InterCom / Door Phone

[audioguru]

Make a video of the circuit blowing up when you power it with AC.

 

[Non89]

what can i add to let the user have an authorize to shut down the "slave" when no visitor ?

So that are no more environment sound sent through the "master" and also the master can stop annoying ....

 

[audioguru]

Most intercom calls are dialed then at the end of a call are disconnected.
You don't want the system left turned on so that a person outside at the slave can hear everything at the master and you don't want the master to hear all the noise outside at the slave.

Have a doorbell. When the person inside at the master hears the doorbell then the intercom power is turned on for the call and turned off when the call is finished.

 

[Non89]

Most intercom calls are dialed then at the end of a call are disconnected.
You don't want the system left turned on so that a person outside at the slave can hear everything at the master and you don't want the master to hear all the noise outside at the slave.

Have a doorbell. When the person inside at the master hears the doorbell then the intercom power is turned on for the call and turned off when the call is finished.

yaya, i want intercom at the end of a call are disconnected, person outside at the slave cannot hear everything at the master.....
if i want to have a doorbell , how can i connect doorbell togather with the intercom ? doorbeel output is connected to the "master" or "slave"... and after end of communicating , how i can stop both intercom , so i need to addition a switch off button?

 

[audioguru]

if i want to have a doorbell , how can i connect doorbell together with the intercom? Doorbell output is connected to the "master" or "slave"?

The doorbell is completely separate from the intercom. The person at the master can use the intercom when he wants.

after end of communicating , how i can stop both intercom , so i need to addition a switch off button?

The switch simply connects or disconnects the power supply to the intercom circuit.

 

[Non89]

oic... that mean i need to connect both intercom within same power supply , so i can close both if i m not using ?

 

[Shyamal]

Range ? ? ?

 

[Boncuk]

The intercom is fitted with a latching DPDT switch (PRIVATE) which interrupts outgoing speech when in the position "SILENT".

To avoid outside noise to be heard inside the house use the volume knob. Turn it all the way CCW for zero volume.

When somebody rings the door bell release the private switch and turn up the volume.

You could also use a microprocessor and disable the entire intercom until somebody rings the bell.

You might also want to connect a sound recording module to tell the visitor you are not at home when he rings the door bell.

Boncuk

 

[Non89]

boncuk , does the circuit work well ? you try before?

 

[audioguru]

boncuk , does the circuit work well ? you try before?

the original project is at www.redcircuits.com called Full-duplex Intercom and looks like it will work well.

 

[Non89]

ya... but boncuk edit some part....and the shielded cable connected part is different also....

 

[Boncuk]

ya... but boncuk edit some part....and the shielded cable connected part is different also....

I guess it won't be difficult to recognize the difference between "SW1" and "S1" as well as "Q1" and "T1".

Since Eagle would connect circuits with the same net names different names were used, e.g. "AF-A1" and "AF-A2", both connected at the junction of the transistor collectors (T1) and C3 and T1A and C3A respectively.

The shielded cable connects exactly at the same connection points with the difference, that a three wire shielded cable is used connecting the power supply from the master board to the slave board.

When using a single wire shielded cable connect that to pins2 and 3 of the connector with pin2 being the "hot wire" (labeled "AUDIO" on the PCB design) and pin3 being the shield (labeled "SHIELD").

Use an unshielded two wire cable to connect pins1 (+12V) and pins4 (circuit ground) between boards.

I tested the clarity of the board layout asking my 12 year old stepdaughter where she would connect both boards and her answer was: "just 1:1 as labeled".

Boncuk

 

[Non89]

i m using shield 4-wire cable, so i just connect as shown?

and i need 2 power supply , 1 is for "master" , another for "slave" ??

 

[Boncuk]

You need two cables:

One two wire unshielded cable to connect the 12V power source to the solder pads on the master PCB. Those solder pads are only present on the master PCB and they are located halfway between connector Y1 and C7. They are labeled "+12V" and "GND".

The second cable should be a four wire shielded cable (If you can get 3 wire shielded cable it will suffice as well.)

I redrew the wiring since I don't like thick lines crossing parts and text in a schematic layout.

Additionally to the wires connecting pins I added a small sketch showing the pins labeled MA1 through MA4 and SL1 through SL4 which stand for master and slave.

Using a four wire cable it won't hurt if you connect the fourth wire to the shield.

If that drawing doesn't help you now I'm afraid nobody can help you.

Boncuk

 

[Non89]

i was tried the circuit on board , but it doesn't work well .....

 

[Non89]

any software can let me try the circuit in pc, i want to retry it.....

i can't find the TDA7052A chip at multisim .... the data is not completed

 

[audioguru]

i was tried the circuit on board , but it doesn't work well .....

Please tell us the details about what did not work well. Acoustical feedback? Hiss? Hum? Distortion? Not enough output level? Boomy speakers?

i can't find the TDA7052A chip at multisim

There are hundreds of low power amplifier ICs available. Use a TDA2822M or LM386 instead.
Why simulate a simple audio amplifier when all its spec's are in its datasheet?

 

[Non89]

i try a part at multisim , the voltage is low , same like what i tried at board.... and i get zero output on speaker

 

[audioguru]

Your Multisim schematic shows a transistor with no input signal and its base is disconnected from its base bias resistors. So of course there is no output.

 

[Non89]

wrong post, sorry