As you may or may not know, my BSc degree is in Control Engineering. I think they call this Systems Engineering these days. The idea is to have a mix of math, electronics, mechanics, and fluidics — “One engineer to rule them all,” as it were.
We learned a lot of “stuff” at university, including the problems that can arise from electrostatic discharge (ESD). As it says on the Wikipedia:
Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. A buildup of static electricity can be caused by tribocharging or by electrostatic induction. The ESD occurs when differently-charged objects are brought close together or when the dielectric between them breaks down, often creating a visible spark. ESD can create spectacular electric sparks (lightning, with the accompanying sound of thunder, is a large-scale ESD event), but also less dramatic forms which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices.
Later, when I started working, all of the engineering stations were equipped with electrostatic mats and armbands, and it became second nature to strap on one’s armband before reaching for a tool or touching a component.
The problem about something becoming “second nature” is that you eventually stop thinking about it consciously, which can lead you into trouble if you aren’t careful. Take my Prognostication Engine (ask no questions) for example. This bodacious beauty has been years in the making. The main portion of the engine is housed in a 1929 wooden radio cabinet.
Sad to relate, there wasn’t enough room in the cabinet for everything I wanted to implement, so one of my chums — Master Carpenter Bob Lokey — handcrafted the smaller cabinet on top, right down to the hand-carved rosettes. Bob did a phenomenal job; so much so, in fact, that everyone assumes the combined cabinet came this way.
As you can see, the main control panel is festooned with antique toggle switches and pushbutton switches and potentiometers (actually, only the knobs are antique, the pots themselves are modern and motorized, but that’s a story for another day). Each of the switches and pushbuttons are equipped with two tricolor LEDs, while each knob is accompanied by a ring of 16 tricolor LEDs.
The relevant part of this machine to us here is the “furnace” on the right-hand-side of the upper cabinet’s control panel. This is, of course, illuminated by tricolor LEDs (the antique copper-and-brass fire extinguisher mounted on the side is just for show). Observe the inverted brass cone sticking out of the right-hand side of the upper cabinet. In order to power-up the engine, the user first holds a flame under this cone (I personally use a gas barbecue lighter).
There is a temperature sensor mounted at the other end of the brass pipe. After a few seconds, you hear a “pop” as the furnace “ignites” and starts to flicker. At this point you work a 100-year old leather foot pump (not shown above) that was originally used by a dentist to power his drill. If you pump hard enough, the furnace gradually starts to glow brighter and brighter. When the time is right, you throw the knife switch and — if you are lucky — the engine will commence its main power up sequence, but we digress…
Sad to relate, I must admit that over the years I had grown to be a little blasé with regard to utilizing ESD protection whilst working on my hobby projects. Observe the image below, which shows the Prognostication Engine’s furnace under construction.
On the left we see the case from a defunct analog meter. This holds a piece of card carrying 64 tricolor LEDs. The disk of what appears to be frosted glass to the upper-right of the case is composed of crushed glass mixed with clear epoxy. This acts as a diffuser and reflects and refracts the light from the LEDs. The disk of rippled glass mounts in the front of the case. When combined with appropriate LED sequencing, this all goes to give a realistic sense of flickering flames.
Sad to relate, I had been thinking of the furnace as a sealed unit that I would never have to service (more fool me), so I used dabs of epoxy to secure the various elements in place.
When I first powered everything up, even with a rudimentary random effect, the furnace looked awesome. So much so that I immediately scampered through the building to the next bay to ask my chum Ivan to come look. After Ivan had said “Ooh” and “Ahh” and departed, I started to wonder if the 64 LEDs were heating their metal container, so I reached behind the cabinet to have a feel.
Zap! The furnace died. I’d been bitten by ESD. I’d obviously built up a static charge walking on the carpet as I meandered back and forth between bays. “Oh dear,” I said to myself (or words to that effect). It was around this time I remembered that I had used epoxy to mount everything inside the furnace (that’s a mistake I won’t make again).
Suffice it to say that I am once again scrupulous with regard to my ESD regime. I have an ESD mat covering my home workbench (which my wife foolishly considers to be our kitchen table) along with an associated ESD wrist strap. I also have an ESD mat and wrist strap here in my office on the off-chance I need to handle any electronic components or dabble with the Prognostication Engine.
How about you? Do you have any ESD-related stories you’d care to share?