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Recently, low-cost pocket oscilloscopes have appeared out of nowhere. While the majority are novelty items, there are a handful that could be useful general-purpose devices that you should maintain in your toolkit. I’ll go over a few of the current options, which are largely designed and made in China but are widely available on eBay. In each example, I include a link to the eBay store as well as a summary of the product’s specifications and characteristics. Except as discussion starters, I don’t necessarily advocate any of these. Many of the high-bandwidth oscilloscopes, on the other hand, appear to be useful. Surprisingly, a larger price does not always imply a higher level of performance. For roughly $100, you can get a very high (relatively speaking!) bandwidth oscilloscope. 

Several of these can also be obtained from other sources. I haven’t interacted with any of these vendors and don’t recommend them. Buyer beware, as with anything acquired on eBay, and take the usual precautions. One scope that will be accessible as a KickStarter project could be worth mentioning. The oscilloscopes are ordered from cheapest to most expensive. This caseless oscilloscope is limited by the fact that it is powered by a USB connection usb oscilloscope. The bandwidth isn’t given, but I’m guessing it’s somewhere between 25 and 50 kHz. With time base options ranging from 100s to 500ms, the sample rate is 250kSa/s. Two DC-coupled inputs with triggered levels up to 5V are available. A 1X tiny probe is included with the unit. Around the perimeter of the PC board are push-button. While the price is low, I would prefer purchasing in one of the other versions.

Please keep in mind that this is a KickStarter project with a deadline of October 28, 2013. The Key-Scope has a 100kHz bandwidth and a 1 MSa/s sample rate, and it acts as a full-featured sensor oscilloscope with a single toggle switch for all functions. The LCD is backlit and color. For measurements, it employs a probe with a ground clip, or you can use an extra 10X probe. The highest input voltage is 42 volts. The waveform can be displayed by connecting the machine to a computer. A good video about the operation can be found on the home page. Key-Scope II and III are two more versions in the final stages of development that will be released later next year. Both convert analog signals at 50/250 MSa/s (max bandwidth 5 MHz/25 MHz, respectively) with an 8-bit resolution. Prices range from $99 to $149. 

The Hantek DSO1022 is powered by a USB 2.0 interface and requires a computer running Windows. With an outside initiating port, there are two 1M inputs. The device boasts a 20MHz bandwidth and a sampling rate of 40MSa/s. Averaging, intensity, and durability settings are all available on the display. Addition, subtraction, multiply, division, FFT, and X-Y plot are all math functions. It also has a built-in signal generator with a fixed 3.3VPP square-wave signal output that can be adjusted from 100 Hz to 50 kHz. The CGM-101 is a 2 different, 200kHz bandwidth, 2MSa/s 11-bit microscope with an auxiliary 200kHz DDS arbitrary power transistor and eight station digital I/O from Circuit Gear. A vector network analyzer is also included, which measures magnitude and phase from 0.2Hz to 200kHz. It runs on USB power and requires a PC or laptop running Linux, Windows, or Mac OS X. The software is free to use. Since 2009, the CGM-101 has been on the market.

A 3.5-inch TFT and a 1000mA super capacitor are included in the QDSO (good for a claimed two hours use). The bandwidth is 40 MHz, which is the highest among these portable DSOs. With a single 1 MOhm input, the sampling rate is stated to be 200 MSa/s. A single 1X probe is included. While the unit is larger than the others in this assessment, it may be helpful for a variety of purposes rather than merely as a conversation piece, as many of the others are