Re: [Phys-L] not political. (FTIR)

[Dan Beeker <debeeker@comcast.net>]

Alas another sea story. I would be very careful putting significant 
reverse polarity on electrolytic capacitors.

Many years ago whilst on submarine patrol I had a ship mate who put 
together a Heath Kit audio amplifier. It was a big one rated at 1000 
Watts. In spite of being a flange head he did a fine job putting it 
together. He'd followed the instructions verbatim and his wiring and 
soldering were exemplary. Unfortunately something was wrong somewhere as 
It would blow the fuse after a few minutes. He asked me to look at it. 
Having had a bad experience with oversized fuses I thought I would just 
start with a visual inspection. So I pulled the cover, powered it up and 
went looking for smoke or indications of overheating.  Having already 
had experience with failing power supplies I stuck my nose in as close 
as I could  and was looking right down on the (really big) power supply 
capacitors. There were two and the both blew at the same time with my 
eyes in too close proximity. All I could see was red. My ship mates 
later told me I looked really strange with the puff ball like material 
from the capacitors all over my eyeballs. Fortunately we had a good 
medic who had just finished a tour in Nam so had seen about everything. 
He washed my eyes out and, even though I had bruising around my eyes and 
looked like I'd been in a bar fight, he declared me fit for duty shortly 
after. Turns out the capacitor terminals had been mismarked. + was - and 
- was +. I now always wear my safety goggles when working inside 
energized equipment. Should have done that from the start.

I don't know how one would know which capacitors were safe to reverse 
voltage and which ones are not safe. Doubt the manufacturer would tell you.

btw I'm interested in titles/sources of both books.

Dan

On 2/23/2023 12:00 PM, phys-l-request@mail.phys-l.org wrote:
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>     1. not political. (FTIR) (bernard cleyet)
>     2. Re: not political. (FTIR) (Sam Sampere)
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> Message: 1
> Date: Wed, 22 Feb 2023 23:19:40 -0800
> From: bernard cleyet <bernard@cleyet.org>
> To: "phys-l@phys-l.org" <phys-l@phys-l.org>
> Cc: David Belanger <daveph@ucsc.edu>, support@vernier.com
> Subject: [Phys-L] not political. (FTIR)
> Message-ID: <B2DB6ED3-C78A-4371-8976-7C20B5EEF7A5@cleyet.org>
> Content-Type: text/plain;	charset=utf-8
>
> Since I was given the UCB physics course lab binder, I've demonstrated FTIR using huge wax prisms and X-band (723 klystrons and 1N21 diodes). Back in the sixties wax was affordable.  Now expanded polystyrene and salt lick blocks are substitutes.
>
> By confusion when ordering a DIY quantum experiment book I received a similar in which the plurality of pp. is making an NMR device.  Since I have the high current P/S and air core coils, I?ll consider making it.
>
> My point:  A few pp. are devoted to barrier transmission using a reversed electrolytic capacitor!!!!  Yup: the Al oxide layer is very thin.  The I-E plot is exponential showing it?s barrier penetration.  One caution:  use the cap. in a box, as it may explode from using a much higher EMF than it?s designed max. reverse EMF.  Exploding electrolytic caps are not pleasant.
>
>
> bc  wonders from where the author found the experiment.
>
>
> p.s.  Haven?t tried it ? after will try automating W/a ramp and Vernier