Instructables

Build a binary LED heart decoration (Blinkenheart)

This is my first instructable, so definitely send me feedback. If I can make a schematic that isn't terrible, I'll add it in here.

I'm just starting to learn some basic electronics and a friend wanted to get something special for her fiance for Valentine's day. Perfect timing! So, I made up the parts list, waited for them to arrive, and started building. The unit consists of 32 red LEDs, a 555 timer circuit and a binary counter, along with a bunch of supporting components and some creative wiring.

This was my first major electronics project and I certainly learned a great deal from it. Of course, if I already knew everything that I learned, I might not have been quite so eager to begin it... It took me a lot longer than I had expected it to, but I don't regret doing it. If I have any reason to do this on a larger scale, I am seriously thinking about prefabricated circuit boards.

The end result is an array of 32 LEDs that form a heart, piece by piece, and hopefully will make a nice desktop ornament.
 
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Step 1: Parts list

The first step for me was to prototype small parts of the project on a breadboard. I used an online calculator at http://freespace.virgin.net/matt.waite/resource/handy/pinouts/555/index.htm to determine the values for my timer and used Ohm's law to determine what resistors I would need so the battery doesn't drain too quickly or burn out my LEDs.

I bought almost everything from Mouser (toggle switch was from Radio Shack), so I have all the part numbers available, if anyone wants, I'll post them in here, but they should be available anywhere. The resistors in the Display section are partly for current limitng and partly for convenience. I may have gone insane if I had to cut and strip that much wire.

Do yourself a favor and don't buy a package of 7 DIP switches and thing you are going to be clever and cut them into pieces and salvage 4 individual switch elements from them... Buy a toggle or latching pushbutton switch and keep away the grey hair and premature baldness.

I was a little annoyed by the cost of the protoboard in relation to the other components, but I was impressed with the quality, so I felt better about trading the cash value of a fast food sandwich for it. :-)

Here's the parts list:

Breadboard (for prototyping)
Soldering Iron (20W-40W)
Standard rosin-core solder
Wire cutter/stripper
Diagonal cutter
18-20 gauge wire for prototyping and final construction
3M/Nexcare Micropore(tm) Surgical Tape, gentle paper tape, masking tape, gaffer tape, or your favorite unobtrusive adhesive
Massive amounts of free time and patience

- Plaftorm:
1x standard 0.100" pre-drilled protoboard

- Timer/trigger section:
1x 555 timer chip
1x 0.01 uF ceramic capacitor
2x 1K Ohm 1/4 W resistor
1x 470 uF electrolytic capacitor

- Binary counter section:
1x SN74HC590AN or similar binary counter

- Display:
32x red frosted LEDs, T1 3/4 (5mm) size
8x 2N3904 NPN transistor or similar small-signal transistor
8x 56 Ohm 1/2 W resistor
8x 82 Ohm 1/2 W resistor

- Power:
1x 4 AAA battery holder
1x 100 uF electrolytic capacitor
1x PCB toggle switch or latching pushbutton
carebare474 years ago
Cant find anywhere near me that sells the binary counter (or anything similar). Any ideas? =]
dsman1952766 years ago
good job! i am going to add this instructable to my "how to count in binary and hexdecimal" instructable!
certron (author)  dsman1952766 years ago
Thanks! I'm pretty happy with how this turned out, even if it did take a long time.
yea. looks really cool. i just dont have that much LEDs on me.
certron (author)  dsman1952766 years ago
I used mouser.com part 859-LTL-4213 and bought 70 of them for $6.30... (I still have to make one for my girlfriend... I'm surprised she hasn't found out yet!) Like I told my friend, who originally wanted water clear case, this is an ornament, not a flashlight, so we went with the frosted case.
hmm. i need to buy some!!!! :) p.s. my school is closed!!!! yay!!!!!