SMD Soldering Practice: Basic FM Receiver

A few days ago, I received a 5Watter kit from Diz, W8DIZ. I knew that it would contain some small parts but they were even smaller than I imagined.

In preparation for soldering smaller and smaller components, I decided that a lower cost kit would offer the practice necessary to solder these small parts. While there’s lots of boards that offer solder practice, I wanted to find one that I would get some use out of and offer the soldering challenge I needed to progress in my kit building. This FM broadcast receiver kit was just the thing.

There weren’t many parts, only one SMD IC component, and no real instructions, but it only cost $5 from eBay.

To my surprise and relief, soldering the SMD chip to the board was really easy. I am glad that I had some desoldering braid on hand in order to eliminate the bridges between leads. In total, it took ten minutes tops to tape the component in place, solder the leads, desolder the bridged leads, then inspect my work with a jeweler’s loupe. It is worth mentioning that my soldering iron has a tip that isn’t the largest but isn’t needle thin either.

From there, it was a routine soldering project. The schematic was on the eBay page and there were only two components that I needed to differentiate. All the resistors had the same value, as did the electrolytic caps. There were only two different values of ceramic caps to put in the correct places, so I went over to the computer, looked up the schematic, took a few notes, then went back to work.

In order to not get in my own way while installing components, I soldered my way from the inside out. It was quick, easy, and enjoyable work.

Before I soldered the AA holster to the board, I got curious. I wondered if I could use one 18650 instead of two AA batteries. As I was poking around for a data sheet, I found the original instructions for the kit. It specifies a voltage of 3.3VDC, which is just over the voltage of two new AAs. A fully charged 18650 is around 4.2VDC and I was afraid of killing the circuit so I decided to use the AAs that the kit specifies.

This project was highly satisfying. Not only did it build my confidence in soldering smaller SMD ICs but also provided an enjoyable listening experience. The audio quality is astounding and even more so considering it comes in such a small package. With this SMD soldering experience under my belt, I’m looking forward to building the 5Watter even more.

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