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DIY Greatest Hits.


This is the Synth-diy emailgroup's Greatest Hits page.
Contributions mainly came from the 'danger of 120V mains' and 'biofeedback' threads
and date from the january of the year 1.
Some say there might be bit of a moral to this page, like: Learn from our mistakes.
Ask youself weather you want to be grounded or not. Computer technicians tend to
connect themselves to ground, as it's safer for the chips. But then, if you touch
a charged capacitor in the powersupply, ough!
Keep being aware:
Capacitors are 'stored energy devices' Check them with a meter and see if they
are really discharged!
Otherwise, just enjoy the sparkey blue font.

>> I have been zapped by a tube that was delivered new, in a packing box - it
>>still had a charge after days of storage/transport. The spark came looking
>>for me - a 1/2 inch jump.

>> These days I aligator clip an electricians screwdriver (insulated down as
>> far as the tip) to the earth strap/outer coating of the tube and put that
>> near the opening, or under the rubber cap if present, and let that take the
>> zap. Needless to say, this is done with the mains power disconnected!

Ken Stone
> Isn't it better to put a resistor in series, 1k or so? I think the
> discharge current could be pretty high otherwise.
>
> BTW, I read somewhere people have knocked off the neck of the CRT while
> being zapped...
Ingo Debus
For high voltages like that, unless you like fireworks you probably want
more like 1meg resistor...

At a lab I used to work, we had lines painted on the floor for how far
you'd get thrown by various voltages...  people thought we were weird...

Tom Arnold


>The jibe to Eric was for his Vaccuum tube synths... touching those in just
>about anyplace would be ill-advised and possibly lethal !
Actually I did that a year or two ago.
I was repairing my stereo tube amp.
As it is a weird Philips design (those guys made good but very weird
schematics, and all wired 3D) I was on the phone with a guy who knew the thing
telling me what to measure to find the problem. The amp was open, on (for
measuring I need it on) and connectorwise it could only stand on it's side.
It fell over, towards me. I insictly grabbed the heavy thing with two hands
!WRONG! I dropped the phone. The techy heard me choke.
I got 380 volts DC between my hands!!! (Tube amps not only transform down,
for the glowing coils, but up too, for the kathode guns in the tubes.)
I felt the bass of the music I had on pumping through my arms, I felt my
heart, longs and troat and my swallow pipe cramp heavily. Blood pushed in
my head. I saw nothing but a _very_ bright white light. But I had the
consiousness to let myself fall onto the floor, thus being able to let go
of the amp.
I told the techy what happened, that I felt extremely lucky and stupid, and
that I was going to phone the hospital. They told me to come over fast,but
expected that I was doing OK. Weirdly enough, I went there myself with the
tram. It was only then that the cramps wore off a bit.
When I was in the hospital, I was told not to look at the print coming out
of the heart checker, but to lay still and relaxed. But as I have this
interest in bodyelectrodes, as ya'll know, I did watch it from the corner
of my eye and studied the waves that were printed.
Shortly after, they told me I had a hole in a heartchamber. I said: 'those
are not my heartwaves, I know, I was studying them when they were printed.'
It appeared that the lady in the room next to me had the heart failure.
'Oops!'.
This was a very very odd experience, one onlike anything other, DC is very
other then 220 volts AC I happened to touch lightly a number of occasions,
and very unlike static.
I still feel very lucky and ashamed. I only use one hand when near
potentially dangerous spots, the other is on my back, even when I'm
isolated well. In my job I only use the isolating chair.
I never continued repairing my tube amp.
I guess I have no after effects, apart from knowing what electricity is,
and why you can drive trains on it. It *is* a force. I felt that like
nothing else.

Dave Krooshof


A little survival tip - Back when I was doing theatre lighting we were
always instructed to touch any metal piece of scaffolding with the BACK of
our hands first, since electric shocks tend to cause the muscles of the hand
to contract.  That way you're not grabbing the metal bar and increasing the
duration of the shock.   Also in lighting you tend to be forty feet up on
top of a scaffold when this happens.

Steve Curtin


You Americans have it lucky - you should stick your fingers on 240 V UK
mains a couple of times.
On the few occasions I've done that I've usually found myself inexplicably
at the other side of the room, with any test equipment I was using on the
floor between myself and the workbench, a cold sweat and a pulse rate in the
low audio range...

Colin Fraser


I've been shocked many times by AC over the years. What I didn't "appreciate"
those times was that most of those shocks went only through my fingers (like
when you feel a little buzz across your finger when you plug that lamp in
behind the couch and say, "hey, that doesn't hurt much"). I had a much better
"appreciation" for the (mere) 120V when I came into contact with light switch
(hooked up incorrectly) while standing barefoot on a concrete floor -- a
completely different experience!!! It took me several minutes to even catch
my breath. It's a lot more dangerous when it goes through your heart
(obviously). Better safe than sorry.

John Barlow


> You Americans have it lucky - you should stick your fingers on 240 V UK
> mains a couple of times.
Been there, done that. Then again, I'm not an american.
Got shocked by a faulty 30 year old transformer. Oddly, the reason for the
shock was that my brother who has a license to do electrical
installations, added a grounded power cord to the transformer. I switched
it in, touched the 0V terminal (which turned out to be 220V) and chassis
with my other hand and found myself lying on the other side of the room.
No side effects but the current only passed from arm to arm. Needless to
say, the transformer is staying in the closet. Forever.
Moral of the story: grounds fault protector is not enough necessarily to
protect you AND just because you survive the electricity, it doesn't mean
you won't hit your head on something when you get shocked to the other
side of the room.

Antti Huovilainen


HAH !!!
My best "hits" were...
From a miswired light switch, up the arm, to ground, the top of my bald
head... wet... to a heating duct.  Saw the world turn a lovely purple. Said
"woah!". Did NOT fall off the ladder... Two youngsters in the room said
"what happened dude...?"

From a 1400uF capacitor charged to 350VDC.  Boof. ended up in a chair
across the room, staring blankly. Thinking... should I get help... no maybe
I'll just sit here quietly and wait for my body to settle down.  Cap had 100VDC
left to deliver in case I got stupid again and wanted more...

From a 25KV neon transformer... through a plant stem, the plastic barrel of a
pen... No ground... just capacitive coupling !  Woke up against the wall six
feet away. Decided not to tell the teacher (high school) for fear the experiment
would be terminated immediately.

...
Another major danger (usually forgotten) is arc damage.  Picture the toddler
putting a hairpin, or paper clip, or piece of wire, across the 120VAC.  The arc
could flame spray that metal into unprotected face, start a fire which finishes
the job etc.

Harry Bissell


I recall one of my litany of stupid childhood experiments, removing a plug from
an outlet half way and dropping a laminated piece of C shaped ferrite core I had
pulled from a transformer on top of the two exposed prongs.
Lots of sparks, lots of black marks on the wall, and neat 1 cm long cutouts on
the ferrite piece.

Then there's the time I microwaved Jell-O for 12 minutes and placed the jar on a
cold windowsill. It exploded, I bled a lot. (superheated water experiments are
neat too).

I guess we're all lucky we're not dead.

Vic Vector


You see, both the voltages and the frequencies are pick such that it
will literary burn out the part of the population that would cause
really big troubles later on. This was all done in the spirit of
natural selection and survival of the fitest. Either you know that you
should not do that, or better yeat, not come up with the idea, or you
just plainly survived and got to do it full time.

We in the later category are the selected ones ;)

Magnus Danielson
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