Extremely simple red LED mini mag mod?

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BatteryCharger

BatteryCharger

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The crazy guy next door
I have a red keychain light that I keep by my bed, it's nice because it doesn't hurt my eyes after I've been in the dark all night. I was thinking about modding a mini mag with a red LED. Wouldn't a red LED drop in perfectly in place of the bulb? And don't red LEDs run on 3v? Seems to easy.... /ubbthreads/images/graemlins/smile.gif
 
You want a resistor limiter, red leds actually want around 2.4 volts. You could get a Photon II or something like that. CMG Infinity with red led is also a nice bedside light (I have one next to my bed).
 
Actually, it would be running of NiMh AA's, so it would be pretty close to 2.4v. Would that be ok to direct drive? The current keychain light I have runs the red LED directly off of a 3v lithium coin...
 
If money's no object, how about one of the LED conversions (I have an Opalec Newbeam, which I like a lot) and the Minimag accessory kit with the red lens & lens holder?

- Dwayne
 
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BatteryCharger said:
Actually, it would be running of NiMh AA's, so it would be pretty close to 2.4v. Would that be ok to direct drive? The current keychain light I have runs the red LED directly off of a 3v lithium coin...

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'Yeah, but...', that coin cell isn't putting out 3.0 Volts when the LED is being driven. Mind you, those gadgets *severely* overdrive the LED when fresh, but in general it depends on fairly big internal resistance from the coin cell, that plus the bulk resistances in the LED itself are what end up limiting the current. Something has to since LEDs aren't naturally power limiting like normal bulbs.

In general, 'direct drive' is probably a bad way to go with respect to run time and useful light out. Some sort of regulation, even from a simple external resistor is called for (which is why it was suggested).

That said, the right Vf LED and sticking strickly to two NiMH cells should work fine. Measure the current (easy to do at the bottom end of the tube) and be sure you're reasonable (and watch for ones 'hot off the charger') and you should be fine.

FWIW the version of this I made for the car (hard to read some of the dash at night...) uses a resistor and alkalines.

Doug Owen
 
That was my first LED light, a 2 AAA mag with a 3mm red dropped in. It works fine, a bit over driven (although not as much as many of the premade ones) with alkaline, and a bit under driven with NiMH.
 
wow I was just thinking about this! It's just AA's so I would not really care about runtime...

Why again should I not DD? I have an F rated Lux I Red...

Acording to the spec sheet a red HD can take about 3.5 volts, especialy if it is a higher Vf bin...

The hard part will be Heatsinking, would maybe a flattened penny or dime work? And I guess I can't use AS epoxy unless it is the whole star and not just the emitter?
 
A better red led mod is the following-
A Rayovac 2AA rubberized industrial light. The light is solid and has a good switch. You can put the led + 33 ohm resistor in a PR bulb. The neat part about this is that you can bypass the switch with a 1000+ ohm resistor. The resistor is placed in the rubber covered rib that runs the length of the light.

This leaves a constant-on dim red light which runs all night and is just bright enough to be visible. When you click the switch, the red led goes to full brightness. The batts are only drawing about 1/2ma during constant-on.
 
I don't know about red led, but I drive several green LEDs with 2AA Alkaline or 3N Alkaline just peachy.

I poofed one with 2x123 and I might have killed another with 3AA though I'm not sure.

I seem to remember having some other LEDs including red out of a grab bag. Going to look around and play a bit!
 
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StuU said:
A better red led mod is the following-
A Rayovac 2AA rubberized industrial light. The light is solid and has a good switch. You can put the led + 33 ohm resistor in a PR bulb. The neat part about this is that you can bypass the switch with a 1000+ ohm resistor. The resistor is placed in the rubber covered rib that runs the length of the light.

This leaves a constant-on dim red light which runs all night and is just bright enough to be visible. When you click the switch, the red led goes to full brightness. The batts are only drawing about 1/2ma during constant-on.

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Oh geez...now this "extremely simple mod" has turned into a "get out your soldering iron mod". /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/wink.gif

So where do I find the brightest 5mm red LEDs?
 
Years ago I picked up a LED assortment pack from Radio Shack and spent a fun 5 minutes plugging them in a maglite in place of the bulb. Went in my bathroom with no windows and closed the door each time. My bathroom is so small you can brush your teeth, use the commode and shower at the same time and none of those LEDs could light up the opposite wall.
 
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Eugene said:
Years ago I picked up a LED assortment pack from Radio Shack and spent a fun 5 minutes plugging them in a maglite in place of the bulb. Went in my bathroom with no windows and closed the door each time. My bathroom is so small you can brush your teeth, use the commode and shower at the same time and none of those LEDs could light up the opposite wall.

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Those were probably LEDs meant to be used as an indicator on something. For example, the green LED on your keyboard that lights up when cap locks is on would never work as a flashlight, but there are other green leds that run on the same voltage that are extremely bright.
 
