kamil_k
Member
Hi Guys!
I am trying to get my Minolta Hi-Maitc to work with two adapters (SR-44 + BAT83). There has been a lot written about Mercury battery replacements in the last years however however the focus was only put on adjisting the voltage. What has been neglected however is the amperage. In the paper "The mercury cell problem and its solutions" you can see how the power consumption (in mA) influences the Voltage drop of different diodes used for the adapters. As the power consumption increases the voltage follows aloong the slope beyond the point where there is not enough power to supply the camera.
You can also find the following statement: "The ‘battery check’ reading on a camera or exposure meter may give erroneous readings when a battery adapter is used because the ‘load’ of the test circuit may be too high, this does not mean the adapter does not function properly. When a fresh silver-oxide cell is used with an adapter, mark or remember this ‘battery check’ reading and use it as a new ‘full battery’ reading when using an adapter." From what I read i.e. the CRIS adapter doesn't transmit more than 200mA which may cause the battery check function not work in some cameras.
It seems to be my case: I cannot get a readying from the battery check. However the shutter itself seems to be working (I tried it in a dark room - I get the warning light, the shutter opens and closes. If pointed directly against a light source you can also see that the shutter is closing faster than in dark conditions). I measured the voltage of both adapters with a multimeter - I get 2.8-2.85 V in total when they are installed in the camera. I installed two fresh SR-44 cells. The voltage generated by fresh silver oxide cell may be a bit higher than 1.55 (1.6V) unti it settles at 1.55. Therefore I hope my batteries would get even closer to the required 2.7V over a short periode of time.
I am however not sure how much power does the shutter and the cds lightmeter consume during operation. It may have a significant influence on the actual power generated by two adapted silver-oxide cells which will translate to incorrect exposure.
Minolta Hi-Matic F and E use the Electro Conrol system known also from Yashica Electro. Unlike many other compact rangefinders of that era, Electro Control needs more power to operate properly - therefore Hi-Matic needs two px640 Batteries and 2.7V vs ie. single 1.35 cell. But how much is this "more" ? So far my experiences with using unadapted batteries with the Hi-Matic F show that it does make a difference and adjusting ISO by -1 EV works only in certain conditions. There has been enought written about it as well. I would like to avoid weeks/months of adjusting different combination (ISO compenmsation, using 1 unadapted + 1 cell with with adapter etc.). I'm not an expert and hope someone could help me to figure out the right setup.
Does anyone of you have any closer information about the power (apart from the voltage) required for Hi-Matic F to operate properly? Or maybe has already tried to use two adapters to operate the camera?
I am trying to get my Minolta Hi-Maitc to work with two adapters (SR-44 + BAT83). There has been a lot written about Mercury battery replacements in the last years however however the focus was only put on adjisting the voltage. What has been neglected however is the amperage. In the paper "The mercury cell problem and its solutions" you can see how the power consumption (in mA) influences the Voltage drop of different diodes used for the adapters. As the power consumption increases the voltage follows aloong the slope beyond the point where there is not enough power to supply the camera.
You can also find the following statement: "The ‘battery check’ reading on a camera or exposure meter may give erroneous readings when a battery adapter is used because the ‘load’ of the test circuit may be too high, this does not mean the adapter does not function properly. When a fresh silver-oxide cell is used with an adapter, mark or remember this ‘battery check’ reading and use it as a new ‘full battery’ reading when using an adapter." From what I read i.e. the CRIS adapter doesn't transmit more than 200mA which may cause the battery check function not work in some cameras.
It seems to be my case: I cannot get a readying from the battery check. However the shutter itself seems to be working (I tried it in a dark room - I get the warning light, the shutter opens and closes. If pointed directly against a light source you can also see that the shutter is closing faster than in dark conditions). I measured the voltage of both adapters with a multimeter - I get 2.8-2.85 V in total when they are installed in the camera. I installed two fresh SR-44 cells. The voltage generated by fresh silver oxide cell may be a bit higher than 1.55 (1.6V) unti it settles at 1.55. Therefore I hope my batteries would get even closer to the required 2.7V over a short periode of time.
I am however not sure how much power does the shutter and the cds lightmeter consume during operation. It may have a significant influence on the actual power generated by two adapted silver-oxide cells which will translate to incorrect exposure.
Minolta Hi-Matic F and E use the Electro Conrol system known also from Yashica Electro. Unlike many other compact rangefinders of that era, Electro Control needs more power to operate properly - therefore Hi-Matic needs two px640 Batteries and 2.7V vs ie. single 1.35 cell. But how much is this "more" ? So far my experiences with using unadapted batteries with the Hi-Matic F show that it does make a difference and adjusting ISO by -1 EV works only in certain conditions. There has been enought written about it as well. I would like to avoid weeks/months of adjusting different combination (ISO compenmsation, using 1 unadapted + 1 cell with with adapter etc.). I'm not an expert and hope someone could help me to figure out the right setup.
Does anyone of you have any closer information about the power (apart from the voltage) required for Hi-Matic F to operate properly? Or maybe has already tried to use two adapters to operate the camera?
cwiley123
Newbie
Minolta Hi Matic battery Adapter
Minolta Hi Matic battery Adapter
I'm unsure of the current (amperage) required but I turned an adapter out of brass stock and use a #675 hearing aid battery. They are 1.4 volt zinc air batteries and the meter and battery check light work fine in my Hi Matic 7S.
Minolta Hi Matic battery Adapter
I'm unsure of the current (amperage) required but I turned an adapter out of brass stock and use a #675 hearing aid battery. They are 1.4 volt zinc air batteries and the meter and battery check light work fine in my Hi Matic 7S.
kamil_k
Member
Hearing aid/zinc air batteries are my plan B. The battery check did light up when I had two '675' in the camera. One can also use small coins to compensate for the size difference between 675/SR44 and px640. I just use three 1 eurocent coins and they fill the gap in the compartment perdectly in combination with the battery - no fancy adapters required.
The lifetime of zinc air batteries is however too short for me - I don't want to remember to change batteries every few weeks. Therefore I hope that two adapters with Shottky diodes will do the work.
The lifetime of zinc air batteries is however too short for me - I don't want to remember to change batteries every few weeks. Therefore I hope that two adapters with Shottky diodes will do the work.
Moto-Uno
Moto-Uno
^ Aren't those zinc batteries dirt cheap ? Peter