Re: Milky Candle Pilot Run... (SOME NEW PHOTOS).
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Minjin said:
Two comments. First, if you're going to use a white LED, please leave the option for the user to solder on a red LED and switch. This would make a great nightlight and red would be a little better in that respect. More efficient and better on the eyes.
Secondly, what do you guys think about using other batteries with this? I inevitably have a bunch of batteries that come from lights that I'm sure still have more juice in them. If at all possible, I'd like to solder on a plug to allow external battery packs. Do I really need to worry about making sure that the batteries are all at the same charge? If I have a whole bunch of old AAs(lets say 12) and I divide them into three banks of four in series, do I really need to worry about one bank eventually trying to charge the other bank?
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Mark,
Interesting thoughts. Red LEDs, of course, have another advantage in that they can be driven from a single 123 cell (in fact the second cell in the MC is a 'waste' in this use). And yes, they make great nightlights. I've got half a dozen spread aournd the house, they need charging once a month (except the ones with photocells, which go two months).
And for sure there's nothing sacred with the 2X123 configuration, any source .1 Volt or more higher than Vf will work fine. If the goal is to drain old cells dry (and it sounds like it is) I see nothing wrong with not matching cells. A large series/parallel bank like you propose should be fine.
As a suggestion, since you can solder, why not go to
WorldTorch and order the DIY kit for four dollars (including shipping)? It has all the parts I used in the original MC circuit (except the center off switch, a 'Radio Shack' part), even includes a white LED to get you going. You get a small (roughly 3/4 by 1/2 inch) perf board assembly at any of the three original currents (or any other you'd like if you supply the resistor), all three if you supply a center off switch.
FWIW, I too have the 'two color bug' and have built several versions of this circuit that feature just this (two LEDs and a switch to select them), including one that has snap connectors on it so you can clip it on a 3 or 4 AA cell holder (or a 9 volt battery in a pinch). Not all that useful, but fun to play with.
FWIW, my favorite power source remains 3 NiMH cells. Honest efficiencies over 90% are easily possible. It's also interesting at 12 Volts with 3 (white) LEDs in series.
So, that's my advice, get the DIY kit and invent a candle of your own......
Doug Owen