1. Costco stopped carrying the Luxeon LED flashlights.
2. A couple of the Costco lights started to have intermittent problems.
3. I needed something brighter than the Dorcy AAA light, but still wanted to stick with a single or double AA design.

A few months ago I received a post on that older article from Nick at http://www.workflashlight.com.   I asked him if I could test a couple of his lights and he sent me two single AA models to try:

• 5W Super Duty 30 Lumens 1xAA Pocket LED Flashlight
• 1W 32 Lumens 1xAA LED Flashlight

Here are the two lights along side of the Dorcy AAA LED flashlight:

As you can see the beam of the 5w had a bit more of a yellow coloring while the 1w has more of a blue color similar to the Dorcy.   Both of these test lights had a much stronger and tighter beam than the Dorcy.  Pretty amazing when you consider the batteries in each are more or less the same (1.5 volts).

Next I setup my camera and each light to shine on a target picture 16 feet away.   I’ve found that while I’m outside checking on the chickens that this distance is usually the max distance of what I expect to see with a small form factor light light this.

	Here is the baseline shot of the wall and picture with the lights on.The image is cropped and zoomed to get better detail.Click any of the thumbnails to see a larger image.
	This is the 5W Super Duty 30 Lumens 1xAA Pocket LED Flashlight.Again, you can see that the color is a little bit on the yellow side, but could be considered more like “actual light” color. This light produced a good balance between the main beam with a decent amount of “side spill” for peripheral viewing.I prefer the feel of this light over the 1W below.  It seemed more solid and I liked the anti-roll notching into the body.
	This is the 1W 32 Lumens 1xAA LED Flashlight.  It has a more “blue” color and a tighter main beam with less side spill.While I preferred the feel of the 5W light above, this light fit more smoothly into my pocket.  I also liked the light color better.The tail cap button felt a little less solid on this light and the optics were loose (could have simply been this model).
	Here is the Dorcy AAA LED.  The light setting was fixed on the camera to provide for a relative display of how much light each of the flashlights produced.    The Dorcy was almost useless at this distance.

 Overall I was very pleased with the lights.   I’m not sure if it was an optical illusion produced by the different color light, but I honestly had a hard time determining which one was brighter.   After going outside in the dark and testing the lights on a plethora of different areas I decided I liked the brightness, color, and beam of the 1W 32 Lumens 1xAA LED Flashlight best.    While I like both lights, I think the 5W body with the 1W circuit / LED would be a perfect combo.

A big thanks to Nick at http://www.workflashlight.com for letting me test his lights.  Maybe someday he’ll be able to talk me into testing some of his brighter non AA based LED lights. 

The Nifty-Stuff LED Boost Circuit / Joule Thief is a device designed for two purposes:

1) To suck any and all traces of juice from your “dead” batteries.

2) To light an LED, with a voltage requirement of higher than 1.5 volts, off of a single 1.5 volt (or less) battery! For example, run a white LED from a single AA battery!

Other boost circuits exist. Some are more efficient but have more parts and are expensive. Others have fewer parts, but are not very efficient or reliable.

This circuit was built to be a perfect balance of price, efficiency, & reliability. Efficiency is around 70% with only 7 parts.

I made a few tap lights for my wife and some other nursing mothers to use at night. These lights are perfect for this application. Not too bright as to blind you when your eyes are adjusted to the dark but sufficient light to accomplish nightly tasks. I received some excellent feedback from one of the mothers:

“This seriously is a “magic” light. I mean, it gives off a decent amount of light, and the fact that it runs ten hours a night for over six weeks on two batteries is pretty crazy. I think this light would be great especially as a night light for kids’ rooms because it’s safe (doesn’t use an outlet), and it’s so cheap to use that you can let it run all night.”

I noticed that I was piling up a HUGE supply of dead alkaline batteries from use in baby toys, flashlights, etc. Being the miser that I am I hate throwing batteries away that still have a bit of juice in them. I was previously using my constant current circuit in a tap light for my wife. I decided to create a new tap light with the Nifty-Stuff LED Boost Circuit. I originally created the boost circuit tap light with two AA batteries in parallel. I stuck two “dead” batteries in the light and gave it to my wife. After a few weeks of use every night the light was still shining bright. At this rate I’d never get through my stockpile of dead batteries! I opened the tap light back up and re-wired the batteries to run in series. This provided more light and would drain the batteries faster. Hahaha… I never thought I’d be designing something to drain batteries faster… how funny!

Word has spread about my custom built lights and my boost circuit, so I’m making it available as a non assembled circuit. You’ll get all the parts needed to build the circuit including a high quality Printed Circuit Board (PCB).  Please keep in mind that this is a VERY tiny circuit, so you’ll need to be pretty handy with a soldering iron to avoid accidentally bridging two connections and shorting something.

