I first mentioned Dale Wheat's tinyCylon kit during a post regarding the "new" SN76477 complex sound generator IC. In case you missed it, tinyCylon is a small kit that creates 10 different LED flashing patterns with 5 red LEDs, an Atmel ATtiny13 microcontroller, and a 4.5VDC battery pack. In other words it's an LED blinky PCB—easy to assemble and easy to operate.
While tinyCylon is a nice "stock" kit, I wanted to make my version, well, tinier. In order to shrink this kit down to size, I opted for replacing the LEDs and the battery pack. The result is a really tiny tinyCylon.
Surface mount LEDs were selected as replacements for the kit's T-1 LEDs. Any 0805 package SMD LED should work. Likewise, the all red 3mm LEDs were replaced with three different color SMD LEDs in this pattern: red - green - yellow - green - red.
The 4.5VDC battery pack is way too bulky and cumbersome for my intended diminutive version. A smaller more portable battery supply was needed. Luckily, the ATtiny13 microcontroller is able to support a supply voltage of 3VDC. Therefore, a 3V lithium battery was substituted for the 3-AAA cell battery pack.
Be advised that the substituted 3V lithium battery will not drive the SMD LEDs nearly as bright as the stock 4.5V battery pack and 3mm red LEDs. But in the cool dark confines of outer space (or, my backyard), all LEDs are bright. moo-ha-ha
TIME: 15 MINUTES COST: $9.95 [The kit's price.] + $1.55 [The price of this project's components.] DIFFICULTY: MODERATE [The stock kit is easy, but soldering the SMD LEDs is a more demanding challenge.]
In this modification of the tinyCylon kit, the SMD LEDs and SPST switch are mounted on the underside of the PCB. The ATtiny13, resistor, and lithium coin battery holder are mounted on the upper side. Be sure to leave one of the PCB's screw mounting holes open when you mount the battery holder.
There is a simple technique for soldering SMD LEDs on the tinyCylon PCB. First, add a blob of solder to the square pad on the underside of the tinyCylon PCB. Using your tweezers, orient the LED chip with the anode terminal on top of the solder blob. Reheat the solder blob and the LED chip's anode terminal will gently drop into the molten solder.
Test your solder connection by carefully tweaking the anode connection with the tip of your tweezers. If it's a solid connection, add a small blob of solder to the round pad on the underside of the tinyCylon PCB that is directly adjacent to the square pad (e.g., to the right of the square pad when looking at the LED pad end of the PCB) and connect the cathode terminal to this round pad.
One SMD LED down and four more to go.
After your soldering is complete, examine each of the SMD LED connections and make sure that you haven't accidentally created any metal-to-metal short circuit errors with the battery holder. If everything checks out OK, plop a battery into the holder and witness your nifty SMD handiwork. Take your portable Cylon light show with you anywhere alien cybernetic organisms are likely to roam—like dance clubs. You'll be the life/laugh of the party.
Special Note: BG Micro has just released a breakout PCB for converting the SN76477 complex sound generator IC into a standard DIP layout. The board costs $2.95.