Instructables

Came across this circuit on some gallery and got curious. what does this circuit do?

I found this circuit while on some image gallery but I want to know what it does! I did some research and does this circuit have anything to do with truth tables? 

So could you please tell me, what the purpose of this circuit? and whether truth tables are involved?

Thanks
Dan1001

Picture of Came across this circuit on some gallery and got curious. what does this circuit do?
Its a cicruit that generates PWM with a frequency of ~1.7Hz

The counter counts
0,1,2,3,4,5,6 and resets to zero

Q goes high only on 5, so this is a 20% PWM circuit.
dan1001 (author) 2 years ago
so saying that. could it be a counter/stop clock, Because I might be wrong but A counts for 1, B = 2, C=4, D=8. So would the counter only display up to the number 15 and then because a reset is involved, it can be reset back to 0?? Or do you have anymore suggestions? I am kinda new to this and want to learn a bit more about this circuit.
gmoon2 years ago
Any time logic gates are involved truth tables are useful.

The left side of the circuit (NOT gate, cap and resistor) looks like a simple oscillator. It feeds the input of the counter. The E pad looks like an undivided output, though not digital.

The counter and the two AND gates form a frequency divider. The lower AND gate flips on the count being 5, and the upper AND gate resets the counter on the next cycle.
dan1001 (author) 2 years ago
could it perhaps be used for a clock or a stopwatch??
Its more of a basic block diagram then a circuit. This could be the block diagram of a simple IC. No way to know for sure unless someone has actually seen this in reference to a specific item.