Home Brewing Ham Gear - PC Boards
There are several methods you can use to assemble circuits at home. I like to use printed circuit board material in various ways. Surplus or new board material can be obtained inexpensively. I was lucky enough to find a fairly large box of various blank boards at a hamfest last year and some at a surplus store in Utica NY a few years back for a dollar a pound. If you have to buy new board, it still doesn't cost a lot. You can just solder components right to an unetched copper back plane like in some of the rigs I have here. Usually there are enough parts that are going to connect to ground anyway to hold up the rest of the circuit away from the board. If you need a place to mount a component that isn't grounded you can use a component such as a very high value resistor or just cut a small section of circuit board and either glue or solder it to the unetched board, this is known as "Manhattan" style construction. You can also cut away a small section on the main board to make a little island of copper that is isolated from ground. You can see where I did this if you look closely at my two "ugly" rigs. Mounting parts on a board this way is typically referred to as "ugly" construction, for obvious reason!
If you would like something that looks a little nicer, you can make your own printed circuit board. The basic concept is that any exposed copper will be removed chemically and copper that is covered by "resist" is left behind. Different things can be used as resist, the most basic ink from a marking pen. There are also pens made just for this purpose, called "resist" pens, aptly enough. To use this method, simply draw up a pattern using a permanent marker or nail polish right on the board and then etch away the uncovered copper in some ferric chloride solution. The chemical can be picked up a Radio shack store for about $4, and is enough last me a couple of years and several projects. Two very handy tools that most of us already have can be used to make some very nice looking boards. These tools are your computer and ink jet or better yet, laser printer. For the small LM386 amplifier boards that I have here, I used a computer program called "Bpecs", from Best proto on a laptop and a laser printer. This is a program that I happen to like but there are many others you can use, including just using "Paint" that comes with any Windows computer. I found a web page that explains exactly how to do this with good results http://www.keirle.fsnet.co.uk/pcb.htm.
Once you have your pattern ready, you have to transfer it to the board somehow. For this, I use a special coated plastic called "Press-n-Peel". It sells for about a dollar a sheet and comes from Techniks, Inc. http://www.techniks.com . You can print to it from a laser printer or print your pattern on paper, then use a photocopier to print on the coated plastic. You can't use an ink jet printer to transfer directly to the Press-n-Peel. The toner from a copier or laser printer is what makes this system work, it becomes the resist coating for the board. A clothes Iron is used to transfer the pattern to the board. The instructions with the press-n-peel give you more specific instructions for doing this.
Once the board has the resist on it, it's ready to etch in the ferric chloride solution. Ferric chloride is messy stuff by the way and will stain anything it gets on permanently. I use a very deep utility sink and old clothes when doing this. Etching takes between 20 and 45 minutes with fresh etchant solution. When this is done, leave the resist on the board while you drill the holes, a #60 drill bit is usually a good size to use. Cut out the board, clean the resist away with some abrasive such as Scotchbrite and you should be ready to melt solder and mount some components. Keeping the board very clean with Scotchbrite or steel wool and possibly some alcohol, before you apply the resist and then after the etching is done will give you good results.
Here are some web links, which you might find helpful.
Pete's Homebrew page - Here is a good explanation of how to use Windows Paint to layout a board.
http://www.keirle.fsnet.co.uk/pcb.htm
EI9GQ built his own multiband SSB transceiver, the plans are on this page:
A homebrew synthesized receiver covering 300 khz to 30 mhz
http://members.aol.com/gapershi/radio.htm
Some nice ideas for photo etching.
http://www.pconline.com/~rohrwerk/k0jd/
Dan's small parts, misc parts including pc board material
Best Proto pcb and schematic design software
VE3ERP Hamcalc software
http://uhavax.hartford.edu/eetsw
73 de Fran Flynn KM1Z Feb 17 2001 - fflynn@adelphia.net
This page has been accessed
[an error occurred while processing this directive]
times since 23 February 2001
It was last updated on
Wed, 26 Jan 05 at 0332