Enhanced DSO138 Oscilloscope

Oscilloscopes were once expensive and exotic pieces of test equipment (and very good models arguably still are). Today, however, you can get a DSO138 oscilloscope for around $25 from the usual online vendors. While its stated maximum sampling rate is a rather low 1 Msps, and other stats won’t stack up to something costing orders of magnitude more, for what it is it’s a perfectly serviceable low-frequency device.

Creator ROFLhoff wasn’t quite satisfied with the stock DSO138 design, and decided to make a few changes. First off was the addition of a cell phone battery to make it portable. The battery itself was provided via a replacement order some time ago that ended up being two batteries instead of one. Connections were made through an SMD spring connector that matches the battery pads.

As the scope normally requires about 8V for power, converted to several levels, this battery conversion also meant some tinkering to enable it to work efficiently. Notably, this device has a a -5V rail, which was generated via charge pump and an LDO. A TP4056 module was implemented for charging, though at least for now data lines are left out.

To finish the build off, ROFLhoff also made a case for the electronics. The go-to solution would seem to be 3D printing, at the time he didn’t have access to one. Instead he built a box out of perfboard. It’s quite a clever solution, which should keep the device protected in most situations. On the other hand, the exterior holes would easily allow liquid to seep in, so it will definitely need to be kept dry!