Mercury Battery Equivalent???

[lovestheshow]

I just got ahold of a 1975 Super 8...the problem is I don't have an electric-eye battery. Is there any way to get past this obstacle without trying to find an old mercury battery in another country?

[BolexPlusx]

If the battery in question happens to be a PX-13 cell, you may be in tremendous luck. I was in a local drug store recently and they had a Zinc Air replacement that is almost the exact voltage of the original mercury cell.

Now, this isn't the perfect replacement, they only last a couple of weeks after you activate them by removing the seal. However, at a little over a dollar per cell, and right off the shelf in a local store, they are not a huge investment in a camera that may or may not work. Once you know that it does work, then you can go for the fancier, higher cost, lower maintenance replacements, or just buy the 8 pack for $8.99 and change them frequently.

But before we go too far, what cell is it?

(Enjoy your camera!)

[lovestheshow]

Unfortunately it's a px-14...I read somewhere that it might be possible to use two varta 675s but that it hadn't been tested. If i found a 2.7 volt battery and some how hooked it up using connecting wires, would it work? Or does it have to be a certain type of battery?

[BolexPlusx]

I know the PX-14 very well. It's actually two PX-13s inside a case connected in series.

When I started to get back into filmmaking again I sought out the GAF ST/602, partially because it is a pretty nice all metal camera with some great features, partially because my long dead first movie camera was one of these, and maybe I'm a little sentimental.

Well I got one and it uses this battery. I found an Alkaline equivalent replacement cell on this website:

http://www.photobattery.com/

It is in there under A14PX for $6.00. You might want to try asking at Radio Shack too but I'll give you odds these people will get it to you faster and save you two trips to get it.

The warning here is that instead of the exact 2.7V, this replacement is 3V. I'm kind of hoping that since my camera has an exposure adjustment I can fine tune it to cancel out any effect of the extra voltage. I keep meaning to take the camera to work so I can hook it to a lab supply and wiggle the voltage up and down and watch what the meter does, I just never get around to doing it.

I've heard of people dissecting the PX-14 casing and replacing the dead PX-13s inside. I've never been able to make this work reliably (What a waste that engineering degree turned out to be!)

Along similar lines, if somehow you connected 2.7V in at the right polarity (careful!, the plus and minus of this battery are not what the shape suggests they should be!), absolutely it would work. The question is how robust is it going to be under actual usage. However, it's a smart thing to do just to test the camera before you go too crazy trying to replace the cell.

<font color="#a62a2a" size="1">[ August 17, 2002 10:22 PM: Message edited by: BolexPlusx ]</font>

[BolexPlusx]

Just as a follow up here.

I brought the camera to work today and set it up with a variable power supply in place of the meter cell and pointed it at a light source. I measured the "3.0V" alkaline cell at 3.1V with a calibrated digital voltmeter. I then swung the power supply voltage from 2.7 to 3.1V and the needle of the light meter rose from f3.8 up to f5! I then used the camera's automatic exposure sensitivity adjustment to bring the needle back down to f3.8. I then stuck the alkaline cell back in the camera and the needle was still at f3.8.

How linear this is going to be over the entire range of light levels I don't know. Happily, when I got home I stood out in the yard with the camera in light levels typical of the ambient I want to use this camera in and I was in the high f3 low f4 neighborhood. So at least in that range I should be OK.

The proof is in the pudding though, now I need to shoot some film and let the results speak for themselves.