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by Salah
Sat Nov 03, 2018 4:10 pm
Forum: Beginners
Topic: Use Pi Zero as an intercom handset
Replies: 6
Views: 596

Re: Use Pi Zero as an intercom handset

Andyroo wrote:
Thu Nov 01, 2018 8:51 pm
Replace the speaker with headphones as a test.

These will cut out any sound feedback.
The speaker is a handset ear speaker so it acts like a headphone already.
I added on my first post a basic scheme of the connections I've made to make things clearer.
by Salah
Fri Nov 02, 2018 11:27 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Yes you could use that opto isolator , you need a resistor to limit the current flowing through the LED, because if you just connected 3.6V to the LED you would burn it out. so using the opto isolator you selected you now need a 330Ω resistor. You will also need a diode connected in reverse with th...
by Salah
Fri Nov 02, 2018 10:41 am
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

I really don't understand how the Pi would provoke the audio loop but the intercom handset on its own wouldn't.

I ordered an audio amplifier and I will connect a speaker to the Pi audio output.
I think this would work but this is a workaround :(
by Salah
Thu Nov 01, 2018 7:59 pm
Forum: Beginners
Topic: Use Pi Zero as an intercom handset
Replies: 6
Views: 596

Re: Use Pi Zero as an intercom handset

Andyroo wrote:
Thu Nov 01, 2018 5:19 pm
You could try a set of headphones - not sure if the impedance would be correct but may prove if the sound is feedback.
What do you mean ?
How do you want me to try with headphones ?
by Salah
Thu Nov 01, 2018 6:58 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Hmm! the microphone might be polarised (is it an electret mic?). Try swapping the speaker wires instead. I googled electret mic and mine looks like this: https://www.jayconsystems.com/media/catalog/product/cache/1/image/x480/9df78eab33525d08d6e5fb8d27136e95/J/S/JS-0001_7.jpg So I think it is an ele...
by Salah
Thu Nov 01, 2018 1:38 am
Forum: Beginners
Topic: Use Pi Zero as an intercom handset
Replies: 6
Views: 596

Re: Use Pi Zero as an intercom handset

You most likely are suffering from audio feedback where any noise picked up on the mic is sent to the speaker where it is picked up by the mic etc etc... I would think the old intercom turned off the speaker when you pushed the ‘talk’ button. You will have to check the software to see if it can emu...
by Salah
Thu Nov 01, 2018 12:17 am
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Try swapping the polarity of one of the devices, either the speaker or the microphone and see if that cures the problem. I've just swapped the polarity from the microphone by swapping the wires that I had soldered to the jack connector: I can hear the communication on the phone but I can't hear any...
by Salah
Wed Oct 31, 2018 10:38 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Because the audio circuitry of the handset by its self was carefully designed so that the microphone audio and speaker audio were 180 degrees out of phase and at an amplitude that any locally fed noise would cancel itself out. The audio circuitry of the USB audio dongle was likely in-phase and ther...
by Salah
Wed Oct 31, 2018 3:37 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Ah, Domoticz is a very powerful guy, Blynk is just a baby. Your separate thread seems talking about the positive audio feedback thing. You need a special circuit to eliminate the feedback. Interesting, it sounds like it might be it but then I don't understand why this Larsen effect didn't occur at ...
by Salah
Wed Oct 31, 2018 12:39 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

You might consider Blynk. And if your phone is too far away from the Rpi, you might need an external antenna. I use Domoticz to control pretty much everything in my home and it's working fine so I think I'll stick to Domoticz for now and maybe try out Blynk later on, it seems pretty much similar to...
by Salah
Wed Oct 31, 2018 12:03 am
Forum: Beginners
Topic: Use Pi Zero as an intercom handset
Replies: 6
Views: 596

Use Pi Zero as an intercom handset

Hi, I'm working on connecting my old flat intercom to the raspberry so that I could receive a call on my smartphone when someone rings at the entrance door. The intercom handset has 3 wires: blue & red connected to the speaker blue & white connected to the microphone IMG_0643.jpg IMG_0548.jpg To set...
by Salah
Tue Oct 30, 2018 11:24 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

What are you referring as the intercom switch ?