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BatteryCharger said:
Wouldn't a red LED drop in perfectly in place of the bulb? And don't red LEDs run on 3v? Seems to easy.... /ubbthreads/images/graemlins/smile.gif

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As has been mentioned, you might want to think about limiting the current through the LED. Think about for about 30 seconds. Then get a red LED, stuff it in the bi-pin mag socket, drill out the reflector a tad, and it'll be fine. Good grief, even if it does burn out, you're out, what, about $1?

Anyway, I've tried it and had no trouble.
 
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Justintoxicated said:
Why again should I not DD? I have an F rated Lux I Red...

Acording to the spec sheet a red HD can take about 3.5 volts, especialy if it is a higher Vf bin...

The hard part will be Heatsinking, would maybe a flattened penny or dime work? And I guess I can't use AS epoxy unless it is the whole star and not just the emitter?


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You can definitely direct drive a red Luxeon in a MiniMag. It will draw less than 250mA, so you won't need heatsinking at all. You can use any kind of AA's. Now if you were to add a current regulator, then you would need a heatsink.

For my mod, I used the original bulb holder and battery contact, and ran wires up from the anode and cathode contacts, the same way the bi-pins were routed. I filed a groove in the battery holder on a line with the 2 bi-pin holes, and then I super-glued the wires in place in those grooves and super-glued the Luxeon in place. I drilled out the original reflector to fit over the emitter, and screwed it down over the emitter while the super-glue was wet, this centered the emitter, and held it in place while the glue dried. Since the wires were held in place by super-glue, when I bent them to touch the luxeon contacts, they stayed in place without any solder.

Then I put in an NX05 optic with an o-ring from Dat2Zip. I also added a Kroll clickie. For me, this made the MM feel like a real flashlight. It does have the disadvantage that you have to remove the Kroll in order to change batteries.

I tried a Fraen low profile optic, which makes a very round and smooth beam, but I like the NX05 better, because of it's useful spill. That is to say, you can see more of what you are looking at.

It runs for over an hour on rechargeables. I got tired of testing the run time after an hour and 10 minutes. This convinced me that I didn't need to spend over $5 for 2 lithium batteries. I calculated that lithiums should run at full strength for 9 or 10 hours, maybe more with internittent use.

Yeh. This is an easy mod for sure and the results are nice, if you enjoy pure red light. Since the whole thing is modular, I can easily undo all the changes.

I wrapped some plastic from a sandwich bag around the threads at the top of the battery tube, to hold the head securely in place.

Don't forget that if you add a heatsink, you have to make certain that the emitter slug doesn't make contact with a negative charge.
 
[ QUOTE ]
BatteryCharger said:
I have a red keychain light that I keep by my bed, it's nice because it doesn't hurt my eyes after I've been in the dark all night. I was thinking about modding a mini mag with a red LED. Wouldn't a red LED drop in perfectly in place of the bulb? And don't red LEDs run on 3v? Seems to easy.... /ubbthreads/images/graemlins/smile.gif

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You have to use a Multimeter to measure the current draw of your led when it is powerd by 2 AA's. Only then will you know if you need a resistor, and how big it should be. Not all led's are the same. For instance, I have a green led that runs at 30mA with no resistance when powered by 3 D cells, or one 3.7 volt Li-ion rechargeable. Flashlights require empirical science, not theoretical science.
 
I have some really bright red LEDs that I think I got from all electronics, and I've been driving them from 2xAA for a long time and haven't blown one yet. I've done a bunch of 2 cell mods with these. They are rated at 2.0 - 2.4V but seem to shrug off a 3V overdrive.

This should be it...

They are the brightest 5mm LEDs I've seen.
 
[ QUOTE ]
BatteryCharger said:
[ QUOTE ]
Eugene said:
Years ago I picked up a LED assortment pack from Radio Shack and spent a fun 5 minutes plugging them in a maglite in place of the bulb. Went in my bathroom with no windows and closed the door each time. My bathroom is so small you can brush your teeth, use the commode and shower at the same time and none of those LEDs could light up the opposite wall.

[/ QUOTE ]

Those were probably LEDs meant to be used as an indicator on something. For example, the green LED on your keyboard that lights up when cap locks is on would never work as a flashlight, but there are other green leds that run on the same voltage that are extremely bright.

[/ QUOTE ]

I was hoping the assortment was going to be more assorted and would have a bright one or two. There were some that were brighter than others but nothing decent for a flashlight.
 
I've done this before and it works fine, although I tried mine by putting 2 LEDs side by side. Why not stick 7 5mm LEDs in a hexagon configuration with 2 on the first row, 3 on the second, and 2 again on the third? That can easily fit in a minimag once you take off the useless reflector.
 
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