IMPORTANT: reverse (!) the polarity of the 4 diodes in the ZENER row, I made a mistake! Sorry for that.
How to keep old 2000’s etc digital cameras in function.
Some of them have extremely good properties, like the Pentax Optio E 30, say from 2006-2008, but that Pentax was brought to early on the market in Europe.
With (even) two 2300 mA-Hour Nickel Cadmium batteries that Pentax Optio E 30 could only work for 10 Minutes or so, that is a classic manufacturer failure.
Anyway: that does not have to do anything (!) with their extremely good lenses and high-tech light-sensitive and high resolution photonic chips/sensors.
Often (say) in the past 4 or 7 Mega pixels, but with a high resolution…. Sometimes better than modern (2019) camera’s, though I have to say that the camera lens & photonic chips developments of the past years are immense (2013-2019).
So here I give a solution/idea for these old HQ camera’s: mount a (quite) fierce battery of 2,4 Volt that can give out a current of (say) 500 mA or 1 Ampère at 2,4 Volts during a few (or 1, or 2) hours.
Could be that other 2000’s camera’s need a higher or other supply voltage/current, the principles stay the same. When their supply batteries/accumulators are no longer available: make them!
Good for the environment to NOT through these camera’s away.
With a good battery the camera can/will work properly again for many hours/years.
The charger in case of the Pentax Optio E 30 can be (was) simple: the 4 normal Silicon power diodes (0,7-0,8 V barrier voltage), all in a row, parallelled to the 2,4 Volt (2000 mA – Hour) Ni Cad batteries act as a “zener” diode, that limits the charge voltage to (say) 4 x 0,7 V = 2,8 Volt or somewhat higher, with a sure effect on the charge current, given the situation that the Ni Cad cells can be charged to max. 1,3 up to 1,6 V.
The series diode (“3 A” in the drawing) prevents that the NiCad cells discharge “over” the charger unit.
Chargers for higher voltage for 1990’s camera’s can be made due to the same principles: study the datasheet of the used accumulator, replace it with simple NiCad batteries, if necessary as a kind of “block battery” outside the camera. Does not look nice and looks unprofessional, but who looks at it that way?
Use the “blocking” diode (any Si diode of say 300 V and 5 Amp will do the job) to prevent discharging of the batteries over the “charger” unit.
Even with a too high charge voltage/current (of course within limits, don’t go higher than say 18 Volts, check the charge current and charge voltage with the appropriate Amp. and Volt meters) that zener acts as a voltage and (thus) current current limiter to these 2,4 V/2200 mA-hour Ni Cad cells.
Best idea: slowly charge them to their peak. Of course: standard charge situation is 1/10 x the capacity, so here: 220 mA during 10 Hours (Ni Cad cell = 2200 mA/per hour) .
The Si diodes (“zeners” and blocking diode) can get warm or even hot, but they protect the two Ni Cad cells by limiting the voltage to them.
Do not over-charge NiCad cells, switch the charger “off” (time clock, for a few Euro’s to buy everywhere) when the NiCad cells are charged completely ofter complete depletion, or other wise (half depleted = half time).
With completey depleted NiCad cells the charge time can be calculated. 1/10 of the Ampère hour for which the NiCad cells were made is is normally safe, so a 2200 mA/hour Ni Cad cell needs 1/10 x 2200 mA/Hour = 220 mA charge current during during 10 hours).
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This video is an attribute to the many environmental questions, nowadays, say 16 June 2019.