IntroductionI usually make a custom PCB for my electronic projects. Throughout development the PCB, however, changes several times. Making a custom PCB at each stage is not practical for several reasons including price, long waiting times between versions and being very wasteful. For all these reasons I use a test board/breadboard/prototype board that can be changed easily and instantly before development reaches a final stage.
|The finished blob is comfortable seated in a test board.|
There is one problem with this approach: test boards are designed to take TTH (through the hole) components and cannot take SMT parts. I usually use SMT parts to make my PCBs as small as possible, so the solution for me so far has been to buy both SMT and TTH versions of a chip, use one for development and the other for the final product. This has been working for me for quite some time, but now I am in a situation where the manufacturer doesn't make TTH version of a particular chip.
|In this case I was using the 8 pin SOIC version of MAX6675.|
SolutionTo overcome this problem I came up with a quick and dirty solution: I solder thin copper wires to each of the pins of the chip and connect them to some pin headers that are soldered in a piece of breadboard. The advantage of this method is that it can be done to almost any chip, doesn't require special resources and creates a very durable design that - so far - seems indestructible. The only disadvantage is that the chip that is "converted" into TTH cannot be used for anything else afterwards. This is not a big problem for me as I always buy more parts than I actually need (just in case I mess up something...).
|A piece of solder-in prototype board|
|Front/Component side of the prototype board|
|Straight type pin header - cut to match the number of pins of the chip|
I also used the following items:
- AWG 35 laminated copper wire
- soldering iron/solder
- hot glue
- sharp knife of saw to cut the breadboard to size
- Pre-solder all the pins of the chip
- Solder about 2-3 cm (1 inch) insulated copper cable to each pin
- Cut a piece of breadboard to size and solder in the required number of pin headers
- Solder each copper wire to its respective pin header
- Important: test and double check if you have soldered everything correctly with a multimeter (check for shorts and breaks everywhere because after the next step it will not be possible to change anything)
- Fill the gap between the chip and the breadboard with hot glue
- When the assembly cools down it's ready for use in a standard breadboard
|All connections soldered and tested|
|Hot glue holds the assembly together - no going back from here!|