Need help with controlling a door circuit

Thread Starter

banklooker

Joined Mar 3, 2017
11
Hey guys!

I've started gaining more interest in electronics and circuits and I am stuck with a project.

I live in an apartment on the first floor. When somebody comes over and rings the bell I have to walk to the door of my apartment and press a button which opens the front door of the complex for a few seconds. I want to automate this by wiring an rf controlled arduino nano so I can wirelessly press the button.

The system that's in place now is a Siedle BTS 850-02 and I can remove the casing very easily. The circuit looks like this: Front | Back
Now I know that connecting the contacts below a button will open the door - that works perfectly.

As I said I got stuck on powering the arduino. The Ta and Tb Pin have 27.5v DC connected to them but if I use a DC DC step down circuit, the phone is no longer able to talk to the BUS system. My question is if there is any way I could connect the arduino to the phone circuit in order to power it without batterys.

Can you guys help me out with this or maybe give me a few tips on what I should do or look out for?

Thanks a lot!

IMG_0267.JPG IMG_0272.JPG
 

AlbertHall

Joined Jun 4, 2014
8,336
An arduino needs quite a lot of current to operate.
There are radio remote controls available which will draw much less current and so can sensibly be run from batteries. Also, the hard part is making a nice small tidy remote control and buying this ready made is definitely advised.
This gives you a neat remote and a receiver with a relay output. The contact of the relay could be connected across the button to operate the door.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Hi!

Thank you for your reply!
That is what I also thought of, however I did not find anything that operates on batteries. What you sent me also needs a 12V DC input...

Best
 

AlbertHall

Joined Jun 4, 2014
8,336
I believe a 23A battery (12V), the same as is used in the transmitter, would also work the receiver.
 

AlbertHall

Joined Jun 4, 2014
8,336
No, I can't be certain as there is no information on how much current the receiver uses. The relay will need quite a bit of current but it is only operated for that brief time when opening the door so that part will be OK. Given the price and ease of use I think it would be worth the experiment.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Alright, that's true. I will try that solution and hopes the battery does not drain too quickly - thanks!
 

Kjeldgaard

Joined Apr 7, 2016
378
Battery Operation of remote control receivers are usually a bad idea, and together with a 23A battery it can be a really bad business.

The remote receivers I've seen data has had an idle power consumption of between 1 mA and 5 mA.
A 23A battery has a capacity from 40 mAH and some types up to 60 mAH.
If we make e calculation on a receivers 2 mA consumption and a battery of 50 mAH, the battery is drained in just 25 hours.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Ok, so powering the module through the phones circuit is not a bad idea?
I already have a step down DC DC module, I just need to know where to attach it without disturbing or destroying the BUS circuit.

Best
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Unfortunately I did not find anything.
What I did find however is an accessory which is put on top of the PIN header - a relais module which is activated for a few seconds if somebody rings the door and a much simpler circuit. HERE
With that, maybe someone is able to identify which pins does what and how to use them as a power source.

Thanks!

080af522c2e86e38445faef435f3c16f.jpg 35105b293314be1cf5c1a4b49eee4612.jpg
 

dl324

Joined Mar 30, 2015
8,879
When somebody comes over and rings the bell I have to walk to the door of my apartment and press a button which opens the front door of the complex for a few seconds. I want to automate this by wiring an rf controlled arduino nano so I can wirelessly press the button.
Do you want this remote button press to happen whenever the bell is rung? Only when you're home? Only when you're home and you feel like it?

If you want to always press the button when you're home, you could use a circuit that detects the bell ring and then immediately presses the interior button. You can install a disable switch for when you're not at home or when you want privacy.

No RF gadget needed.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Hey!

Thank you for your reply.
In fact, I want to press it whenever I like, not just when the bell rings...
 

dl324

Joined Mar 30, 2015
8,879
Because I can then unlock the door with my phone if I forgot the key...
What if you forget your phone and your key? What if you forget your key and the battery in the remote is run down?

Seems like your desires exceed your abilities. I'm not interested in helping people with unreasonable expectations.

Signing off.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
Alright, it's not that you gave any helping advice ;-)
In fact, my receiver circuit works very well, I just need a power source, that's why I am requesting help here.
 

Thread Starter

banklooker

Joined Mar 3, 2017
11
No it was not - however I now ran a cable from another room to power it - the circuit works perfectly now!
Thank you! :)
 
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