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From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: sci.electronics,rec.video
Subject: Re: Soldering in MOSFETs
Message-ID: <548@neoucom.UUCP>
Date: Mon, 13-Apr-87 16:22:21 EST
Article-I.D.: neoucom.548
Posted: Mon Apr 13 16:22:21 1987
Date-Received: Sat, 18-Apr-87 19:24:47 EST
References: <270@lpi.UUCP> <11576@teknowledge-vaxc.ARPA> <1521@umd5.umd.edu>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 38
Summary: Re: wrist strap...
Xref: mnetor sci.electronics:552 rec.video:970


Just a few comments:

1.  Don't ever connect yourself directly to ground by putting a
wire around your wrist and twisitng the opposite end around a
grounded object.  If you came in contact with line voltage by
accident, your execellent ground could prove leathal.  Commercial
straps have large value resistors in series.  Your work area should
also be guarded by a Ground Fault Interrupter (GFI) type circuit
breaker if you are using some sort of device such as the wrist
strap that enhances your danger of electrocution.

2.  Actually, grounding yourself isn't always best. If the item
you are repairing accumulates a static charge, then it can
discharge to gound thorugh you, thus zapping the MOSFET in
question. You might actaually be better off attaching your wrist
strap to the frame of the device that you are servicing.  That way,
both you and the device are at the same potential.  Of course,
there is a slight chance that if there is an initial discharge as
you attach yourself to the device, the induced field in the frame
could zap the MOSFET, but the chances of this are remote.

3.  This reminds me of a story back when I used to work at a
certian gov't. agnecy with a 3-letter name.  They used ao have
everybody wear thier photo IDs etched on a piece of aluminum
hanging from a chain around the neck.  You can imagine what
happened when some guy bent over to tune the output tank circuit of
a transmitter and the ID badge flipped in: yeee-ouch!  They got
smart and switched to polaroid pictures sandwiched in plastic-- but
still on a neck chain.

  --Bill

Bill Mayhew
Division of Basic Medical Sciences
Northeastern Ohio Universities' College of Medicine
Rootstown, OH  44272  USA    phone:  216-325-2511
(wtm@neoucom.UUCP   ...!cbatt!neoucom!wtm)