this is the whole camera-equipment: 1 canon digital-ixus (incl 128mb+accu), 2 128-mb compact-flash-cards, 1 replace-accumulator, 1 battery-charger, 2 key-cases.

beside the new 'fluff-free direct-scan' a major advantage is to charge the accus without the main power-supply-system.

no big charger, no mains-cable, no adapter-plugs. the little circuit is just sticked to bicycle-dynamo + the accu will be charged 'by the way' (word-to-word).

apart from my philosophy of 'minimal baggage' this time i enjoy most to have made my photos in fact 'with my own strength' (except the one above :->).

with that i have carried home 1991 photos in 69 days. after 7ooo km of shaking, about 3ooo km of charging, usually 3o-4o degrees of heat, clouds/fog/rain. as well as the 2o km 'downhill-run' from the -at that time more calming- mount etna in 3o min.
(more about the photos)



the circuit, developed with a friend (thanx armin!), which eg could be tested with cellular-phones-accus, we like to present here more detailed. also when my li-ion-accus obviously yet show their 5o-min working-capacity, first of all this relevant information:

! TO THE APPEARANCE OF EVENTUALLY POSSIBLE (RESULTING)DAMAGE, WHEN OPERATING THE CIRCUIT(NO-AUTO-SWITCH-OFF) BELOW, IS STRICTLY REFERRED HERE (ESPECIALLY CONCERNING THE ACCUS) AND THAT THE AUTHORS DO NOT ACCEPT ANY LIABILITY FOR THAT !

parts-list: 5 schottky-diodes 1ooo mA o.5W, 1 z-diode 4.7V 1W, 1 5.6 ohm metal-layer-resistor o.6W, 1 bf 245c fet, 1 irf 52o n fet, 1 led 1.8V, 1 potentiometer 1-1o ohm, 1 electrolytic-capacitor 47o yF >35V, about 5 1 ohm metal-layer-resistors o.6W to xchange the potentiometer.

cooling-jacket, soldering-iron, universal measuring-instrument (o-5V), universal power-supply-unit, several voltages (eg 3-12V, 5oomAh), stranded-wire.

the charging-unit can be set up for a limited charging-current. a led indicates this. !!! cause there is no switch-off-mechanism in every case the charging-time has to be looked at responsibly (bubbles/danger of xplosion) !!!

in my case for km-assessing + protection of the 68o-mAh-accu i have limited the charging-current to about 35o mA, so that it is full after 4o-6o km. (the 5oo mA-melting-fuse kept up - the mount etna downhill, too :->)

en detail: after rectifying + smooting electrolytic-capacitor with the transistor bf 245 at the z-diode a voltage of 4.7V will be stabilized.

without resistor rs the whole possible current of the dynamo will be switched through. with rs this can be limited to an individual maximum.

cause of the parts-differences it has to be adjusted. best with different voltages + instead of the accu a ceramics-resistor or even none at all (short-circuit). as a precaution at least fix a danish 2-crowns-coin on the transistor irf 52o n :-> (cooling-jacket)

now with the potentiometer you can size as you like a maximum-current, which can be calculated by the measured voltage at the led/(r-led). then the 'moveable'-resistor can be replaced by a suitable row/parallel-arrangement of 1-ohm-resistors.

to build a reasonable accu-holding-device probably is the most work. the indirect charging eg via a cellular-phone-plug into the phone-charging-unit is not tested yet.

! much pleasure + success !

to enable everyone the chance for trying-out, we present the circuit here for free. allthough 'at every-corner' we are missing financial-foundations. therefore we are glad for every voluntary grant by enthusiastic, financially-stronger readers. for more cyrcles + new ideas.

harald herolp@web.de

digifoto-3/2oo2 (also in english) - extended guidance: leaf-through single-sheet (only german)


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