I like you idea of powering the VOX with the intercom to avoid false triggers.
I could wire the VOX directly to the speaker right ? Though I'm not sure that 3.5V would be enough to power it on.
by Salah
Tue Oct 30, 2018 3:46 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

A VOX should work to do the thing. Put the VOX input next to the speaker, adjust the sensivity, and send the groomed binary signal to the RPi. No need to cut wires. You can make a VOX, just do a search using your favorite search engine for "audio activated switches circuit' and build one to suit yo...
by Salah
Tue Oct 30, 2018 1:16 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Wouldn't it be easier to look for the signal that triggers the oscillator circuit driving the ringer speaker, because that will be a simple Voltage level change surely? Much easier to interface to a GPIO. On the speaker, this is also a simple voltage level change ? What's the difference exactly ? I...
by Salah
Tue Oct 30, 2018 12:24 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

I am also confused. :? If you want to know when the speaker 1 rings, why not connect the 3.5mm plug to the speaker 1, and forget the other speaker 2? The main purpose of this project si to get notified on my smartphone when I'm away and the intercom rings. I also want to be able to communicate with...
by Salah
Mon Oct 22, 2018 12:02 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Let me see, if Rpi's audio input jack can get the signal from the 3.5mm plug connected to the intercom loudspeaker, then you can just write a simple program, say, in python, with the help of so many python audio libraries out there, to do what you want. In other words, there is no extra hardware re...
by Salah
Mon Oct 22, 2018 8:20 am
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Thank you for the explanation tlfong01, I think my intercom is lightly different from the one on the diagram. Mine has a handset with a separate microhpone and speaker. The speaker I want to wire to the pi only buzz to alert me someone wants to come in, there is no audio voice out of it. I attached ...
by Salah
Sun Oct 21, 2018 10:42 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Hi tlfong01,

I don't see any original relay module in the intercom.
The thing you labelled "A", is indeed a relay, but one I added to control the door opening switch with my raspberry pi.
by Salah
Thu Oct 18, 2018 3:58 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Thanks pcmanbob, this is pretty much clear to me now ! ;) I'll order the opto isolator and let you know. The link about pull up / pull down circuit says I don't need resitors (10K & 1K) since it's already integrated within the Pi when setting up the PIN to GPIO.PUD_UP / GPIO.PUD_DOWN mode. Is that r...
by Salah
Thu Oct 18, 2018 11:57 am
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

Exactly, I just want the raspberry pi to know when a sound is being played through the speaker. Should I look for a specific opto isolator ? I found this but I don't know if that will do the job: https://www.aliexpress.com/item/50pcs-PC817-EL817-817-817C-FL817C-PS817C-DIP-Optocoupler/32835155712.htm...
by Salah
Wed Oct 17, 2018 8:55 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Re: Detect current on Raspberry pi

I want to monitor the speaker part of the circuit (cf attached picture).
I've just measured the voltage on the speaker when it's ringing, I get something between 3.4V and 3.6V.

Please let me know if I can give you some other information.
Thanks
speaker.jpg
speaker.jpg (151.11 KiB) Viewed 2383 times
by Salah
Wed Oct 17, 2018 2:43 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6323

Detect current on Raspberry pi

Hi, I'd like to test with my raspberry pi if there is a current flow on an intercom speaker. The purpose is to get notified when someone rings at the entrance door. My guess is that I should plug the speaker circuit to a GPIO pin and read this pin constantly to know if the intercom is ringing. I kno...
by Salah
Mon Aug 31, 2015 3:23 pm
Forum: HATs and other add-ons
Topic: NRF24L01 RF Transceiver
Replies: 252
Views: 133990

Re: NRF24L01 RF Transceiver

Hi everyone, I'd like to use the NRF24L01 RF Transceiver in order to mock / copy the remote control of a quadcopter. The remote control is a simple one which use radio message at 2.4Ghz ( see product details ) My idea was to use the NRF24L01 in receive mode and test each button of the original remot...
by Salah
Sun Nov 03, 2013 5:54 pm
Forum: Raspbian
Topic: Can't boot my pi
Replies: 1
Views: 498

Can't boot my pi

Hi everyone, I have a Raspberry Pi model A with a Raspbian installed on the SD card. It was working well for few weeks but now when it boots, it get stuck at this point of the booting process : [ ok ] Starting enhanced syslogd: rsyslogd. From this point, nothing happens, I can type some text but tha...
by Salah
Mon Jul 09, 2012 1:09 pm
Forum: Other
Topic: Is it possible to plug a USB Dongle with Raspbmc ?
Replies: 1
Views: 1371

Is it possible to plug a USB Dongle with Raspbmc ?

Hi everyone, I got my Pi fews days ago, I installed Raspbmc on it and it's pretty amazing how fast it responds for such a small device. I used a cable connection so far but I'd like to plug my TrendNet N150 USB Dongle to use my wireless network instead. I tried to get some infos on Google and it see...

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