High-Speed Test Instruments: Evolution to Affordability

Everyone, myself included thought that the oscilloscope as an applied test instrument had gone the way of bell bottoms, earth tones and puka shells in the late 1970s. Mostly used to assess secondary ignition systems, scopes were large and heavy - approximately one-fourth the mass of most automobiles at the time, and extremely expensive. With the introduction of electronic fuel injection and direct ignition systems, the need for using high-speed data as a component of diagnosis became obsolete. Or so we thought at the time.

Lest I be misunderstood. When it comes to a versatile and accurate test and measurement device with a very high cool factor, few things match a true analog oscilloscope. But around 1980, most stand-up scopes were placed in a corner to gather dust and were replaced by the digital multimeter (DMM) and later, hand-held scan tools.

Engine management systems at the time were simple and processing was slow, using 8-bit microprocessors and relatively low-speed binary, analog, and linear signals and commands, and the DMM was more than sufficient for the assessment of relevant data.

With the implementation of faster microprocessors and pulse width modulated (PWM) signals and commands, oscilloscopes made a quiet comeback in the early 1990s as stand-alone devices, or as add-ons to more sophisticated scan tools of the day. Not true oscilloscopes, these units were what would be considered very fast graphing multimeters (GMM) with a baud rate of approximately 10,000.

While these early devices were hand-held, they were bulky, slow, and expensive. In addition to these shortfalls, these devices were not very user-friendly by any measure and were not widely or regularly used.

With the adoption of 64-bit processors and ultra-high-speed multiplex communication systems on a broad scale, DMMs were simply not fast enough to capture the data at the rate at which it was being generated. The ability to accurately assess PWM data was no longer a novelty, and a new market emerged for high-speed digital test equipment.

The DMM isn’t going anywhere, and will remain an extremely valuable test instrument for a long time to come. But understandably, advancement in DMM technology has more or less leveled off, as it cannot be improved upon and is insufficient for many of the tasks required on modern systems.

Available GMM options in the mid-1990s through the early 2000s were an improvement, but still left quite a lot to be desired. While smaller and less expensive, these hand-held units were clunky, unstable, difficult to interpret, and had limited capabilities. And at an entry-level price of around $2,000.00, they were still not what many would consider to be readily affordable.

One notable exception was the Fluke 9x/10x series. Fluke has justifiably earned a reputation as the benchmark for scientific test and measurement. While full-featured, accurate and reliable, the only drawback was the expense. With an entry-level price tag of around $5,000, which did not include all of the required accessories, these devices were often out of reach for professional, yet self-financed tech nerds. A used Fluke 96 can now be found on eBay for around $200.00.

UK-based Pico Technologies had introduced a group of extremely refined, Windows-compatible USB interface modules with a mated PC application for high-speed graphing that gained popularity and wide acceptance in the mid-2000s. Full-featured, durable, and fully supported; with self-attenuating input shunts, auto-ranging capabilities, and a wide range of applications that include voltage, amperage, sound, and vibration measurement with virtually unlimited x and y channel ranging and easily adjustable triggers, the Picoscope has become the new benchmark for portable high-speed test instruments.

One can easily invest well into the five-figure range for all that is available from Pico, but an entry-level professional grade Picoscope starts at around $1,600.00. Not prohibitively expensive, but still a bit of a sting in terms of the initial investment.

In the mid-2010s, Chinese precision instrument manufacturer Hantek launched a series of portable oscilloscope/GMM modules that are remarkably good, and inexpensive at the same time. Like the Picoscope, these are also USB-to-Windows devices, and have similar capabilities to the Pico. I have used a variety of different Hantek units for a number of years, and fully endorse the 1008 series, which includes the module, four 40” probe leads, a USB interface cable, and software.

Did I mention inexpensive? About $80.00 will get you started. That’s right. Eighty bucks.

Accessories are similarly inexpensive:

» Voltage attenuator: $10.00 each

» 250cm probe leads: $6.00 each

» 650A amp probe: $50.00

The software takes a little getting used to - especially the upgrade to Windows 10, which must be done manually through the Device Manager, but the capabilities of the device are impressive. Features include eight channels, y-channel range of x1 to x10,000 volts/20 to 1,100 amps, x-channel ranging to 1 nanosecond, fully adjustable triggers, and the ability to record and save data and graphing files. Also included is a feature that Pico doesn’t have: multiple RMS-stabilized digital values that may superimposed onto the graphing field. One would be hard pressed to criticize the versatility of this device, especially for the price.

The 1008 series has recently been updated. The module is now better protected and more durable, but the updated software is a disappointment. The record feature has been removed, and the examples of desired signal graphs are confusing and unnecessary. The price for the second generation unit has also been raised to about $110.00. The good news is that the software for the original 1008 series is fully compatible with the new unit, and is readily available via multiple online sources.

While extremely useful for high-speed binary and analog signals and commands, this device is equally useful for the assessment of binary switching and low-speed linear signal evaluation. Application of the amp probe also provides the capability to perform a relative compression test, which is especially useful for diesel applications.

While support is sacrificed, the Hantek 1008 series is a great piece of equipment. If you don’t like it, you can take it down to the lake to see how big of a splash it makes, and do so with a clear conscience given the nominal monetary investment.