

Safety Guard For Blind
Helping in need is humanity. In order to help blind people and make their life easier here, the innovative group Dreamlover Technology designs a circuit “safety guard for the blind” using microcontroller AT89c51. This system detects obstacles within 1 meter in the path and alerts the users.
Circuit description
The entire hardware circuit of safety guard for blind is divided into four major sections. i.e. transmitter, receiver, switching section, and the voice processing section.
Transmitter section:- The logic of this section is simple and is build around most versatile IC NE555 (IC1), configured as astable multivibrator to produce frequency about 38 KHz. This is so, because IR module receiver used here works in range of 38 KHz frequency. Timing component of this circuit is resistor VR1 and R1 and capacitor C2, determine the range of oscillating. Where, formula of generated frequency (F) from transmitter section is given by
F = 1.443 / (R1 + 2R2) C2
The output frequency from pin 3 of IC1 is fed to base of transistor T1 through resistor R3. Transistor T1 is configured as Darlington pair with transistor T2 in order to drive pair of IR LED connected in series as shown in figure 2. LED1 is used as transmitted signal indicator and resistor R5 is used as current limiter.
Receiver section:- When transmitted signal from transmitter is obstructed by any object lies in its path then the transmitted signal is reflected. The reflected signal is received by IR receiver module (TSOP1738) and is fed to base NPN transistor T3 through resistor R6 for amplification. Amplified signal is again amplified by pair of transistor T4 and T5 up to necessary level. The output from emitter of transistor T5 is fed through resistor R13 to pin 2 (non-inverting input) of comparator (IC3) where inverting input is connected to zener diode ZD1. The output is taken from pin 7 and is fed to I/O port P1.0 of microcontroller AT89c51 (IC4). The output of pin 7 of IC3 goes high only when non-inverting input is more the inverting input (2.2V).
Switching (Microcontroller) Section:- Here, we use microcontroller AT89c51 for only switching circuit because of availability and to show how to interface an embedded system in a homemade project. Microcontroller section is replaced by any switching circuit. Pin 1 through 4 (P1.0 through P1.3) is used as input port and pin 21 through 24 (P2.0 through P2.3) is used as output port. The output from pin 7 of IC3 is connected to pin 1 (P1.0) and its corresponding output is obtained at pin 21 (P2.0). The output from microcontroller (IC4) is fed to base of PNP transistor (T6) through resistor R18.
The output of transistor T6 from collector is fed through resistor R19 to base of relay driver transistor T7 in order to energize the relay RL1 and is indicated by glowing LEDLED4.
When no signal is applied at input port 1.0, output port 2.0 is high and vice-versa. As transistor T6 is PNP, low at P2.0 conduct it.
Voice Processor:- The entire circuit of voice processing is designed around IC ISD1420 (IC5) which is 28-pin chip by Winbond. The voice message up to 20 seconds is recorded by this IC.
The recording process is done by pressing switch SW4 and the recorded message is played by using pin 23. The condenser microphone pickup the voice message and changed it into corresponding electrical signal connected to pin 17 and 18 via capacitor C13 and C10 respectively.
Pin 14 and pin 15 is connected to headphone jack or loudspeaker through coupling capacitor C14 for playing message. Volume is controlled by variable resistor VR2.
Software:- The source code for safety guard for blind is written in C-programming language.
