Wireless Remote - 4 Channel Relay? Electricians help please?

Delta3D · 16 Jun 2020 at 18:11

Hi there,

So a little background. I'm doing a little project on my car. I want to make my own valve controller for an S3 8V (2015) so I can have buttons to do the following functions mapped buttons on a wireless remote.

Buttons:
A: Open Valves
B: Close Valves
C: Factory Functionality (Bypass this chip)
D: Nothing (Can't seem to get widely available 3CH Relay?)

The valves function is really simple.
3 Feeds of:
A: Power (Fed from car, so presumably 12v with fluctuations up to 14v)
B: Switch
C: Ground

To open the valves, the switch feed is grounded out, and valves open

To close them, switch feed is not grounded.

What I want to do, is make a combination of buttons to force this to either open, close or OEM functionality.

Question 1:
Would this work?
https://qiachip.com/collections/dc-...remote-controls-kr1204?variant=22446066827312

Question 2:
Would the feed varying between 12-14v affect that chip by burning it out?

Question 3:
How would one ensure there is no moisture inside the box when left attached to the underside of the car. Just glue a plastic pvc type box together around it?

Any help is much appreciated!

Cheers

Diddums · 16 Jun 2020 at 19:53

You should post this in motors so Fox can ask you why you're bothering with a 5 year old Audi.

D D Danneh · 16 Jun 2020 at 22:56

What is the factory functionality? I'm guessing the switch feed (I'd call that the valve controller output) is normally wired into the ground feed (valve controller input), and then the stock controller decides whether to turn the switch on or off depending on your driving?

If that's the case, then yes I think that will work. I can't tell for the rest of the components but those relays are rated for +20% voltage on the coils, so up to 14.4V, and most components are rated similarly. Heck worst case all you've lost is a tenner.

I would wire:

12V DC to terminals +V and 2
0V to terminal GND (simplest "0V" is a chassis connection, guessing you aren't crimping, so just strip the wire, wrap around a bolt, tighten the bolt)
Switch / output to terminal 8
Ground / input to terminals 3 and 9

Then set A, B and C to latching modes, meaning:
A: lets 12VDC through to input, valves open constantly.
B: does nothing, disabling A and C relays, disconnecting input from 12V, valves closed constantly.
C: lets the switch output through to input, letting the stock controller make the decision.

As for IP sealing, in an ideal world you want to get an enclosure, something like this:
https://uk.rs-online.com/mobile/p/general-purpose-enclosures/1533674/
and put a cable-gland in it, something like this:
https://uk.rs-online.com/mobile/p/cable-glands/6694654/
Then route a cable through the gland with at least 4 cores, wire it up and mount it - ideally protected, above something, to avoid rocks flicked up from the road smashing the case, though ABS is pretty tough.

Not sure about sealing your other connections, that'll depend on where the wires are coming from.

This all depends on what the factory functionality is, if you let me know how it's currently wired I can tell you what to tap into.

Adam_151 · 17 Jun 2020 at 00:07

That would work, although it sounds like he needs a switched ground, rather than a switched +ve.

I'd be slighly wary about being able to backfeed the existing controls though and what possible effect that might have.

I'd be tempted to set it up with the two relays as chansgeovers, with the first being an auto/man changeover. and the second being whether manual is on or off.

I.e. You'd drive the output from 2 (common of KC1), the existing controls would be fed into 1 (NC of KC1). Then you'd link 3(NO of KC1) to 8 (Common of KC2), then you'd put ground onto 6 (NO of KC2).

If you wanted factory functionally, you'd turn KC1 off, the position of KC2 doesn't matter, this means that if the unit fails it drops back into factory functionally
If you wanted manual control, you'd turn KC1 on to put it into manual, then you could turn KC2 on to open the valves, or turn it off to close them.

You only actually need two channels, think of it as two bits, and of the four states that gives you, two are the same. (the first to control whether it is factory functionally or manual, and then the second to decide what that manual state is)

D D Danneh · 17 Jun 2020 at 07:25

Good point, could be that the switch feed isn't providing 0V or 12V, more that it's connecting or disconnecting the ground feed from 0V, which would make more sense given the naming.

Perhaps a safer thing to try first would be putting 0V to terminal 2 instead of 12V. If that works, great, if not, it's less likely to damage the valve controller.

Delta3D · 17 Jun 2020 at 17:18

D D Danneh said:
*Snip*

Adam_151 said:
*Snip*

That's perfect, thank you both for your input I really appreciate it. And it's a great help!

I hope this video helps explain what the switch feed would be using. I'm guessing 0V?

if not I can go down to the garage and test with a multimeter to see. I've got a 14v power supply that actuated the motors when I had the below setup and touched the switch terminal to the ground?

POWER Supply
Red Terminal - Valve 12v Terminal
Nothing - Switch Terminal
Black Terminal - Valve Ground Terminal

https://www.youtube.com/watch?v=nOp8vng52PY

Delta3D · 17 Jun 2020 at 17:48

Adam_151 said:
I'd be tempted to set it up with the two relays as chansgeovers, with the first being an auto/man changeover. and the second being whether manual is on or off.

You only actually need two channels, think of it as two bits, and of the four states that gives you, two are the same. (the first to control whether it is factory functionally or manual, and then the second to decide what that manual state is)

Also regarding this point, I had a think about it and agree that this could work well. However my main issue would be determining what state it's in. My main drive to create this is to avoid cold starting with the valves open as the neighbours will not be happy

So just thinking it may be better to have 3 Channels just incase

Cheers

Delta3D · 17 Jun 2020 at 18:43

So have just done a test with the power supply and valves on the exhaust.

Looks like they actually open when the switch touches the ground and then close when the switch leaves the ground.

Have stuck a multimeter on the switch and it’s reading 12.8v on a 13.8v Supply

Adam_151 · 17 Jun 2020 at 18:43

You could switch it around so the default is manual and valves closed and wire the board off the ignition feed so its only powered when the car is on, so that its always in a reset state when you turn it on

Delta3D · 17 Jun 2020 at 19:18

Adam_151 said:
You could switch it around so the default is manual and valves closed and wire the board off the ignition feed so its only powered when the car is on, so that its always in a reset state when you turn it on

I believe the plug that the oem setup plugs into is CANBUS and turns off when the ignition is off anyway so saves sorting that.

I'm assuming for simplistic sake of creating the wiring I can just send the 0v feed back the earth in the factory plug? (Power, Switch, Earth)