|
INDEX |
MY EXPERIENCE IN AUTONOMOUS ROBOTICS | |
|
555 Astable
Multivibrator Astable Multivibrator contd. Astable Multivibrator contd. Astable Multivibrator contd. 50% duty cycle circuit Troubleshooting 555 circuits
|
555 I think everybody knows about IC555. It is used by most of the hobbyists. There is a book named “Engineer's Mini-Notebook - 555 Timer IC Circuits” by Forrest M Mimms which gives so many applications of 555. But in robotics, we normally use 555 for generation of clock and pwm generation. Mostly 555 is used to generate 38KHz to IR sensor.
Figure shows the circuit of an astable multivibrator. The name 'astable' implies that this circuit has no stable state. This circuit will always produce pulse output whose timing can be varied with Ra,Rb,C. In order to test a 555 whether the IC is good or bad, we use above circuit with Ra=10kohm,Rb=470Kohm,C=1uF. So if this circuit blinks the LED, then we can assure that 555 is good. In circuits we normally avoid the connection of pin 4 to Vcc and pin5 capacitor to ground. Pin4,5 are normally left open in most of the practical circuits. But no problems occurred to me till now by leaving this two pins open. Now let's see what is happening in IC555 |
