[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Dec 18 10:20:55 EST 2015

In message <CANX10hB-OCaLKkjE8YENQZpnHxmvx3pxZpsjqvKQ0AeJdqWytA at mail.gmail.com>, "Dr. David Kirkby (Kirkby Microwave
 Ltd)" writes:

I belive in the instant case Lead-Acid was used as a noise-free power
source rather than as backup.

>If do, I believe that the choice of a lead acid battery is a poor one.  I
>believe that even the sealed ones release very small amounts of sulphuric
>acid [...]

Lead-acids, sealed or not, shall always be ventilated.

The main problem is actually not sulphuric acid but rather hydrogen.

Apart from the potential to explode if it accumulates, hydrogen is
bad for pretty much all metals, which it penetrates easily.

(The way one filters hydrogen is to pump it through a filter consisting
of a 2mm thick massive slab of Rhodium, and it isn't particularly hard.)

>That said I somewhere read they were banned in Europe [...]

Anything involving Cadmium is banned under ROHS and for good reasons.

You can still get approval to use them in specialized applications
where there are no realistic choice, provided you make provisions
for their safe recycling.  Few such approvals have been given.

A lot of the stuff which says "NiCd" these days is actually
Nickel-metalhydride where the marketing department hasn't got the

>I don't know if there is any simple way of slowly charging Lithium Metal
>Hydride batteries.

There isn't.  They're almost the worst possible kind of battery for

Lead-acid is still the best way to go.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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