In harm's way: ESD vs. transistor gate/base brought outside enclosure

[earthtonesaudio]

So if you brought a transistor's base/gate lead outside the safety of a metal enclosure (through a capacitor, say), what is the risk of damage due to electrostatic discharge (ESD)?

Obviously MOSFETs will bite the dust immediately, but what about JFETs and BJTs?  High voltage/low current spikes, repeated over time, can't be good for the longevity of these things, right?

I don't know where to look for this type of info... perhaps pico-Ammeter manufacturers?


(I'm trying to make a bullet-proof capacitive proximity sensor, this is just one of the many issues I'm trying to sort out.)
Thanks in advance,
Alex

[doitle]

While the pedal was on you could protect it with diodes to ground and to VCC. Once the voltage coming in on the gate/base gets higher than VCC that diode becomes forward biased and latches the node to VCC+Vd where Vd is the diode forward voltage. I don't know if that helps you much but it should protect it at least when the pedal is on.

[R.G.]

See "When good opamps go bad" and "What are all those parts for?" at GEO.

You can make them pretty immune with series resistance to limit current and normally reverse biased diodes to both power supplies and safety ground.

[earthtonesaudio]

That's much easier than I was expecting.  Thanks!