原创 Device stacking

Do you still remember the Heathkit "Stackables"? These were presented with a blue plastic box and a white front panel in build-it-yourself kit form.

As I recall, the Ix-528x series included a multimeter, RF signal generator, audio signal generator, signal tracer, RLC bridge, and -- possibly (I can't remember for sure) -- a power supply. These were a family of low-cost basic test instruments for the electronics experimenter/hobbyist/repair person. Their notable claim to fame was that they were all built into the same plastic cabinet that featured molded feet that interlocked with a molded top ridge so they could be stacked vertically and stably on a benchtop, thus saving a lot of scarce and valuable real-estate.

Think for just a moment about this simple concept, and how it can similarly apply in your food pantry. Lately I've noticed two types of tin cans -- the older style that can be vertically stacked because their bottoms mate with the tops of the cans beneath them (e.g., Campbell's soup tins), and a newer style that was designed by some dimwit who did not think to include the stackability feature (e.g., Kroger-brand veggies). Try to stack these types and they come crashing down like a house of cards. No question as to the preferred type to make the best use of the limited horizontal space in a pantry.

Other than the intentional Heathkit stackable feature, most older styles of test equipment were not designed to be stackable. However, since they typically came in flat-topped cabinet enclosures, this was an inherent attribute. Even units from different manufactures could easily be stacked on a bench into a reasonably stable "tower of power" -- just look at any of illustrator Daniel Guidera's monthly EETimes caption contest cartoons for examples.

Then, along came the aesthetic enclosure designers hired by marketeering managers with no brains. Fancy curves and non-flat tops -- test equipment styling started looking more like sports cars than truly functional items. The result is that many of them can no longer be stacked.

Keeping this in mind, let's look at how some of these non-mating test equipment boxes can be made to fit together on a limited-space benchtop. Consider the DMM sitting on top of a power supply as shown below. The unfolded front tilt-flap of the DMM keeps it from sliding backwards off the tilted-upwards power supply, but it tends to slip forward and hide the power supply's display.

 

However, when the tilt-flap folded against the DMM bottom as shown below, it prevents the DMM feet from engaging the power supply and it slides off.

 

One solution is to forcibly remove the annoying tilt-flap from the DMM, thereby allowing its feet to hold it somewhat in place. But the serial number that is on the tilt-flap is no longer part of the DMM, which could raise some issues with the ISO-9000 calibration auditor.

Next, consider the frequency counter sitting on top of a function generator as shown below. The front lip of the frequency counter holds it from slipping off the function generator, but it does make the function generator's button labels hard to see.

 

Swapping these two devices round and placing the function generator on top of the frequency counter doesn't work; the function generator's tilt-riser holds it from slipping off, but hides the counter's digits.

Even identical equipment made by the same dimwit manufacturer who never considered stackability can be stacked with the aid of series-connected cable tie-wraps as shown below (don't use duct tape because it can cover up the ventilation holes). By the way, if you have to tie-wrap-stack two scopes together to make a 4-channel scope, you (or your corporate fiscal expenditure manager) might be a Redneck (with apologies to Jeff Foxworthy).

 

Note that these Atten brand "Scopes from Hell" have a couple of functional bugs (among many) that are clearly visible in the above photo. One of these bugs is fairly obvious -- the other is a little more hidden. Can you spot these bugs? If so, please post a comment below. Also, please offer any suggestions you have for stacking these types of devices on your benchtop.

Glen Chenier

Engineer