Illum
Flashaholic
http://www.amazon.com/dp/B006XALSVG/?tag=cpf0b6-20
Bought one of these $5 lanterns because shipping was free. Performance-wise I was not expecting much, but at least it appears to be a good host.
Five weeks later it arrived and I was right. The stock configuration the output was absurd. oo:Extremely bright, extremely blue, and washes out all color where it was placed. :shrug:
So... I dropped $15 worth of parts in to improve a $5 lantern.:devil:
The design is actually 3 out of 5 for me [as opposed to 1]. The obvious lack of water entry protection was obviously frustrating, but the good thing is everything screws apart and is relatively splash resistant in the stock form. The bottom is held up by two screws, again zero seals. The switch uses a rigid black cap that "could" be replaced with a rubber GITD tailcap boot.
What the lantern looks like with the window removed. 11 T1-3/4 wide angle white LEDs, generic, and lights more blue than white. As it turns out there's no current limiting resistor!
11 LEDs in parallel direct drive by 3AAs! I speculate the designers used the lowly peanut duty carbon zincs as opposed to manganese dioxide alkaline batteries to test their products. The high internal resistance compensates for the lack of an inline resistor by sagging working voltage in response to the current draw of the LED array. :thumbsdow
On new coppertop alkalines, I measured 580mA across the circuit. That's half an amp into 11 LEDs, averaging then 52mA per LED! That's over two and a half times the recommended maximum forward current of an off the shelf T1-3/4.
In attempt to compensate for this I added a suitable resistor [as a reliability mod :duh2:] to reduce the current overload at 3AA. Since the LEDs typical forward voltage at rated maximum forward current is about 3.6V, operating direct drive with 2AAs is not an option, it would be so dim you can't get work done. With the newly added resistor the output wipes out around 3.2V. Rendering the light useless despite the batteries still holding 80% of their juice [~1V/cell] :scowl:
Rummaged through the parts drawer, found a [now obsolete:shakehead] CREE XPE warm white (2700-3300K) 20mm star that might help with the tint, as well as a spare NCP1402 DC-DC converter that will boost the juice from two batteries up to 3.3V. An inline 4.3R resistor will decrease the forward voltage of the LED, latching it in relatively stable regulation of about 110mA max. Max power dissipation was calculated to about 65mW across the resistor, but I opted for a 1/2W anyway. :tinfoil:
As shown here is a 1/16" aluminum plate fabricated to match the stock LED PCB, the 20mm LED board wired, and the converter in the back.:huh:
Test fit of the LED and plate alignment, first timers luck, dropped right in.:thumbsup:
Given the expense at it is, I really don't want to bother with providing hardware to mount the LED. So I opted to use an old fashioned method: zip ties.:nana:
The zip ties are threaded through holes drilled close enough to the star board to prevent it from shifting. LED power dissipation calculated about 300mW, very unlikely the plate will get warm at all. The LED is a 3W, so unlikely it will ever burn out or show phosphorous degradation from this application. Just to be on the safe side, I dropped a dab of thermal paste underneath.
4.3R 5% 1/2W inline resistor now soldered. This resistor drops about 0.4V, reducing the forward voltage of the LED to about 2.8V, resulting in the 110mA forward current characteristic. If needed be, this resistor can be adapted to run the LED at any current between 5mA and ~200mA [limited by the converter]
Wiring up the converter. The great thing about the battery holder is the readily available solder tabs to configure battery output. Common ground, 1.5V, 3V, or 4.5V. I unsoldered the 4.5V positive wire then soldered it onto the 3V positive, thereby eliminating the need of the third battery. The driver is soldered so that the push button switch determines if the converter is on or off. This eliminates any parasitic current that may be present while the lantern is in storage.
Converter http://www.pololu.com/product/2114
Slipped the driver in some heatshrink for support then mounted it with a slick of masking tape. Good thing about masking tape is that notes can be written on them with great clarity. Parts are labeled in the event down the road I'll have to pull them for other stuff
Final assembly, connecting the wires leading to the LED, seal with heatshrink.
Back in the house, side by side with the stock lantern. Its considerably dimmer but by far more pleasant than the stock output. With 2 AA batteries forward current draw is about 150mA, averaging a power consumption of 450mW and an anticipated runtime of ~7 Hours. Warm white tint averages 3000K and produces good color rendition.
Way overexposed unfortunately, cellphone cam
Output of the stock lantern. Extremely bright, mediocre color rendition weighted to the blue end of the spectrum. Forward current draw from 3 AA batteries is 580mA, averaging power consumption 2.4W and an anticipated runtime of about 3 hours, or till the LEDs begin to overheat and die.
Side by side comparison, the improved version looks by far dimmer, and it is under the light of the stock one. All these pictures are taken by cellphone, I have no way to lock the exposures. It looks dimmer than it is
This looks alot closer than what I see on my desk. Very useful, zero glare, zero artifacts. :wave:
Anyway, it was a 2 hour build entirely for fun. Just thought I'd share it. :tired:
If you want me to take it down, I'll take it down, it probably doesn't fit the homemade category because I did not machine the body
Bought one of these $5 lanterns because shipping was free. Performance-wise I was not expecting much, but at least it appears to be a good host.
