Tried this MR9 adapter (PX-625 to silver oxide) from Thailand?

[john neal]

Gentlemen,

As a one-time manufacturer of adapters (until the EU told me I had to stop using lead based solder), I would caution against using the Cris adapter in high current applications, such as Nikon F or lightmeters - the current required is far too high for the electronics in the adapter. The Cris is designed for currents in the micro-amp range, while meters will pull milli-amps (i.e. a factor of 10 greater) - it will seem to work, but you could easily get what is termed "folding" where the device just gives up due to heating of the diode, which temporarily fails, but then comes back for a while as it cools - and so on.

I believe that the 2-cell adapter for the Gossen, etc uses a correctly specified diode, so should not present any problems.

The diode I used was capable of carrying up to 2A, provided that adequate cooling was available, so a photographic application that required even 500 milli-amps was never an issue. If you check the Cris specification, I think you will find it comes up short of that by some margin (max 200 micro-amp) so it won't even work correctly in a Canonet, which seems to be the most popular use for the device! Nothing against the Cris device - use it for low current applications, and it is fine.

For any of these adapters, you should use a silver-oxide battery (SR44) or equivalent, in order to get the correct output voltage from the device. If you use an alkaline equivalent, the voltage while the cell is new will be OK, but the decay curve is much steeper, and you will end up under voltage rather more quickly than you expect. The decay curve of the SR44 is much more like the old mercury cells - quite flat until the cell is exhausted.

 

[Rob-F]

Well, I'll see what happens. The instruction manual says M5 meter has a very low drain current on the battery, so that you don't have to worry if it remains on when not in use. So for the M5, at least, maybe it's not a problem.

 

[john neal]

Rob,

M5 should be OK - it is a low current device. You might expect a whole year between battery changes, depending on use, the quality of the battery, temperature, etc.

 

[Cold]

So as someone who's intimately familiar with the physics involved in the situation, what would you recommend for the average Canonet owner looking for an adapter?

 

[sevo]

while meters will pull milli-amps

Which one does? My FTn meters seem to stay in the sub-mA range. Ok, AE cameras and cameras with electronic displays pull more. But most plain old match needle CdS camera are very low current devices at least unless pointed at a very bright light - many did not even have a off switch, their battery consumption inside the average camera bag being negligibly small.

 

[rfaspen]

Rob-F, I'm sorry I didn't read this in time to share my experience with the pratedthai adapters and help you avoid a purchase. When I received my duds, I attempted to share my problem with pratedthai to see if something could be done to remedy the situation -- silence. I wasn't out too much money, but after waiting for so long (a month) for the adapters to arrive and wanting to use my CL and light meter for so long, it was frustrating and disappointing to receive junk. I view the pratedthai adapters as either a scam, or incompetence and apathy at best. So maybe you'll get lucky and receive working adapters....but if you don't, I wouldn't expect any recourse with pratedthai.

Now, the adapters sure look pretty. I'm not sure why they don't work. I haven't taken the time to take one apart and see if there is a diode in there and it was just assembled shoddily, or if its just an empty but pretty shell.

I'm quite sure the CRIS adapter is not the same as the pratedthai adapter. I mean, they're not produced by the same entity. Of course, they're both supposed to do the same thing.
I found that the guy in Netherlands (can't remember his name now) makes nice adapters at a reasonable price. At least they work in the CL and Gossen light meters. He also sells kits if you want to assemble your own (you'll need to get an alkaline PX625 and drill it out; not for everyone). I'm confident the Gossen double adapter works, but its quite expensive if you can even find one (I've tried).

Also, as people have said in this thread, only use silver oxide cells in the adapters (working adapters, that is). Those will provide the closest performance to the old mercury batteries possible today. They also have less tendency to leak and corrode.

 

[sevo]

I found that the guy in Netherlands (can't remember his name now) makes nice adapters at a reasonable price.

That would be Frans de Gruijter. If you want to power some camera known to go through batteries at an alarming rate, his might be the way to go, as they use a regular diode and none of the SMD mounts as on those other adapters. But in general, the choice of adapters is less critical than this thread might suggest (as long as you avoid scams). I own a DIY one made to FdG's instructions, three Criscams, and a pair of Japanese Kanto ones (which the Thai ones supposedly are clones of) - all of them do drop the voltage as supposed, and have never failed in my 675-dependent cameras (essentially F FTn, Canon F1, Oly 35RC, plus some more that only rarely see use and a battery).

 

[Solinar]

I use the Kanto variant of the MR-9 battery adapter in my Olympus 35RC.

My advice to everyone is to check the operation of the MR-9 adapter with a hand-held meter set in its reflective mode against your camera's meter readings in a variety of light. It's an easy check.

Best Regards,

 

[john neal]

So as someone who's intimately familiar with the physics involved in the situation, what would you recommend for the average Canonet owner looking for an adapter?

Well, I wouldn't put my knowledge that high - I have no training in sub-atomic physics at all. I do have some years experience in building adapters for a range of uses. My "best solution" for the Canonet would be to put a shottkey diode in series with the battery carrier (there is room inside) and use a SR44 with one of the turned aluminum or brass space "adapters".

Alternatively, make one yourself from a spent PX625 and diode (instructions on the net). If your skills are not up to that, one of the Netherland ones would be a good choice.

I have a batch of about 15 half built, but having to use a silver based solder means that I am heat damaging the diodes while trying to solder them. The extra heat to successfully flow the new solder is not that much more than the old lead based stuff, but just enough to give me a reject rate of 80+%, which is just too high to live with.

 

[john neal]

Which one does? My FTn meters seem to stay in the sub-mA range. Ok, AE cameras and cameras with electronic displays pull more. But most plain old match needle CdS camera are very low current devices at least unless pointed at a very bright light - many did not even have a off switch, their battery consumption inside the average camera bag being negligibly small.

Well, the Gossen for one, and I have seen Nikon F2 bodies that were into milliamps. Having said that, I would agree with your generalisation that most older meters will be in the uA range. My point really was that the Canonet draws 500 uA or thereabouts, while the Cris is only designed to work up to 200uA.

I will say again, nothing against Cris or Kanto as fine products, working within their design envelope.

 

[Solinar]

An important note: it seems that you need to wire a 10K ohm resistor in parallel between the test leads of the voltmeter in order to check whether there the required drop in voltage from a MR-9 adapter is present.

The 10K ohm resistor is a bypass that simulates your analog meter. In other words, if you are testing the adapter without a load in the circuit, you are doing it wrong.

See the following link, second paragraph in the section called "Limitations":

http://www.smallbattery.company.org....r9_adapter.htm

Best Regards,