remote control switch . Which you already know.

Screen Shot 2024-02-14 at 12.17.48 PM.png
 

crutschow

Joined Mar 14, 2008
34,452
You do not what the connection for a live output from the power input, so A and B should not be bridged with solder.
You want it connected exactly as I posted.

Is my posting not clear?
You seem to have difficulty understanding that.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Let me start over and let's get the bridge joints right, OK?
We can get back to the LED issue after we have the bridge joints straight. I'm working with the 'B' device as a test.

For the bridge connections this is what happens....

A,B,C all unsoldered - No output on 1,2,3 and no ground connection
C soldered - No output on 1,2,3 and no ground connection
B soldered - No output on 1,2, 3 is a ground connection
Did not join B and C as they both would connect to Pin 3 and to a relay pin

Only A soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - No connection to ground, no reading

A+B soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - Verified ground

A+C soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - On 0v | Off 12v

IMG_3195 copy.jpeg

Bridge A - Provides power to Pin 1 and Pin 2
Bridge B - Provides ground to Pin 3, without Bridge C soldered
Bridge C - Provides opposite power to Pin 1, without Bridge B soldered

So to me it looks like I can use it with A+B or A+C joined.

As long as all the grounds are joined elsewhere I can use A+C joined and take advantage of Pin 3 being the opposite of Pin 1.

And Pin 2 will always have power whether the device is on or off, a passthrough.

I had to do this just so I have in my mind the different results of those three bridges being joined or not.

Does this help at all?
 
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crutschow

Joined Mar 14, 2008
34,452
Does this help at all?
Yes.
From this--
Bridge A - Provides power to Pin 1 and Pin 2
Bridge B - Provides ground to Pin 3, without Bridge C soldered
Bridge C - Provides opposite power to Pin 1, without Bridge B soldered
What is "opposite power to Pin 1"?

Still confused since It looks like:
Bridge A connects V+ to COM
Bridge B connects GND to NC
Bridge C connects NC terminal to the NC relay pin.
So to me it looks like I can use it with A+B or A+C joined.
From what I see only Bridge C should be connected.
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Ken_NJ said:
Bridge A - Provides power to Pin 1 and Pin 2
Bridge B - Provides ground to Pin 3, without Bridge C soldered
Bridge C - Provides opposite power to Pin 1, without Bridge B soldered
What is "opposite power to Pin 1"?
With A+C soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - On 0v | Off 12v
When the device is powered off, Pin 3 measured 12v and Pin 1 was 0
When the device is powered on, Pin 1 measured 12v and Pin 3 was 0



Still confused since It looks like:
Bridge A connects V+ to COM
Bridge B connects GND to NC
Bridge C connects NC terminal to the NC relay pin.
This is a made in China device. The instructions are awful and don't explain much to me. Me, I would ignore the artwork on the board as depending on which bridges are soldered you get different results on the output. I ran through this test twice to verify the results before I posted them here.


Ken_NJ said:
So to me it looks like I can use it with A+B or A+C joined.
From what I see only Bridge C should be connected.
When I only had Bridge C soldered there was no output on any pin. And there was no ground connection on any pin.
C soldered - No output on 1,2,3 and no ground connection
So what is the purpose of Bridge C?
- Bridge C made Pin 3 work as on-off with the remote.
- Bridge B made Pin 3 work as a ground.
- So either Bridge C should be soldered or Bridge B should be soldered. Not both at the same time.
They both determine what Pin 3 does. But Bridge A also has to be soldered in order for there to be any output.



If you look at post 12, the picture provided from the Amazon page, it does says to solder bridge A and B with the result being the Pins 1 and 3 will activate the light in the picture. So with my testing, it turned out that Pin 3 is Ground and Pin 1 was on & off with the remote.
A+B soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - Verified ground

If no bridges are soldered, this happens...
A,B,C all unsoldered - No output on 1,2,3 and no ground connection

If you solder bridge A, this happens...
Only A soldered -
> Pin 1 - On 12v | Off 0v
> Pin 2 - On 12v | Off 12v
> Pin 3 - No connection to ground, no reading
If you do not solder bridge A then you do not get output on Pins 1&2

So bridge A makes Pins 1&2 work (Pin 1 goes on & off with the remote, Pin 2 is always on no matter what the remote does)
Bridge B makes Pin 3 a ground (but do not solder bridge C)
Bridge C makes Pin 3 on & off with the remote (but do not solder bridge B)

Does all this sound logical?
 

crutschow

Joined Mar 14, 2008
34,452
When I only had Bridge C soldered there was no output on any pin. And there was no ground connection on any pin.
That's what we want.
The output function is a SPDT relay contact (similar to a switch) with only external connections.
So either Bridge C should be soldered or Bridge B should be soldered. Not both at the same time.
They both determine what Pin 3 does. But Bridge A also has to be soldered in order for there to be any output.
Agreed.
Bridge C should be the only bridge soldered, as I stated in my previous post.
We don't want any output or internal connections to ground or 12V, just the contact function of the relay for the external connections I show.

Does that not make sense to you?
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
Does that not make sense to you?
Sorry to say that it does not. And I want to know why. I am trying to understand.

Am I explaining this right from what you are telling me?
With only bridge C soldered, there will be no output on the three output terminals, those I have labeled as Pins 1,2,3. So those terminals are useless. We don't want A soldered so the relay does not get internal power. Only connect 12v and ground at the two input terminals.

Somewhere on the PCB we are going to tap in 12v to the relay. And going to tap out a line going to the LED. Then somewhere we are going to tap out from the relay a line going to power up the speed controllers.
And the end result of this is all to have the Remote LED come on and the Direct LED not come on from the on-off-on switch?


1707843885305.png
 

crutschow

Joined Mar 14, 2008
34,452
With only bridge C soldered, there will be no output on the three output terminals, those I have labeled as Pins 1,2,3. So those terminals are useless.
Useless?
I do not understand why you think those relay contact terminals are "useless".
Are the contact terminals on a mechanical switch also useless?

The connections here are made to the relay contacts, the same as if we were connecting them to a switch contact.
The only difference is a voltage to the relay coil changes the contact position, instead of a manual switch toggle.
The sole purpose of these contacts is to make a switchable connection between two of the terminals, not to generate an "output".

My diagram below (updated with the contact designations) clearly shows how the relay contact connections are to be made
There is no internal output, as such.

You seem to be hung-up on the idea that you need some internal output from the relay.

The source of the confusion here seems to be that you do not understand how the relay works in your module.
If this is still so, then please read up on relays, as I am at a loss as to how to further explain. :confused:+

Incidentally, your picture in Post #14 has the NO and NC designations reversed.

1708019471306.png
 

Thread Starter

Ken_NJ

Joined Feb 22, 2021
43
As we chat, I'm understanding more. Thinking useless was wrong as I see the what you are doing in the new drawing, and follow and compare to the PCB.

What I see is this...
With bridge C soldered, Direct from the switch is directly connected to the NC terminal which in turn provides voltage to COM, then the ESC's. If I were to forget and leave the KeyFob home, I would still have power through the Direct path to run the boat. And LED Rled would activate indicating the setting of the switch.

If I did not forget the KeyFob. Toggle the switch to Remote. Press the KeyFob button to tun on the device. NO would close sending power through COM to power the ESC's. As well, LED Rled1 would activate.

And power would still be applied to the inputs as that would power the receiver.

Did I get that right?
 
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