Won without thinking

mark · Apr 17, 2011

Having been out bid on every spot meter I placed a bid on I placed a bid on a Pentax 1/21. Dummy here neglected to notice the 1/21. Due to a lack of available batteries I should not have bid but now my fate is sealed.

Anyone know if this will work as a battery hack but with US pennies?

http://www.flickr.com/photos/eric_duminil/4097107525/

If not then are the lithium replacements any good.

Note to self - stay off ebay

Mainecoonmaniac · Apr 17, 2011

Great illustration! I have an old Minolta SRT with no batteries. I use a hand held meter

CGW · Apr 17, 2011

Between APUG and photo.net, there's a trove of info on hacks and workarounds for merc battery replacements. At least the 9v won't be hard to replace!

JOSarff · Apr 17, 2011

There is a chain of stores called Batteries Plus and they have batteries from watch to car sizes. Try them. Failing that, try ebay again, that's where I got the adapter for my Pentax 1/21.

Joe

2F/2F · Apr 17, 2011

D'oh! Let us know how you get that worked out. I really like those meters, but the battery issue is a pain.

paul_c5x4 · Apr 17, 2011

PX640 adaptors are available - In the UK, try: smallbattery.company.org.uk

mark · Apr 17, 2011

Shipping $ from the UK would suck though. Been looking and there are places here in the states who say they make just such an adapter at roughly the same cost (factoring currency cost) but Something about the sites say not trustworthy. Can't put my finger on why, I just got "the feeling".

Matthew Rusbarsky · Apr 22, 2011

I've been going crazy trying to cobble together springs and spacers for my TL-Electro. That penny stack is inspired genius!

John Kasaian · Apr 22, 2011

You might try Quality LightMetric in Holywood,CA to see if they can convert it to take common batteries & calibrate

pbromaghin · Apr 22, 2011

Those are Euro-pennies. Would they conduct the same as American?

dhosten · Apr 22, 2011

Shipping from the UK is not bad, I buy from the auction site there often, and Royal Mail Small Packet is usually 2-3 pound, so less then $5.00 US . Might be worth it if it is hard to find.
fwiw I was selling my own 1/21 Honeywell Pentax Spotmeter and realized the battery issue after the auction ended. I communicated with the buyer and told him it was no good without the adapter, and we electronically shook hands and walked away. My cost was about $10 for the auction seller fees, but its worth it to keep a good auction rep. I'm mostly a buyer there and a sometime seller.

k_jupiter · Apr 23, 2011

Gossen makes an adapter. It works. Price has gone up since I did mine about 8 or 9 years ago.

http://www.bhphotovideo.com/c/product/89868-REG/Gossen_GO4145_Adapter_Kit_Battery_Holder_for.html

tim in san jose

spark · Apr 23, 2011

Any metal coins that fit will work. Remember that the current drain of a meter is very small so the voltage drop differences due to different metals will be tiny as well. The original battery cases and straps in the cameras are steel, not a really great conductor, so it's not necessary to worry much. My TL-Electro is very happy with a 3-volt Duracell 1/3N and a short #6 nut and bolt all placed in some tubing.

Diapositivo · Apr 23, 2011

A good repairer should be able to make a small voltage regulator circuit inside your device (camera, or exposure meter) if there is space. That would be the definitive solution, it should cost you some tenths of dollars.

Any other solution can be quite acceptable but, as far as I understand, it is not perfect as typically a device having a mercury battery does not have a voltage regulator circuit inside. Even with adapters, the voltage of silver batteries, and even more of alkaline batteries, is not stable throughout the battery life, so the results of the light meter might be slightly off.

Generally speaking, if you only use negatives, you can disregard any small imprecision. And if you need good precision, a separate light meter might be better. But if for whatever reason you want to put your camera to its best possible state of performance, then the best thing is to insert a voltage regulator inside, after which also cheap alkaline batteries will be fine.

This is what I gathered so far but I'm not an expert in electronics so any rectification is solicited and welcome.

Fabrizio

Matthew Rusbarsky · Apr 23, 2011

pbromaghin said:
Those are Euro-pennies. Would they conduct the same as American?

