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Mercury PX625 and PX13 replacement batteries!!
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PostPosted: Thu Apr 05, 2007 1:18 pm    Post subject: Mercury PX625 and PX13 replacement batteries!! Reply with quote
Well, I finally found replacements for the Mallory PX625 mercury oxide battery (and the PX13 equivalent)!!

Click here to see on Ebay

I have loads of stuff that uses it, from my old Gossen light meter to a bunch of Praktica cameras, and now the Canonet.

So here's the link, the guy is selling them at good price, only make sure you ask him to modify the invoice with the Intl shipping price if you buy from outside the US, he sends an invoice which is correct for US buyers only, I clicked on the pay button and then got an angry email in which he said he shipped the batteries but complained about me paying the wrong price.
Of course I replied him that he must take care to make the invoice editable with the international shipping options, I sincerely did not even notice about it, because I am used that all the other US sellers always give me the correct invoice.
Anyway I sent him the further 1US$ needed with a second paypal payment.


PostPosted: Thu Apr 05, 2007 5:33 pm    Post subject: Re: Mercury PX625 and PX13 replacement batteries!! Reply with quote
Orio wrote:
Well, I finally found replacements for the Mallory PX625 mercury oxide battery (and the PX13 equivalent)!!

Click here to see on Ebay

I have loads of stuff that uses it, from my old Gossen light meter to a bunch of Praktica cameras, and now the Canonet.


Those Wein cell batteries are rather expensive and of limited utility. After you have activated one, it will go flat in a few months whether you actually use it or not - they are not like the mercury batteries which last "for ever". In addition you must make certain that the battery compartment of the light meter or camera isn't airtight as the battery needs air in order to work. A much cheaper alternative is to use similar air-zinc hearing aid batteries which you can buy in six/eight packs from many supermarkets. They are not quite as good and have the same weaknesses, but they will cost you less than a quarter of the Wein cells. However, I use silver oxide batteries in my Gossen Lunasix in series with a small silicon diode which drops the voltage to almost the correct level - this setup is almost as good as the original mercury battery and very much cheaper to use than any zinc-air battery. Any instrument which required two mercury batteries can easily be converted to use silver oxide batteries - the necessary silicon diode costs about ten cents.

Veijo


PostPosted: Thu Apr 05, 2007 6:05 pm    Post subject: Re: Mercury PX625 and PX13 replacement batteries!! Reply with quote
vilva wrote:
However, I use silver oxide batteries in my Gossen Lunasix in series with a small silicon diode which drops the voltage to almost the correct level - this setup is almost as good as the original mercury battery and very much cheaper to use than any zinc-air battery. Any instrument which required two mercury batteries can easily be converted to use silver oxide batteries - the necessary silicon diode costs about ten cents.
Veijo


Thanks Veijo.
Is there a link with an explanation of the assembly and the exact type of diode to buy?


PostPosted: Fri Apr 06, 2007 7:34 am    Post subject: Re: Mercury PX625 and PX13 replacement batteries!! Reply with quote
Orio wrote:
vilva wrote:
However, I use silver oxide batteries in my Gossen Lunasix in series with a small silicon diode which drops the voltage to almost the correct level - this setup is almost as good as the original mercury battery and very much cheaper to use than any zinc-air battery. Any instrument which required two mercury batteries can easily be converted to use silver oxide batteries - the necessary silicon diode costs about ten cents.
Veijo


Is there a link with an explanation of the assembly and the exact type of diode to buy?


Well, I don't have a link. I saw an explanation of the principle somewhere and having done a lot of electronics tinkering just applied it. You need a physically very small diode so that it will fit in the battery compartment in addition to the silver oxide batteries which are smaller than the original mercury batteries, e.g. a 1N4148.

Basically, you only need to turn the wires of the diode into small enough spirals to fit inside the compartment and isolate the two spirals from each other with a suitably thick layer of some non-conducting material, even masking tape will do, a couple of millimeters worth so that the upper battery will make contact with the compartment cover. Just take care that spiral facing the batteries doesn't short the battery. In the Gossen, the arrangement is, from top to bottom, as follows: the compartment cover - the plus end of the battery stack facing the cover - the diode with the end marked with a black (or white ) ring touching the minus end of the batteries - the other end of the diode against the bottom of the compartment.

At first I used just tape, but then I found a protective cap for the older type of PC keyboard connectors (larger than the present PS/2), which had a suitable inner diameter to house the batteries and could be cut to fit the battery compartment. The plastic is rather soft, and it was easy to make a slot for the diode with a sharp knife, like this:



There was a larger diameter rim which also had to be removed. You can, of course, use any suitable piece of plastic tubing, and a small coin will do as a vertical filling at the bottom - just use your imagination.

Veijo


PostPosted: Fri Apr 06, 2007 7:57 am    Post subject: Reply with quote
Thank you Veijo. You're not only a lens connaisseur, but also a master of the DIY!
(not to mention the very kind and helpful person!)


PostPosted: Thu Mar 25, 2010 4:35 pm    Post subject: Reply with quote
I know that this tread get his second birthday soon, but I've found a solution for this problem - a little bit expensive, but working.
http://www.smallbattery.company.org.uk/sbc_mr9_adapter.htm[/url]
Perhaps it can help anyone.


PostPosted: Tue Dec 16, 2014 1:13 pm    Post subject: Reply with quote
The diode when it is crossed by a continuous current is equivalent to a resistance in series, and a voltage generator.
The - of the diode is the horizontal bar ... is upside down compared the two batteries.
The two batteries in series give a voltage of 3 Volt.
From 3 volt we must subtract 0.3 Volt of the diode (because is equivalent to a voltage generator not in series to the batteries)




I am an electronics technician (ITIS PARMA)



another solution is to solder the diode inside the gossen

http://www.biasedlogic.com/index.php/calibrating-gossen-lunasix-3-lunapro/

http://gbchcf.free.fr/lunasix3.htm


PostPosted: Tue Dec 16, 2014 4:32 pm    Post subject: Reply with quote
Today I went to the electronics store (ITALCOM)
the seller advised me to use a 1n5819 (Schottky diode)
i have a working Gossen Lunasix 3 with two 357 batteries


PostPosted: Tue Dec 23, 2014 10:02 am    Post subject: Reply with quote
http://www.learningaboutelectronics.com/Articles/Schottky-diode.php
0.4V..but the voltage of 357 is 1.55V
Laughing Laughing Laughing
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