Thursday, 2 October 2014

Light Following Robot

Light Following Robot Using 555 Timers.

I actually made this towards the end of March, i became interested in using integrated circuit and micro chips to make stand alone projects as they are cheaper than using an arduino for each project.

There are two configurations for 555 timers mono stable and astable. For this project monostable is used. A great website explaining how they work.

Monostable Operation

"Unlike the astable, which has two unstable states and so continually switches from one to the other and back again, the monstable has one stable state and one unstable state.
When triggered by a suitable pulse at its input (pin 2) it switches from its stable state, in which the output is low, to its unstable state where its output is high. This state exists for a time controlled by the values of R1 and C1, and at the end of this period the output switches back to its stable (low) state. Its primary use is therefore to produce a set time delay, initiated by an input pulse."

Quote and image taken from

Building The LFR

I followed this instructables it was the most simple one i could find, there are other tutorials out there that use potentiometers to set the sensitivity of the LDR's and hence the speed of the motors.


The idea worked however the LFR didnt really move.. i didnt have proper wheels, i cut some out from cardboard. Also the fact i didn't use motors with gear boxes and gave the motors more voltage than they needed resulted in not much torque.

For my first play with 555 timers i am still happy with the out come. Ultimately i decided that having a mobile platform that i could add sensors to and program would be a better use of my time and didn't continue with it.

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