The kit with all the parts (including a bright white LED) is currently unavailable.  If you would like to be notified when kits are available please post a comment to this post.   Sorry for any inconvenience

Using this circuit: This circuit may be driven by voltages up to 3 Volts. While the basic design goal was ‘candle like light from a single cell’, the components used were chosen to allow safe operation from 3 Volts so you can, for example, use it to ‘drain the last bit of energy’ out of used Lithium based cells from flashlights. This means that you can also drive it from a fresh 123 cell at full brightness or two NiMH, alkaline or other cells in series. While the current consumption (and therefore light output) goes down with supply voltage, some light is produced even with very low inputs.

I’ve had a lot of fun making up many different versions / modifications of these tap lights (also called touch lights, push lights, closet lights). Over the months I’ve received requests to make custom modified LED tap lights.

I noticed that on the net there aren’t many options available for LED Tap Lights or an LED touch light, etc. All I could find was an LED replacement bulb for a tap light, but it cost $10.00 just the bulb!

LED’s work so much better than incandescent bulbs. For example, the average runtime on 4 aa batteries for:4 LEDS: about 25 hours (depending on battery quality)
8 LEDS: about 12 hours (depending on battery quality)

I use to build custom LED tap light for people, but just don’t have the time. If you are crafty and can handle a soldering iron you can purchase my contant current circuit kit and build your own project. Also, check out my boost circuit kit.

—————————————–

Comparison of an LED light with the stock “nose” of the LED and with the tip ground down to diffuse the light:

Here are a few more tap lights I created. The “stock” tap light is in the middle.

The Solution:
For most of my LED applications a very special circuit was designed to run the LEDs at a “constant current”. This provides a constant amount of power to the LEDs and also provides a constant amount of light for a longer period of time. This circuit also allows the LEDs to run on almost any normal voltage above 4 volts. This means you can use multiple sources of power for the same light, a few AAA batteries, or even a car battery (see notes below)!

Here are the printed circuit boards and an assembled board:

A few notes about this circuit:

• This circuit runs under the following constraints:
  • Max output is 300 mA.
  • Maximum supply voltage should be less than 40 volts. (Higher power levels will require external heatsinks).
  • BOTH of the above have the condition that the max watts (Watts = Volts x Amps) through the circuit is 2000 milliwatts.
• Higher than necessary input voltage (input voltage above the load’s voltage requirement) leads to excess power, which may require heat sinking.  For example, if powering this circuit using a car battery you should try to use 3 leds in series which requires about 10 volts.  If you only use one LED (about 3 volts) then the circuit will become very warm and should use a heatsink.
• The circuit needs + 0.3 volts to work. For example, if you are using a white LED that requires 3.3 volts, the circuit will provide aconstant current until the voltage drops below approximately 3.5 volts. You may use “any” voltage above 3.5 volts ( if it meets the constraints mentioned earlier) and the circuit will provide constant current = constant light output. Once you go below 3.5 volts (in this example) the circuit basically goes out of regulation and you’ll get dimmer light until the batteries go dead. Incandescent lights powered by conventional batteries have this same problem. As the battery runs down the lower voltage will cause the LEDs to give out less and less light.
• The original circuit was made to run a single 5mm LED from 3 AA batteries for a VERY long time.
• LED configuration examples:
  • Six 5mm LEDs in parallel: Use a circuit designed for 120 mA (6*20) and an input voltage of at least 3.5 volts.
  • Six 5mm LEDs in series: Use a circuit designed for 20 mA and an input voltage of at least 20 volts (3.2*6).
  • 5 parallel strings of three 5mm LEDs in series: Use a circuit designed for 100 mA (5*20) and an input voltage of at least 10 volts (3.2*3). This makes a lot of light, an excellent solution for many automotive uses.
• The closer the circuit gets to 2000 mill watts the warmer the transistor will get, almost to the point that it is too hot to hold in your fingers. At this point you should be doing some heat sinking or cut back on power.
• If you are running LEDs in parallel you should consider using a small resistor (say 1-10 ohms) in series with each string of LEDs. This is to protect you from any defects or problems with an individual LED and to help prevent “thermal runaway”.

I’ve had a few people contact me about purchasing my constant current circuit. You can purchase a kit with all the parts needed to make this circuit from the link below:

What is included in the kit?

1 – Printed circuit board

1 – Transistor (MJE2955T) (Square head)

1 – .1 micro Farad capacitor (blue thing that looks like a match head)

2 – 360 ohm (Orange, Blue, Brown, Gold) resistors

1 – Integrated circuit (LM334 Current regulator IC)

4 – Current setting resistors (for setting the current from 2 – 65 mA)

1 – White LED

Please note: I’m unfortunately unavailable to provide support for this circuit.  Hundreds of these have been built using these specs and parts.  If you have experience with a soldering iron and especially if you’ve built electronic parts before, there shouldn’t be any issues at all.

The kit with all the parts (including a bright white LED) is only $11.00 with FREE shipping to the continental US.

