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dmzoneill
(@dmzoneill)
Active Member
Joined: 1 year ago
Posts: 7
2020-09-10 7:09 pm  

Hi,

Some background.   My partner runs yoga classes and she operates a schedule.  There is a door buzzer that send a 12volt  modulated dc signal on a 12VAC line to the phone handset inside the premises.  A typical user would go over to the phone and press the door release button.

I created a solution that used raspberry pi and a sound detector, to detect the buzzer on the given schedule and then connected it to the door release button

https://github.com/dmzoneill/ashtangayogacork.ie-doorpi

She has to move premises and i would like to improve the design as the sound detector was plagued with false positives. i want to logically connect to the circuit via a optocouplar or something

Intercoms are typically called ZYZ345 (3 4 5 meaning its either 3, 4 or 5 wire setup)

The one i have to operate with is 4 wires: 

image
image

I'm looking for help or feedback on the following design.  I'm a little bit etchy on the component selection.

image

Any feedback or ways to simplify would be appreciated

 

thank you

 

This topic was modified 1 month ago 2 times by dmzoneill

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DroneBot Workshop
(@dronebot-workshop)
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Joined: 1 year ago
Posts: 627
2020-09-10 11:23 pm  

@dmzoneill

First of all, welcome to the forum!

Secondly, I'm a bit confused by the wiring of your relay, it seems to be permanently activated as one side leads to 5-volts and the other side to ground?  Or am I misreading your schematic?

If I understand correctly, what you are trying to accomplish is to allow people to just press the buzzer to let themselves in, but only during a specific time period - is that correct?

😎

Bill

 

 

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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dmzoneill
(@dmzoneill)
Active Member
Joined: 1 year ago
Posts: 7
2020-09-11 8:42 am  

Hi,

yes,i took the door release circuitry out. (as it is confusing)

possibly this is easier to follow.

 

1) user presses intercom button
2) 12 volt modulated dc pulse is sent to the buzzer

2a) pulse passes through the resistor (need to do ohms law here)

2b) optocouplar fires

3) raspberry pi picks up the 5 volt signal

4) raspberry pi checks schedule

5) if class is on active on the schedule then active spdt relay

6) which is connect to the door release, release the door (buzz them in)

image
This post was modified 1 month ago 3 times by dmzoneill

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DroneBot Workshop
(@dronebot-workshop)
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2020-09-11 3:01 pm  

@dmzoneill

Well, I'm still confused by the relay coil wiring, as it still seems that it is permanently connected to 5-volts and ground.

Nonetheless, here are my thoughts:

  • The optoisolator to the input is a good idea. I will assume that the "buzzer lilypad" is an electronic or piezo buzzer and not an electromechanical one. If it was an older electromechanical one then you would need some noise filtering, or you'll get multiple triggers to the optoisolator (which you could always ignore in software).
  • Not sure about the resistor to GPIO 25. The way I see it that resistor should be on the line going to ground, to act as a pulldown.  That would also resolve the issue I keep harping on about with the really always being on. The emitter output of the optoisolator could just connect directly to GPIO 25.
  • Use a second GPIO port to drive the relay. I'm not sure if you are using a relay or a relay module, if it's the former then you might consider using a MOSFET or driver chip as you may be taxing the limits of the Pi GPIO. If you are using a module this has been done for you already.

 

BTW, I took a look at your partner's website, looks like a great business!  From the description of the premises, I see that you instruct people to press the doorbell, and the door will open for 5-seconds, which I assume you'll time with the Raspberry Pi (unless the door locking mechanism already takes care of the delay for you).  And, of course, you'll have it only work during hours when the studio is actually occupied!

Too bad you're in Ireland, I threw my back out a few days ago (I have a herniated disk and a lifetime of back problems) and as I write this I'm wearing two back braces. I could probably use a yoga session right now!

😎

Bill

 

This post was modified 1 month ago by DroneBot Workshop

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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dmzoneill
(@dmzoneill)
Active Member
Joined: 1 year ago
Posts: 7
2020-09-11 4:43 pm  

Hi Bill yes,

I just realised the relay is upside down.. No wonder you are confused :).

I just need good component selection so, i have most of it i believe.

Closest thing to an electronics shop around here in pcworld :S

thanks for the feedback, seem to be on the right path then!

thank you

 

Pa. attached image is the original one with the sound sensor

image

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DroneBot Workshop
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2020-09-11 4:49 pm  
Posted by: @dmzoneill

Closest thing to an electronics shop around here in pcworld :S

Being in Ireland you can probably get stuff from Pimoroni pretty quickly, one of my favorite "candy stores"!

Looks like you also have a temperature and humidity sensor in there, are you also controlling the climate in the studio or do you just display it somewhere?

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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dmzoneill
(@dmzoneill)
Active Member
Joined: 1 year ago
Posts: 7
2020-09-11 4:57 pm  

@dronebot-workshop

i have 4 wireless plugs attached to 4x(3KW heaters). @ see picture

Also infrared transmitter to active the robot hoovers.

the camera is for security.. uses gnu motion to upload video and pictures (on movement) to google drive.

image

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dmzoneill
(@dmzoneill)
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Posts: 7
2020-09-11 5:12 pm  

Sorry to hear about your back


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DroneBot Workshop
(@dronebot-workshop)
Workshop Guru Admin
Joined: 1 year ago
Posts: 627
2020-09-11 10:43 pm  

@dmzoneill

Wow, that's very impressive! You obviously have the software side of things mastered. I like the interface.

Posted by: @dmzoneill

Sorry to hear about your back

It's my own fault, I can go months without any issues as long as I'm strict about doing my daily back exercises, and I haven't been doing them a lot this summer.  I'm exercising now to help heal it and I think it's starting to get better.

You keep the place pretty cool at 18.5 Celcius!

😉 

BTW, 18.5 Celcius is supposed to be the optimum temperature to sleep at. I learned it when I was buying a mattress, they have all kinds of facts about sleep written on the ceiling so you have something to look at when you're trying out the mattresses!

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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dmzoneill
(@dmzoneill)
Active Member
Joined: 1 year ago
Posts: 7
2020-09-14 6:54 am  

Hey,

Do you think this could used to send a welcome message down the intercom.

Hello welcome to AYC. Bzzzzzzzz

https://shop.pimoroni.com/products/adafruit-audio-fx-mini-sound-board-wav-ogg-trigger?variant=1107534013


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