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How to Design Digital door phone by PIC

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mf1364

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Hi every body
I want to design a Digital Door phone Approximately same as ones in the shopping nowadays and I want to control the action of circuit with PIC so Dose any body can help me ? or dose any body have primary schematic for the analog part of this circuit ?

Any schematic of digital door phone or at least just the audio circuit . any link or pdf and so on is my favorite , thx
 

Circuit becomes difficult if distance required is more how much distance you want..
 

you can use a laser based system. The light emitter on one side and the detector on the other side, obstruction causes a relay to be operated, turning on the motor required to open the door.
 

arbj said:
you can use a laser based system. The light emitter on one side and the detector on the other side, obstruction causes a relay to be operated, turning on the motor required to open the door.
Click to expand...
please explain more and give schematic .
 

Hi KaK111
thanks for your schamatics link I checked them and now I did a little change at one of them and I like to know your idea about it View attachment doorphone.bmp
 

Resolution of the picture is so small that cant see what is the type of amplifier ic.
 

Schematic looks good

C1 is needed for mic. signal input
C2 is for mute button
C3 and C4 work as phase shifter for attenuating signal to local side speaker amp
( minimize acoustic feedback)
C5 attenuate higher frequencies
C6 , C7 power supply filters
250µF needed for separate DC from speaker
amp. pin 5 to gnd , 50nF and R=10 , for eliminating parasitic oscillation
for setting amplification you need 10µF and some R between pins 1 and 8

look page 3.
**broken link removed**

amplifier without large speaker capacitor for ex.
**broken link removed**

more you find with google e.g. ......audio amp 1W schematic

KAK
 
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    mf1364

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thx , and should I use the exact capacitors voltage that has wrote in the picture ?
 

For supply voltage 9..12Vdc , i suggest capacitors rated at 25V
( for 9 volt battery 16V is ok , but still use 25V rated )

KAK
 

Thx , I did it but it doesn't work !
 

Circuit has two blocks : microphone amp and speaker amp
First you should check which block fails.
Do you have oscilloscope or universal Volt meter.

Have you checked that wiring is as in drawning , once more.
What is supply voltage value?
 
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Hi
I just have volt meter but don't have oscilloscope , and I am using 12V DC as power supply . could you do me a favor ? and change the circuit in this way that each circuit works separately . you know I want to test each circuit with its mic and speaker first , and when i could hear the voice in each board then connect the boards together as intercom schematic sheet .
 

You should measure these dc voltages in circuit

Door_Phone_test_01.jpg

Tell me the values A, B, C, D and E

Take out wire D from potentiometer side
and when power is on tap this wire with finger tip , you should hear 50Hz hum from speaker.

Mic. amp. test :
you should find small audio amp. e.g. active pc-speakers

connect this test amp. input gnd to gnd
input hot wire via 20...100nF capacitor

1. to mic. hot wire tap mic, what you hear.
2. to transistor base, tap mic. , what you hear.
3. to transistor collector, tap mic. , what you hear. (Is this louder = amplified in transistor)



KAK
 

Hi
Finally I could run the circuit and know I want to connect each circuit together , can explain more electrically , about this circuit , like how we should calculate the amount of each capacitor ? I mean why c1 = 100n ? how this amount is calculating for this capacitor and others ?
 

Hi Kak
eventually , I achieve my intercom circuit , in the next step I want to remove the connecting wires between two intercom circuits and transmit/receive sound wireless so do you know any module or IC that can help me? , what' your idea about simcom ICs ?
 

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