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Competition #2: Entries

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The only thing posted to this thread will be contest entries for the

MHLDC: Mini Holiday Light Display Contest​

All other posts will be deleted.

Post questions regarding the contest in the original MHLDC thread.

Voting will be done via poll after the build period closes.

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and here is my submission:


This is how make stars twinkle:

Using an MCU you'll be faced with the problem of generating random numbers. The easiest way is using a dual timer with two different frequencies and no integer division factor between freqencies. This example uses 350Hz for the clock and 180Hz for the clock inhibit signal. The decimal counter is inhibited at irregular intervals thus producing pseudo random numbers at its outputs.

This way the HCF4017 can be used to connect 11 LEDs, (including the carry out). The twinkling varies in a very large range (from pseudo forward via any constellation up to pseudo backwards)

Attached are the schematic, a PCB-layout, Eagle files and the photo of the sample circuit. (The LED carrier is a standard industrial chip carrier for SMD packages with lots of holes to place the LEDs in any desired location)

Be advised that the circuit doesn't contain a current limiting resistor. A 390Ω (for 12V supply voltage and Uf=3.5V) resistor in the ground connection will suffice since there is only one LED lit at a time.



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Here is my mundane entry. A schematic of my 20-year-old Christmas light chaser, originally designed to safely handle 50 lights per string. It can handle more than that, with proper safety precautions followed and being realistic. This same circuit was later modified to become a name-in-lights project for seven lucky female recipients, all are long since gone their separate ways from me.
The video is on VHS, and cannot be uploaded in time for viewing. The tape is in a remote location, and I haven't attempted to upload video yet.
This is a non-uC entry.


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Fairground carousel

I started this a few days ago before I knew you were running this comp, so its now finished (well finished enough for my original idea!).
The idea came as an extra visual attraction for Christmas, and it is simply a fairground chair lift display.
I manufactured the whole thing from paper (printed with the decorations!), and a piece or two of cardboard.
The mechanics consist of a converted servo-motor as a slow speed controllable drive for the chair lift. The chairs are lifted up and down by means of a lightweight line that runs down the central column to the motor drive.
The speed of the lift is varied and the chairs are stopped occasionally to simulate people getting on and off, etc.
Nothing very clever, but looks pretty.
The motor and the chasing LEDS are driven and controlled by a PIC 16F684 (one of my favourite Pics.).
short Video attached. YouTube - thisone.mov
I posted this in December but in wrong place.
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