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Build a device from a schematic (DIY PC board)

I will use ExpressPCB's free software to design the PC board. This is proprietary software from a PCB manufacturer that I have used. The software is beautifully simple and easy to use, so it is great for a hobbyist.

BobK

Jan 5, 2010
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BobK submitted a new Showcase Item:

Build a device from a schematic (DIY PC board)

I will be creating the production PC Board for Steve's thread:

https://www.electronicspoint.com/th...chematic-yet-another-work-in-progress.256843/

I thought while I was at it, why not do a DIY one as well?

So here goes.

I will use ExpressPCB's free software to design the PC board. This is proprietary software from a PCB manufacturer that I have used. The software is beautifully simple and easy to use, so it is great for a hobbyist.

I will be using a laser printer to print out the copper pattern, then using an iron to transfer the pattern to a copper clad board.

I will then etch the board using Ferric Chloride. Next I remove the resist with nail polish remover, drill the holes with a Dremel tool in a drill press jig, and finally assemble the board.

I will post an additional message for each step in the process.

Bob

Step 1. Enter the schematic.

Although you could lay out the PC board without entering the schematic, it is much simpler if you do. The software will know where all the connections need to be and check them for you.

For this project I am using the free software from ExpressPCB, which you can get here: ExpressPCB CAD software

Then enter the schematic. The user interface is quite natural, I find. It has a lot of built-in parts and packages defined and it is very easy to create your own custom components. Here is the schematic as entered to ExpressPCB.

Note that I have made a couple of changes from Steve's schematic. I am going to put 2 little 20ma LEDs on the board, so the series resistor for them has been increased to 220R. Also, I have added a connector for power. You normally would not need to show this on the schematic, but when putting it on a PC board, you must have everything you are going to put on the board.

Also, I have changed the MOSFET to a VN3205 which is a TO92 1A mosfet with 0.3R on resistance that I happen to have in my parts box.


Step 2. Lay out the PC board.

I will not go into detail here because it is a long and laborious process. For my DIY board, I am sticking to 1 sided, which makes layout a lot more difficult. By persisting and moving parts around a lot, I was able to make all the connections with a one-sided board with no jumpers.

Here is the final layout. This may look huge to you, but it is a one inch square! The...

Read more about this showcase item here...
Bob
 
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