Fullscreen HTML5Med Res (??MB)HTML4

GW-Instek GDS-2104A 100MHz 2GS/s 4-channel digital oscilloscope Review by LEO SIMPSON Digital oscilloscopes continue to become far more powerful and yet cheaper, as illustrated by the release of the GW-Instek range of digital scopes with variable persistence display. Available in 2 and 4-channel versions with bandwidths ranging from 70MHz to 300MHz, they are easy to drive and have a great range of features. O ur review scope was the GW GDS-2104A 4-channel 100MHz model which was fitted with optional plug-ins for a 16-channel logic analyser and a 2-channel function generator, making it a mixed signal (ie, analog & digital) scope with a built-in signal generator which can provide sine, square or triangle waveforms. By the way, GW-Instek will be familiar to many readers, with GW standing for the well-known brandname Goodwill. Features of the scope include a maximum sampling rate of 2GS/second (depending on timebase setting), vertical input range of 1mV/div to 10V/div, timebase range of 1ns/div to 100 seconds/div and a waveform update rate of 80,000/second. It has built-in segmented memory and waveform search options and you have a Zoom window and play/pause to navigate the waveforms. Control via USB is a standard feature while LAN and GPIB are options. Out of the box, the GW scope impresses with its large 8-inch diagonal (160 x 120mm) screen and its well laid out control panel which has all knobs and buttons nicely spaced and clearly labelled. The four BNC probe sockets are not probe-sensing (ie, they don’t sense the probe’s division ratio and alter the vertical sensitivity accordingly) but it 42  Silicon Chip is easy to set the probe division ratio at anywhere between 1X and 1000X in a 1:2:5 sequence with the “Variable” knob once you press one of the channel buttons. Doing so brings up all the relevant input parameters: coupling (AC, DC or GND), Impedance (fixed, in this model), Invert (on or off), Bandwidth (20MHz or unlimited), Expand, Vertical position and Probe voltage. The last of these seven soft-buttons (below the screen), also gives the option of selecting voltage or current as the measured parameter and also allows you to compensate for tiny cable propagation delays in the picosecond or nanosecond range. Incidentally, I should apologise for launching into detailed description of just a few features because that’s how it is with modern digital scopes: pressing a button invariably brings up menus on-screen which you select from with the soft-buttons and then adjust with “Variable” control in the top left-hand corner of the control panel. It is fairly intuitive and if you do become lost, a Help button will give a brief description of the function that you are playing with. As another aside, I must say that I am quite conscious of the scope’s noisy fan in my quiet office as I write this review. This is not generally noticeable in a typical lab or workshop but now that computer fans are generally very quiet, should this one be so audible? One of the best features of this scope is the bright TFT LCD colour screen which has a resolution of 600 x 400 pixels. It gives a good clear display but some people may find the screen fonts a bit small – you will need your glasses in this case. Partly that’s because the designers have crammed in lots of onscreen functions. For example, you can display up to eight measurements from a selection of 36. Then you can add statistics to all those measurements (ie, mean, Min, Max and Standard Deviation). At the same time you get the selection menu down the right-hand side of the screen, vertical and horizontal settings along the bottom screen edge and triggering and date info at the top. With all that displayed simultaneously, less than half the screen is available to show the signals! So lots of info can be shown. You can then remove a lot of it by pressing the “menu off” button. A really good feature of the Goodwill scope is that it has three Demo waveform terminals just below the right-hand corner of the screen. One of these is the standard 1kHz square wave for probe calibration. The second waveform is a pulsed 100kHz square wave and the third is frequencymodulated waveform. These would be very handy for demonstrating how to use the sync funcsiliconchip.com.au tions of the scope as well as just learning your way around it if you have just purchased it. By the way, if you want an output for an external monitor on the rear scope, you need to choose plug-in LAN module option. Besides an ethernet socket, that gives you an SVGA out- put for display on a projector or monitor. Sync functions are very comprehensive, with edge, delayed triggering, pulse width, video, as well as runt pulse, rise & fall and time-out. Mind you, since most video dis- The rear of the GW-Instek scope has two USB ports, one for a printer and the other for control functions via USB. It also has BNC sockets for a Cal output and a Go/No go test function. siliconchip.com.au June 2013  43 plays these days tend to be flat panels rather than CRT-based, most of the video triggering facilities (eg, PAL, NTSC & SECAM) will probably never be used in most cases. Four 100MHz probes are supplied with the scope and they are switchable between x1 & x10. As noted above, you do need to select the probe division ratio which you can do by bringing up the channel input menu, after selecting the relevant Channel Input button. The optional 2-channel function generator, 16-channel Logic Analyser and LAN modules (plugged into the back of the scope) are selected by pushing the front panel “options” button. We had both the Logic Analyser and Function modules installed but the Logic Analyser option is “greyed out”, until the 16-channel connector is plugged into the front panel. The LAN option is similarly “greyed out unless the module is plugged into the back. Incidentally, while the GW scope comes with a very comprehensive instruction 258-page manual on CD, we did not have access at the time of writing for the 16-channel logic analyser or the function generator manuals. The function generator is quite impressive though, able to deliver sine, triangle and square waveforms with the duty cycle of variable and frequency variable from much less than 1Hz to 5MHz and with very fine control available. Want a frequency of 3.567867MHz? Just dial it in as you can precisely set The pockets on the rear panel are there to accommodate two out of a choice of three plug-in module options: the 16-channel, Logic Analyser, the 2-channel Function Generator or the Ethernet & SVGA output module. each decade. Note that you can use the function generator and the logic analyser simultaneously and you can do analysis and decoding of parallel and serial buses such as I2C, SPI and UART (with the module installed, of course). A USB socket on the front panel allows waveforms to be saved in .JPG or .PNG format while a USB socket on the rear panel allows a (Pictbridge) printer to directly print out screen grabs. Overall, we were very impressed with this scope although we only had it for a couple of days – not really enough time to explore all that it can do. Three models are available in the GDS2000A series: GDS2072A, 70MHz 2-channel <at> $895.00; GDS2104A, 100MHz 4-channel <at> $1599.00 and GDS2304A, 300MHz 4-channel unit <at> $2599.00. The optional plug-in modules are the DS2-FGN 2-channel 5MHz Function Generator <at> $229.00; the DS216LA 16-channel Logic Analyser <at> $745.00 and the DS2-LAN, Ethernet and SVGA output <at> $259.00. All prices exclude GST. For further information, contact Tekmark Australia Pty, Ltd. Phone (02) 9911 3888 or 1300 811 355 or see their website at www. tekmark.net.au SC OiTEZ eScope Filter Pro Measurement Function Filter 8 LED Capture Capture USB 2.0 9.0 MegaPixel Camera Polarizing Filter Measurement Software eScope Filter Pro $148.00ea MS1317 The eScope Filter Pro is a new innovative way to discover, capture and share microscopy. Whether in a classroom environment, in industry or for the hobbyist, the eScope has a wide variety of uses from plant and insect identification, to industrial applications. Powerful measurement software will measure many variations of lines, angles and circles. • X & Y Axis Adjustable Stage • 11 LED Translumination • Battery or USB Powered • Easy Lock-in-place Setup • Freely Adjustable • Heavy Base Stand Pen Microscope Stand Pen Microscope 3D Stand $55.00ea $42.60ea MS1316 MS1314 To view over 10,000 products and shop online, visit www.wiltronics.com.au Ph: (03) 5334 2513 | Email: sales<at>wiltronics.com.au 44  Silicon Chip 39 Years Quality Service siliconchip.com.au