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Silicone lead for soldering iron -- recommendations?

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Gyro:

--- Quote from: NiHaoMike on September 04, 2020, 01:23:54 pm ---Instead of jumpering across the capacitor, add a 100k-1M resistor in parallel.

--- End quote ---

That's an interesting one. I've often thought that it would be sensible to have some series resistance on an iron tip, in the same way as an ESD strap - if only to stop you taking chunks out of the tip when accidentally attempting to solder something you've forgotten to power off! Also to reduce any low impedance ground loop current spikes.

I know this has been discussed before in relation to soldering irons in general, but I don't remember what consensus was reached (I remember one argument was that you want to know as soon as possible if you're soldering something that's still powered!), however, afaik, all of the (ESD safe) iron manufacturers tie the tip directly to mains ground.

I agree that a parallel RC network including C26 could be a useful solution, the question is sizing. You need to be able to eliminate switching (PWM) noise being coupled from the element to the tip, the 100nF of C26 is hopefully enough to swamp this, however if the R is too high, then there is the possibility of causing insulation breakdown between tip and element, and also of C26, if you accidentally touch a high voltage node (maybe this is a reason that they are normally grounded?), too low a value would smoke the R. Some experimentation of R and C values might yield a good compromise though. I'm just not sure why nobody does it (in general).  :-\

werediver:
My understanding of the reasoning behind grounding soldering iron tips directly (as you, Gyro, have briefly mentioned) is safety: let the circuitry fail quick and safe (by blowing fuses) rather than late and painfully (by electrocuting the operator).

That doesn't help working on powered devices, right, but when safety is concerned, doing so is a no go (perhaps, there are special cases, but then, I'm sure, special protocols and measures are involved).

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