Circle of Lights, Part Two

Continuing with the Circle of Lights...

At the end of Part One, I had just dropped the resist laden copper-clad board into an Ammonium Persulphate bath.

Here are some time-elapse photos of the etching process...

Slowly but surely, the solution removed the unprotected copper atom by atom. I had almost expected the Cu to come off in pieces...but I was surprised to find it simply disappeared.

As the copper was removed, the Ammonium Persulphate started becoming bluish-green in coloration. I suppose this is due to the oxidation of copper that must occur in the chemical process of etching.

Here you can see the excess copper almost fully dissolved off the phenolic board. The dark splotches are remnants of the copper.

Here is a view (opposite side) of the etched board. Notice the very bluish chemical in the bottom of the tank, and the etched design showing through the back of the board.

The whole process of etching (time in the tank) took approximately 20 minutes. The solution was most likely at room temperature throughout the process, and the 'agitator,' a small aquarium pump, was run throughout that time.

Here is the still-resist-laden board post tank.

A simple acetone application removed the remaining resist (toner) from the board. The copper traces showed some signs of etching, as if the toner allowed some of the copper to be removed. I checked the traces with a VOM meter for continuity, and all registered minimal resistance.

I used a small drill press and a 1/16th drill bit to make the necessary component holes.

After drilling, I grew tired of worrying about further copper oxidation and decided to tin the traces. At this point I remember I forgot to mention something...small, but perhaps necessary.

When I first opened up the copper-board packaging, and before applying the toner from the TTS paper, I made sure to clean the board with paper towels, cotton swabs, and Isopropanol.

Basically, it is said one should clean the copper of the board with strong alcohol before use to limit oxidation effects in the future, and to remove some of the unseen oxidation present on the board. I made sure to do this at each step: from toner application to pre-tinning, to post tinning flux removal.

I wanted to have the LEDs contained within an enclosure, and use Visual Communications Co's LED LitePipe® to transport the light to the chassis exterior.

This required a fair amount of in-accurate engineering on my part. I remember stuttering to myself in the electronics store trying to guess which PCB standoff size to use....

I had to figure for the chassis depth, the 5mm LED height, the board thickness, the LitePipe length (1/2") on the spot with a scratch sheet of paper and my cell-phone calculator. I ended up using a metric approach, converting and subtracting the combined theoretical internal board-height-limit of the design (the LitePipe + approx. LED height off board +/- a few mm for tolerance) from the total chassis depth. The answer I got was close to 1 1/2". I purchased both 1 1/2" and 1 1/4" standoffs. I ended up using the smaller ones, and as you will see, lifting the LED bases about 4 to 6 mm off the board to "meet" the LitePipe.

I used a copy of the original design to plot out where I need to locate the LitePipe.

By God's grace I managed to drill the holes close enough to where the LEDs would be located internally. Also shown are the On/Off switch, the Reset switch, and the Dimmer Pot.

This photo shows the beginning of through-hole component placement. Above the board you can see the actual bread-board experiment that I used to realize the original circuit.

Above and below show the component side and solder side of the board. As a side note, and in relation to the current measurements listed in part one (in schematic,) I hand-matched each one of these resistors to the closest possible range I could. In other words, out of 45, 5%-tolerance carbon resistors I was only able to find 12 in a range from 588 to 593 Ω.

I'd also like to add that the view show above is not encouraged. I did this to solder the resistors en masse.

Here are my favorite parts of this experiment. The LitePipe.

Each plastic rod extends into the chassis and meets (approximately) with the 12 LEDs shown below. See the topmost photo of this blog to view the inner workings of the device (board, lights, and standoff.)



When finished, I had a rather impractical yet colorful light show.

I thank God for seeing me through this project, and helping me to climb this mountain.

To Him be all glory, honor, and praise.

Thanks for tuning in-