An oscilloscope has been on the tool wish list for a while, but good ones are really expensive. But occasionally a simple basic scope would have been better than no scope at all, which is where today’s project comes into the picture.
JYE Tech makes the DSO 138 oscilloscope kit perfect for electronics hobbyists who can make use of a simple scope and also willing to put in the time and effort to assemble one out of a kit. The kit is available at a very low-cost, a fair exchange for making their customers do their own assembly.
This product is popular enough to spawn counterfeit copycats, which was a concern. Not just out of fear of a problematic product, but also the desire to support the original authors. Fortunately JYE Tech offers the option to send in the serial number for authenticity validation. The serial number of this unit purchased from Amazon vendor Kuman checked out as authentic.
There are two versions of the kit that differ by their treatment of surface-mount components: pre-installed or not. This particular example is the variant with surface mount pieces already installed, the customer just has to take care of the remaining through-hole parts. All those parts to be soldered came in a single bag and had to be sorted and identified before assembly could begin.
The instructions were straightforward enough for someone already familiar with basic electronics soldering. The only complaint with this kit is that some of the mount points were not designed for easy soldering. They connect directly to large pieces of copper trace that acted as a huge heat sink making it difficult to bring the solder joint up to temperature. It would have been nice if they etched a little more. Leave one contact sufficient to carry the current, and etched around the rest to serve as a thermal break.
Apart from that minor complaint, the soldering was not difficult, only tedious. The electronics hobbyist is reminded why manual assembly of circuit boards is not considered a great career. This particular example took roughly four hours to assemble. Thankfully, when power was connected, everything started running as they should. Here is the assembled DSO 138, showing the built-in square wave test signal.
A few simple tests followed the self test, clearly showing some limits of this little oscilloscope. For one thing, the voltage scale is quite unreliable. An AA battery at 1.22 volts (according to the Fluke multi meter) was interpreted by this oscilloscope as 1.67 volts. But we didn’t get this thing to read voltages – we want to use it to graph wave forms that we couldn’t see with a multi meter. (UPDATE: On the advice of the local maker who built a DSO 138 before I did, I ran the calibration routine to align Vpos with zero volt and now voltage levels are much closer to the Fluke meter readings.)
It’s now part of the toolbox. Thanks to its low-cost, it wouldn’t take much data to throw it in either of these two buckets:
- Positive: “That was so much easier to diagnose with a scope, even a simple one. This was well worth the money.”
- Negative: “The inaccuracy of the scope led us down the wrong diagnosis path. This was a waste of both time and money.”
While we wait for the verdict to come in, let’s work on an enclosure for this device.