Happy Face - flashing light effect

I made this device in August 2003. An idea for this toy came to my mind when I was lying sick in a bed. It is just simple flashing effect. When I recovered I decided to send it to electronic magazine "Elektronika dla Wszystkich" where it was published :D.

What is this for?

Answer is simple: to make happy or at least make a person smile to whom it is presented. This device was built two years ago. First version, I sent to electronic magazine, but it was rejected from publication because of mistakes in design. However, it was warm welcomed, what encouraged me to make necessary corrections. When I finished, I sent it again. In first version, eyes blinked only once after smile spread. Public opinion (family and friends) said, that it would be better if they blink independently. This is how it works in new device.

How does it work?

Idea is simple and based on classic connection of two popular semiconductors (NE555 and 4017). Square wave generator produce a signal dependant to value of PR1, R1 and capacitor C2. Signal from output 3 is delivered to clock input of 4017. Each impulse increment counter and results shifting logic 1 on its outputs. To first three output I have connected bases of transistors. When fourth impulse appear it will be delivered to reset input of this counter and counting process will start again. Logic one on output switch on transistor and makes LED light. Circuit including resistor and capacitor, producing RESET impulse on power on turned out to be unnecessary, because random start point doesn't brakes an effect.

@ndrew1980 2016-06-30
Widziałem go w gazecie. Pozdro.

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NE555, CD4017, Happy Face, Efekt świetlny LED

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