Five weeks later it arrived and I was right. The stock configuration the output was absurd. oo:Extremely bright, extremely blue, and washes out all color where it was placed. :shrug:So... I dropped $15 worth of parts in to improve a $5 lantern.:devil:
The design is actually 3 out of 5 for me [as opposed to 1]. The obvious lack of water entry protection was obviously frustrating, but the good thing is everything screws apart and is relatively splash resistant in the stock form. The bottom is held up by two screws, again zero seals. The switch uses a rigid black cap that "could" be replaced with a rubber GITD tailcap boot.
What the lantern looks like with the window removed. 11 T1-3/4 wide angle white LEDs, generic, and lights more blue than white. As it turns out there's no current limiting resistor!
11 LEDs in parallel direct drive by 3AAs! I speculate the designers used the lowly peanut duty carbon zincs as opposed to manganese dioxide alkaline batteries to test their products. The high internal resistance compensates for the lack of an inline resistor by sagging working voltage in response to the current draw of the LED array. :thumbsdowOn new coppertop alkalines, I measured 580mA across the circuit. That's half an amp into 11 LEDs, averaging then 52mA per LED! That's over two and a half times the recommended maximum forward current of an off the shelf T1-3/4.
In attempt to compensate for this I added a suitable resistor [as a reliability mod :duh2:] to reduce the current overload at 3AA. Since the LEDs typical forward voltage at rated maximum forward current is about 3.6V, operating direct drive with 2AAs is not an option, it would be so dim you can't get work done. With the newly added resistor the output wipes out around 3.2V. Rendering the light useless despite the batteries still holding 80% of their juice [~1V/cell] :scowl:
Rummaged through the parts drawer, found a [now obsolete:shakehead] CREE XPE warm white (2700-3300K) 20mm star that might help with the tint, as well as a spare NCP1402 DC-DC converter that will boost the juice from two batteries up to 3.3V. An inline 4.3R resistor will decrease the forward voltage of the LED, latching it in relatively stable regulation of about 110mA max. Max power dissipation was calculated to about 65mW across the resistor, but I opted for a 1/2W anyway. :tinfoil:
As shown here is a 1/16" aluminum plate fabricated to match the stock LED PCB, the 20mm LED board wired, and the converter in the back.:huh:
Test fit of the LED and plate alignment, first timers luck, dropped right in.:thumbsup:
Given the expense at it is, I really don't want to bother with providing hardware to mount the LED. So I opted to use an old fashioned method: zip ties.:nana:
The zip ties are threaded through holes drilled close enough to the star board to prevent it from shifting. LED power dissipation calculated about 300mW, very unlikely the plate will get warm at all. The LED is a 3W, so unlikely it will ever burn out or show phosphorous degradation from this application. Just to be on the safe side, I dropped a dab of thermal paste underneath.
4.3R 5% 1/2W inline resistor now soldered. This resistor drops about 0.4V, reducing the forward voltage of the LED to about 2.8V, resulting in the 110mA forward current characteristic. If needed be, this resistor can be adapted to run the LED at any current between 5mA and ~200mA [limited by the converter]
Wiring up the converter. The great thing about the battery holder is the readily available solder tabs to configure battery output. Common ground, 1.5V, 3V, or 4.5V. I unsoldered the 4.5V positive wire then soldered it onto the 3V positive, thereby eliminating the need of the third battery. The driver is soldered so that the push button switch determines if the converter is on or off. This eliminates any parasitic current that may be present while the lantern is in storage.
Converter http://www.pololu.com/product/2114
Slipped the driver in some heatshrink for support then mounted it with a slick of masking tape. Good thing about masking tape is that notes can be written on them with great clarity. Parts are labeled in the event down the road I'll have to pull them for other stuff
Final assembly, connecting the wires leading to the LED, seal with heatshrink.
Back in the house, side by side with the stock lantern. Its considerably dimmer but by far more pleasant than the stock output. With 2 AA batteries forward current draw is about 150mA, averaging a power consumption of 450mW and an anticipated runtime of ~7 Hours. Warm white tint averages 3000K and produces good color rendition.
Way overexposed unfortunately, cellphone cam
Output of the stock lantern. Extremely bright, mediocre color rendition weighted to the blue end of the spectrum. Forward current draw from 3 AA batteries is 580mA, averaging power consumption 2.4W and an anticipated runtime of about 3 hours, or till the LEDs begin to overheat and die.
Side by side comparison, the improved version looks by far dimmer, and it is under the light of the stock one. All these pictures are taken by cellphone, I have no way to lock the exposures. It looks dimmer than it is
This looks alot closer than what I see on my desk. Very useful, zero glare, zero artifacts. :wave:
Anyway, it was a 2 hour build entirely for fun. Just thought I'd share it. :tired:
If you want me to take it down, I'll take it down, it probably doesn't fit the homemade category because I did not machine the body
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