No idea. Please did between the cushions of a European couch and report back.

k_jupiter · Apr 24, 2011

Diapositivo said:
A good repairer should be able to make a small voltage regulator circuit inside your device (camera, or exposure meter) if there is space. That would be the definitive solution, it should cost you some tenths of dollars.

Any other solution can be quite acceptable but, as far as I understand, it is not perfect as typically a device having a mercury battery does not have a voltage regulator circuit inside. Even with adapters, the voltage of silver batteries, and even more of alkaline batteries, is not stable throughout the battery life, so the results of the light meter might be slightly off.

Generally speaking, if you only use negatives, you can disregard any small imprecision. And if you need good precision, a separate light meter might be better. But if for whatever reason you want to put your camera to its best possible state of performance, then the best thing is to insert a voltage regulator inside, after which also cheap alkaline batteries will be fine.

This is what I gathered so far but I'm not an expert in electronics so any rectification is solicited and welcome.

Fabrizio

A good repairer will tell you to pay the 40 bucks and do it correctly.
Silver oxide batteries do have different use curves, so replace them more often. They fortunately are cheap in most parts of the civilized world so this should not be an inconvenience.

The difference in voltage between Mercury and Silver oxide batteries is enough to screw up even negative film. If you just want an idea, sunny 16 works better than the wrong data given by a light meter. Personally, I like my equipment to work the way it's suppose to.

Developing negatives has enough variables to control that adding one more (What camera did I shoot this in?) doesn't seem like a great idea.

tim in san jose

alanrockwood · Apr 24, 2011

pbromaghin said:
Those are Euro-pennies. Would they conduct the same as American?

Not these days, what with the exchange rate of the dollar down with respect to the Euro.

(Sorry, couldn't resist the comment.)

pbromaghin · Apr 27, 2011

alanrockwood said:
Not these days, what with the exchange rate of the dollar down with respect to the Euro.

(Sorry, couldn't resist the comment.)

Do they look funny when they throw a ball?

Sethasaurus · May 1, 2011

Let me see..
2 of the old PX640 would give you 2.7V. 2 of the ZA675 will give you 2.8V. So you're about 3.5% over-voltage - shouldnt be too much of an error, should it?

6 euro cents plus 82c standard post = 88c
Send me 88 euro cents via Paypal and I'll post you 6 shiny euro cent coins

kwall · May 1, 2011

Would these work?

k_jupiter · May 2, 2011

kwall said:
Would these work?

Define 'Work'.
They will fit. But... they are still a 1.5 volt battery. Mercury batteries were 1.35 volts. If you don't mind your meter being off 9 percent or so, they will work fine.

Get the adapter and sleep well, knowing you are in the ballpark with your meter readings.

tim in san jose

mark · May 2, 2011

K. Jupiter's idea while good is on back order with a 1-2 month wait from what I can tell.

Anyone know if this will work or dealt with this guy? need an engineer's opinion
http://www.buhla.de/Foto/batt-adapt-US.pdf

Sethasaurus · May 2, 2011

Actually, I was serious and don't mind sending a few euro cents in the post. They're 16.25mm diameter.
I think the smallest US coin is the dime which is too big.

There's more than one way to skin a cat.

Washers are another option. You won't be able to measure any voltage drop across a penny or washer.
One thing to remember is the zinc-air cells need air..

http://www.buhla.de/Foto/batt-adapt-US.pdf

He's got it right. You could use silver oxide cells and drop the voltage with diodes. Depending on the diode, you'll be very close, voltage-wise.

Try this: washer - plastic sleeve - washer.
Where the plastic sleeve contains a 1N4148 (or two schottky diodes) in series with the washers.
|---|>|--|>|---|

Does anyone need to pay $39.95 (or nearly £40)for an adapter?... (and you'd need two..)

k_jupiter · May 2, 2011

Sethasaurus said:
Does anyone need to pay $39.95 (or nearly £40)for an adapter?...

Only if you want your mercury battery designed equipment to work correctly.

tim in san jose

Sethasaurus · May 2, 2011

Oops, I keep imagining the camera which used two cells, but you're talking about the spotmeter, which only uses one. So, one schottky diode of the correct type would work (or one of the expensive adapters).

Won without thinking

Privacy & Transparency

Privacy & Transparency