Twinkle, twinkle little star


I found in my storage/yank-box/whatever... this little star made long time ago.
As you can see at the circuit side of the board it's made 1982!
There are 12 LEDs flashing with different speed. It is built around two 74LS14.
For each LED there are a resistor, a capacitor, a transistor and a schmitt trigger.
Common parts are a 7805 and some decoupling capacitors. Feed it with 8V or up. Not
too much as the 7805 has to burn up the difference.

Click on the images to enlarge them.






Schematic


Part list for one of 12 circuits:
1/6 of a 74LS14
BC558 (PNP)
10 microF
The resistors are in the range 15k - 100k
And of course the LED

Use different resistor values for the oscillators to make them flash
with different speed.

A funny thing is that they disturb each other so they does not flash with a
constant speed.


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