Object avoiding robot without microcontroler

Thread Starter

abdullah8391

Joined Sep 6, 2015
80
hello again!
I am trying to make an object avoiding robot without micro controller. below is the link from where i am taking help.
http://www.engineersgarage.com/contribution/obstacle-avoiding-robot-without-microcontroller?page=1

I am right now designing 555 timer control (part of object). From circuit, 555 timer is being used in astable mode.
But how exactly is it working?
because in astable, it will give continuous output.

In my opinion 555 timer should be used in mono-stable.
is my opinion correct, if not then why?
image from site of 555 timer is also attached. (pin 2 is connected with pin 6, written on site).
 

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blocco a spirale

Joined Jun 18, 2008
1,535
The 555 is configured correctly as an oscillator/astable to pulse the IR LED at 38kHz. The IR receiver has a peak sensitivity at 38kHz so responds to the reflected IR from the LED.
 

GopherT

Joined Nov 23, 2012
7,983
hello again!
I am trying to make an object avoiding robot without micro controller. below is the link from where i am taking help.
http://www.engineersgarage.com/contribution/obstacle-avoiding-robot-without-microcontroller?page=1

I am right now designing 555 timer control (part of object). From circuit, 555 timer is being used in astable mode.
But how exactly is it working?
because in astable, it will give continuous output.

In my opinion 555 timer should be used in mono-stable.
is my opinion correct, if not then why?
image from site of 555 timer is also attached. (pin 2 is connected with pin 6, written on site).
The Stage 1 is only flashing an LED IR emitter at 38k Hz. Nothing more.

Stage 2 (TSOP sensor) is looking for the flashing 38kHz pulse to reflect off of an object (obstacle). When a reflection is identified, the output changes.
 

GopherT

Joined Nov 23, 2012
7,983
But when i calculate frequency by formula, it gives
Note that the drawing in Post 1 has the pins all mixed up - they are numbered correctly but not in the right position.
Your timing resisters are 10k and a 20k pot (adjusted to about 14k of resistance). Your timing capacitor is 1nF (0.001 uF).
 

Thread Starter

abdullah8391

Joined Sep 6, 2015
80
The Stage 1 is only flashing an LED IR emitter at 38k Hz. Nothing more.

Stage 2 (TSOP sensor) is looking for the flashing 38kHz pulse to reflect off of an object (obstacle). When a reflection is identified, the output changes.
thanks...
but where should i connect led IR emitter and tsop sensor.
because it's last figure is a bit confusing... :-(
 

GopherT

Joined Nov 23, 2012
7,983
thanks...
but where should i connect led IR emitter and tsop sensor.
because it's last figure is a bit confusing... :-(
There is no electrical connection. Stage 1 just flashes the IR LED...
...then IR (infrared light) reflects off of a wall or object and back to your detector.
 

Thread Starter

abdullah8391

Joined Sep 6, 2015
80
There is no electrical connection. Stage 1 just flashes the IR LED...
...then IR (infrared light) reflects off of a wall or object and back to your detector.
Yes... And i am asking where is detector connected? On 555 timer with which pin?
 

GopherT

Joined Nov 23, 2012
7,983
thanks...
but where should i connect led IR emitter and tsop sensor.
because it's last figure is a bit confusing... :-(

The InfraRed Light Emitting diode is a device. It is called by its short name "an emitter" sometimes.

This projects works as follows...

The 555 timer and the InfraRed LED are like your thumb pushing a button on a flashlight. All it can do is pulse the light on and off. There is no wires or nerves connecting your thumb to your eye.

Now, in the same dark room, your eye is like the TSOP sensor. it can see the flash of light if the light hits something and reflects back to the eye. If the light hits nothing, then the eye cannot see the light.


Do you understand why it is better to flash the infrared LED instead of leaving it on constantly?
 
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