I was called in once by a power supply company that had a conducted emissions EMC problem on a new PSU. I tested one and emissions were some dB's above the limit. I then asked to test the PSU they submitted for testing. It was below the limit. But I then took the lid off and I new straightaway why it had passed. I could hear that it was unstable and this was conveniently spreading the emissions spectrum. I cured the marginal stability problem but had to add an extra filter.
Another example - switching power supplies - sometimes a a faulty SMPSU will emit audible "chirps" or a usually supersonic oscillation will become audible - many's the time I've used that as a diagnostic.
Agreed! Experienced power electronics engineers use all their senses to detect anomalous circuit operation, and hearing is very important. A circuit that is slightly unstable, say, only during a step change in either input or output, often has a distinctive change in noise, in many cases a "chirp", that indicates that some control loops are not quite happy. Back in the days before deep memory scopes I relied on this to detect stability problems. Even today a keen ear can often detect a problem long before someone relying on a scope image.
Off-peak power: here in Australia, one can hear the high-freq signals sent by the power supply authorities to turn off-peak relays on and off. Some times (older) equipment malfunctioned due to this signal, and the best test we had was to plug in a particular soldering iron and just listen for the distinctive "off-peak" sound....
Agreed, by ISO9000, and even good solid logic, measurements must be done by instumentation. But a first cut, fire it up, qualitative run can use all the senses. And when something goes wrong, a good nose or ear is often the first indication. On a power supply, the first indication of a failure is sometimes that loud popping sound, flash of light, and acrid smell. Of course, if that's the case, the fact that the product no longer works makes it obvious.
Evaluating data by sound , smell, or touch is indeed a very good method, particularly when the required results are qualitative, such as "good or bad". But it calls for skilled personal judgement and so it would not be found acceptable by that segment of managers who strongly want to eliminate the need for such skills in the name of uniformity. Think ISO9000 and similar policies.
But listening is still a very handy way to detect problems, beyond any doubt.
Power supply designers use touch all the time to tell if things are running hot. Low voltage circuits, of course. And sight, smell, and hearing give a quick indication that an electrolytic is in backwards. Or, what is left of it was in backwards. If something is hot, we can often tell by the smell if it's a semiconductor or a resistor.
Very much so, I used to deal with multisite modems on a polling system and got to know when there was something wrong on the line by the sounds. For instance, you could teell how many sites were responding, or if one was retransmitting a lot.
While Selinz may be sceptical, just as your eyes will register small changes in what you see, so the ear can distinguish small changes or patterns in modulated data. I can see how that could be used to find patterns or other irregularities in data - it would only give you a starting point for further investigation but you could get through a lot of data quickly.
I used to work in radiopaging sending digital data packets and during development would often say or hear "there was something wrong with that packet". We were rarely, if ever, wrong.
Most people who use(d) modems will have had a "that didn't sound right" moment.
Good comment przemek. And folks still use the AM radio technique. Put it near the AC service panel of a house and see (hear) if any x10, etc. devices are wired somewhere and perhaps therefore interfering with some other system. Turn off individual breakers to isolate and find.
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