Mr.X
Joined: 01 May 2004
Posts: 216
Location: Portland, Oregon U.S.A.
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 Posted: Mon Dec 05, 2005 10:12 am Post subject: Limited current supply from the 2016 cells. |
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| Psillynilly wrote: | | The max operating voltage for an LED is 4.1 volts....however, photons all run on 6 volts. I think I found a tiny carbon-O resitor (101 ohms) built into the P3 and ravn's processor but the P2's secret remains a mystery. SOmebody once told me the small amps the 2016 disc batteries put out lets the LED take 6 volts without being harmed but Im not sure this is true. Any insight? |
Dear Psillynilly,
The "101" resistor you have found so often, in the Photon lights, is not a 101 ohm resistor, but rather, a 100 ohm resistor. The third character is a multiplier(by powers of 10). So... if the resistor was marked 102, that would mean it was a 1000 ohm resistor. 103 would equal a 10,000 ohm resistor. If it was marked 100, then it would be a 10 ohm resistor. It is the same as the basic resistor color code, only using numbers instead of colors. The small surface mount resistors aren't large enough to print 1,000 or 10,000 on them, so they use the "two digits and a multipiler" method. So, a resistor of this type, marked 562 would be 5,600 ohms.
Also--
None of the Photon Lights run on 6 volts and there are no resistors in the Photons 1 & 2. It is the limited amps(effective internal impedance) of the 2016 cells that protects the leds and allows the current to "load down" the cells to around 4 volts.(As Bryan noted.) This is why, if you use a full 6 volts from another power source, you will overload the led. Unless you add more resistance to make up for the difference, the LED will draw too much current from the power source. Even if all you use is two 2032 cells, an un-modified Photon may draw too much current from those two batteries and will likely overdrive the LED and the controller chip, perhaps to distruction.
This is probably why you have lost a number of P3 Photons, as I have read about in some of your earlier posts. Running the Photons on an alternate 6 volt supply, with a higher current capability (than two 2016 cells), will force the running voltage above 4.5 volts, overloading the led and likely causing damage to the controller chip as well. I am guessing that you used larger batteries. This is why those Photons had such a short life, as you have told us about.
I believe you will also find that the Red, Orange, Yellow, & IR LEDs are not normally run on 4.1 volts, but closer to 2.2-2.6 volts. This works well with the 2032 cells when they load down the cell to that level. Their long running time is due to the increased millamp/hour rating of the 2032 cell over the 2016 cell.
Is this the insight you were looking for?
You work hard on your lights and I would hate to see you lose more Photons for no reason.
Happy experimenting. 
Mr.X
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