Arduino Teaches Old Coder New Tricks

The sponge and ferric chloride method works extremely well, etching the same board in a couple of minutes. In the past, I used ferric chloride to etch boards by placing them into a bath of ferric chloride. Even with agitation, etching a board could take ten minutes or so. The sponge and ferric chloride method accelerates the etching by continuously rubbing the surface with a sponge soaked in ferric chloride. The rubbing removes the oxide layer that continuously builds up, permitting the ferric chloride to get to the raw metal and thus accelerate etching. Instead of a tub of etchant, a couple tablespoons is all you need, which will make a bottle of ferric chloride last for a very, very long time. The technique is simple. Don plastic gloves, pour a couple tablespoons of ferric chloride into a small container, soak a small piece of soft sponge in the ferric chloride, then continuously and lightly rub the saturated sponge on the PCB. In a couple minutes, the board will be finished with little mess and little ferric chloride to dispose of.

My final product (after three versions), a single-sided ATtiny84 version of the project, is shown in Figure 11. Given that the board was single-sided, nine jumpers were required, which are the wires you can see on the component side of the board.

Figure 11. Final Etched ATtiny 84 Board

Commercially Made PCBs

In addition to making my own PCBs, I also had commercial boards made by a panel aggregator. A panel aggregator is a service that aggregates boards from many sources, filling up a cost-efficient-size printed circuit board panel and then breaking up the completed panel for delivery. Several such companies support the hobbyist community.

Figure 12 shows my Attiny85 design mounted to a 16x2 LCD.

Figure 13 shows my Attiny84 design mounted to a 16x4 LCD.

Figure 12. Commercially Made ATtiny85 Board

Figure 13. Commercially Made ATtiny84 Board


Source Code and Hardware Files for the vt100lcd (interested readers can pull down the files and create their own micro-terminal):

The Arduino Project:

The Wiring Project:

The arduino-tiny Project:

Thomas Fischl's USBasp Web Site:

Avrdude Device Programming Software:

The Fritzing Project:

The gEDA PCB Development Project:

Symbol Creation:

Footprint Creation by Stefan Salewski:

"Circuit Design on Your Linux Box Using gEDA" by Stuart Brorson, Linux Journal November 2005:

Using gEDA, by Iznogood:

Getting Started with PCB:

gsch2pcb Tutorial:

gschem → gsch2pcb → PCB:

Circuit Simulation using gEDA and SPICE—HOWTO by Stuart Brorson:


Edward Comer is retired from the telecommunications industry, having worked for the real AT&T, BellSouth and Numerex Corp during a 30-year career.


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Thank you for teaching us

Jasa kontes's picture

Thank you for teaching us this trick. This trick is very useful.
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You stirred my curiosity

Hosting Dude's picture

You really did. Never been interested in playing with hardware stuff. Been a web developer for years, never looked into hardware programming and Arduino and stuff like this. Now I want to learn it lol

Good writeup on this, keep up the good work mate

Hosting Dude

I want to learn Arduino

tempo's picture

I want to learn Arduino projects. maybe by reading this article can help me. tempo

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Anonymous's picture

Thanks for share this

terbaru's picture

Thanks for share this article. I think Arduino projects is amazing. berita Indonesia

Nice one

RUSH PCB UK's picture

Thanks for sharing your ideas and thoughts, i like your blog and bookmark this blog for further use thanks again…

It didn't take very long to

Anonymous's picture

It didn't take very long to remove the mental cobwebs and get into the elegant simplicity of the Arduino Project. Years ago, when I built microprocessor projects, the underlying system code always was the problem. Before I actually could write my application, I had to develop or adapt systems-level code to interface the application-level code with the underlying hardware. Cleaners London


samatha0045's picture

I discovered your blog so far ... much information to improve our space! So thank you and have a nice day!
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The link to the source code

Anonymous's picture

The link to the source code and design schematics just refers to the google code homepage :)


Karl A.'s picture

What a great article!
Are you familiar with They have many Arduino projects. I think this would be a great submission.