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Another Analog Discovery Breadboard Adapter

Blog Post created by dmercer Employee on Feb 20, 2013

Another Analog Discovery Breadboard Adapter

In a previous blog I proposed constructing a breadboard adapter PCB for the Analog Discovery module. That approach required ordering a custom board design from a source like batchpcb.com. There are a lot of premade proto boards available but most just have generic rows of holes on 0.1” centers. Installing female headers to connect to the Discovery module would require a good amount of hand wiring on the board. I’ve found a premade proto board, shown in figure 1, that has some pads and routing along the left side of the board which is very nearly what is needed to accommodate the 30 pin right angle female header connector used to connect to Discovery.

BPS-IMG-PR3U.jpg

Figure 1 Pre-made single sided proto board


Figure 2 is a zoomed in view of that section of the underside of the board. In the figure I show the modifications and construction needed to re-purpose this proto board for use with Discovery. First, because the rows of holes are a little too far from the edge to accommodate plugging the Discovery Module into the right angle female header, a notch must be cut into the side of the board as indicated by the green dashed box. The notch extends 6 holes to the right and left of where the right angle connector is installed. Where to install the 30 pin female header is shown by the upper gray box. Zigzag traces on the board connect one row (along top) to another row further down that will be used for one row of the 34 pin vertical female header. The second gray box shows where to install that header. To connect the lower row of 15 pins of the right angle header, a series of short jumpers need to be added while soldering in the headers, as indicated by the orange lines. The solder-less breadboard(s) is then stuck to the top side of the proto board right up next to the vertical header.


Cutting the notch in the side of the board is probably the only potentially messy part of the construction process. You probably should dry fit the right angle connector before soldering it in place to make sure the notch is in the right place and is deep enough.

 

BPS-PR3U_construction.png

Figure 2 Breadboard adapter schematic


I’ve attached a spreadsheet file containing the BOM with Jameco (www.jameco.com) part numbers and prices. The total cost is between $20 and $26. The proto board costs $10.95. A half size 400 connection point solder-less breadboard costs $5.95. The proto board is large enough for 2 breadboards. You could install two or only one and use the rest of the space on the proto-board to build more permanent circuits. Jameco does not stock 30 pin right angle female headers so the BOM lists 2 of the 20 pin headers at $0.99. If you don’t need all 16 digital pins then one 20 pin header will be sufficient, otherwise you would need to cut the second header in half to get the extra 10 pins needed. Or find another source for a 30 pin header. The 34 pin vertical header, at $0.99 each, was chosen because it gives you 4 extra pins for added ground pins or pins for other signals or power supplies. Additional blocks of single row or double row headers can be added around the sides of the solder-less breadboard as needed.

One thing that a breadboard adapter like this needs is extra power supplies. The extra space on the proto board could be used to build positive and negative power supplies using either a wall plug adapter or batteries. The ADP667, +5 V fixed or adjustable Low-Dropout linear voltage regulator (Jameco Part no. 1803518) would be a good choice for a positive supply. The ADM660, CMOS switched-capacitor voltage converter (Jameco Part no. 1802259) would be a good choice to generate a negative supply from a positive supply (such as the ADP667).

As always I welcome comments and suggestions from the user community out there.

Doug

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