Click here to download the source code
PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise) |
R1, R2, R9, R18, R19, R20, R21, R28 = 1 KΩ R3, R6, R11, R13 = 22 Ω R4 = 47 Ω R5, R7 = 100 Ω R8 = 15 Ω R10 = 68 Ω R12 = 4.7 KΩ R14, R15, R16 = 470 Ω R17a = 620 Ω R17b, R22, R23 = 100 KΩ R24 = 5.1 KΩ R26, R27 = 10 KΩ VR1 = 2KΩ (preset) VR2 = 4.7 KΩ (preset) |
Capacitors |
C1, C4 = 100 µF/25V (electrolytic) C2, C3 = 0.01 µF (ceramic disc) C5, C6 = 33 pF (ceramic disc) C7 = 0.001 µF (ceramic disc) C8, C14 = 4.7 µF/16V (electrolytic) C9, C10, C11, C13 = 0.1 µF (ceramic disc) C12 = 220 µF/16V (electrolytic) |
Semiconductors |
IC1 = NE555 (timer IC) IC2 = LM7805 (+5 Volt regulator) IC3 = LM311 (comparator) IC4 = AT89c51 (microcontroller chip) IC5 = ISD1420 (voice processor) T1, T2, T3, T4, T5 = BC548 (NPN transistor) T6 = BC558 (PNP transistor) ZD1 = 2.2 volt, 1/4 watt (zener diode) D1 = 1N4001 (rectifier diode) IR LED1, IR LED2 = Infrared LED (5 mm diameter) IRX1 = TSOP1738 (IR receiver module) LED1, LED2, LED5 = Red LED (5 mm diameter) LED3 = Green LED (5 mm diameter) LED4 = Yellow LED (5 mm diameter) |
Miscellaneous |
B1, B2 = 9 Volt (battery) XTAL1 = 3.579 MHz crystal oscillator SW1, SW2 = ON/OFF SPST (Single Pole Single Throw) switch SW3, SW4 = Push-To-On switch MIC1 = Condenser Microphone JACK1 = Jack for headphone connector RL1 = 5 Volt, 100 Ω, single changeover relay |
more intersting project. please send me project with full report on my email cmdzubair28@gmail.com
what can i use behalf
ISD1420 (voice processor)?
are u able to make the project
r u able to make the project
want more information on this project
pls send more information about this project and also send cost details for this project to this mail id swetha.sivanesh@gmail
May you please send more information about your project and the report
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The only details we offer is what is written in the project description page here.
more intersting project. please send me project with full report on my email
..Read more https://electronicsproject.org/safety-guard-for-blind/
can you please emali me a PCB layout of this project including full explanation of how it works with these four separated circuits
, maybe a video at t.mantyi@webmail.co.za
please mail me the coding…………and tell me tht whch other component i use instead of IC5–ISD1420
In connection for the microcontroller has T7 but you do not state what the T7 at the parts list…..
T7 is a BC548 (NPN transistor) or BC558 (PNP transistor)??
pls send this complete project on my email id
INTERESTING! MORE CLUE ABOUT THE PROJECT ON MY E-MAIL PLEASE danielokori4@gmail.com
a very interesting project please send me more about it….
Can you please send me the entire project on my email id – gourabdas366@gmail.com
i am interested in this project.so please send me full report of this project.
where does the “out” in pic 2 lead to ???
+5v means we have to supply 5 volt to circuit in 3 and 4 ah???
ppl wat is source code ???
wat is use of it ???
if it needs to be copied to a chip how to do it ????
PLz Help Me fast i am new to projects in Electronics
Admins plz help me
plz give me good ideas for microcontroler processor projects with complete reports , for good marks and knowledge.
here my email address is, comelate84@yahoo.com
do you have pcb layouts of your circuits? if yes please email me at t.mantyi@webmail.co.za
Plz send more details about this project. I hope to give an additional implement to it.
sir, pls inform this circuit will work for ir proximity sensor purpose
i am intresting in this project so please send me step by step description for this project
i am a student. this website is very helpful for me.
please send me the full project report including program code,design of circuit and circuit working discription
please send me the block diagram of circuit
where can obtain the program of this project..?
i want more details about this project
is there any video for this project……
very interesting project.i want detail information about project.
Plzz say the total cost?
nice project I’ll try
i would like to do this project .plz give me more details about safty guard for blind
super
I realy like this project but i think so difficult and confussing project.
This is a good project idea.pls help me with the source code of it ad it complete diagram in my Gmail at okekekizito980@gmail.com
I need more details about it…
what can i use behalf
ISD1420 (voice processor)?