Click HERE To Purchase A Kit

]]> http://www.nifty-stuff.com/constant-current-led.php/feed 13 http://www.nifty-stuff.com/honda-dome-light-led.php http://www.nifty-stuff.com/honda-dome-light-led.php#comments Fri, 10 Jun 2005 08:50:49 +0000 Rob http://www.nifty-stuff.com/wp/?p=21

This was actually one of the first LED conversions that I did, but I never posted it because I’ve been wanting to re-do it to make it nice and pretty.  The problem is that it works so well that I haven’t been pressed to make any changes.  This being the case I’m posting the modification as it is until I decide to change it.

When we bought our 1993 Honda Civic a few years ago one of the first things I noticed was that the dome light was terribly dim.  I thought it was a bad bulb, so I replaced it, but that didn’t make any difference.   It was a few months later that I started getting into LEDs so I created a really poorly done prototype.  It was three 3mm LEDs with a few resistors.   The problem (as mentioned on other pages of this site) is that the voltage from a car battery can fluctuate quite a bit from 11 – 14 volts.   LED’s really can’t handle this change so my first model was designed for the worst case scenario of 14 volts.  What happened was when the car wasn’t running the alternator the LEDs were pretty dim.

I promptly replaced this model once I learned about current regulating circuits like the ones mentioned here.   I also redesigned the light because it was hard for the LEDs to illuminate the car through the dome light plastic.  I wanted light that I could re-position to different parts of the car (for reading, spot lighting a section or to remove light from another.  I cut tiny little “V”s into the plastic and used solid strand copper wire attached to the LEDs with shrink tube.  Here is what it looks like:

 Above is a shot of the circuit.   You’ll see that I used perf board and have two 3mm LEDs in the middle for a little extra light.  I cut a paperclip and bent it in a “V” then soldered it to the board to make the contacts to fit where the bulb use to be.  I’ve got some electrical tape on the back to protect the soldering.

For most of these applications a very special circuit was designed to run the LEDs at a “constant current”. This provides a constant amount of light to the LEDs for a longer period of time and allows the LEDs to run on voltage from 4 volts to 12 volts. This means you can use multiple sources of power… even a car battery!

Here are the printed circuit boards that are used in many of my LED projects:

Here are a few special LED projects:

Tap light projects:

Here a customer requested a lighting solution for 50 table displays. Each table would have a trophy that would need to be individually illuminated. Below is the prototype and the finished units (a few of the 50 that were ordered).

An LED light circuit with a bunch of LEDs with their noses ground off. This diffuses the light and allows the LEDs to project light in a wider, more uniform pattern.

There are a TON of LED flashlights out there, but this one is my favorite: The Dorcy AAA LED Flashlight

Here are my criteria in rating this flashlight:

• Price
• Battery Type
• Runtime
• Brightness

The price is a major factor to me because I have a habit of either loosing, braking, or giving away flashlights.

Battery type is super important because I want to use rechargeables, or readily available batteries.

I want the light to be LED based for three reasons: 1) LEDs are just cool! 2) LEDs are more efficient than standard flashlight incandescent bulbs making the batteries last much longer. 3) LEDs are really cool!

Brightness is of course important with any flashlight, but isn’t the most important factor in my overall favorite LED flashlight. I just want to be able to see well enough to get by. I’ve got a rechargeable 1milllion candela spotlight that I use when I really need to see something far away, or something I really want to light up (for example, the raccoons fighting in the back yard).

The DORCY AAA LED flashlight is my favorite LED flashlight because it is a perfect blend of the following:

• Price – $6 – $8 at Walmart, Target, etc. (The red one below was $5.94 at Walmart on 9/17/04)
• Battery Type – 1 AAA battery
• Runtime – About 6 hours on a single battery!
• Brightness – Pretty bright considering light is produced from a single AAA battery and 5mm LED. Adequate for 95% of my needs.

As you can tell by the majority of my posts on this site I am very concerned with overall value. For the money spent I believe I’m getting a great LED flashlight! It is an inexpensive light that is compact and bright.

Update 4/3/05
While the Dorcy AAA LED light is great for so many uses, I found I needed something with a bit more oomph!  COSTCO TO THE RESCUE!

Costco started selling a twin pack of bright white Luxeon LED flashlights.   They came in a twin pack for $28… that’s $14 a light, and for a Luxeon Flashlight, that’s not bad.

Update 2/25/09: See my new post, LED Flashlight Review – AA Models

Buy Pre-Made Tap Lights Here

PROBLEM: The Mini Tap Light puts out too little light and drains too much juice!

SOLUTION: Replace the crappy little excuse for a bulb with EIGHT bright LEDs.

MATERIALS:
4 – bright white 3mm LED’s: 3mm, 3.3V, 30mA
4 – bright blue 3mm LED’s: 3mm, 3.3V, 30mA
1 – Mini Tap Light
8- 20 ohm resistor.

INSTRUCTIONS:First step is to take everything apart and remove the cheap christmas tree light bulb. NOTE: I marked the three pieces, the dome, lid, and base with a marker to make sure I put all the pieces back in the same spot… this WILL help!
Second step was to cut out a thin piece of plastic the size of a half dollar (a little more than an inch in diameter), something like this:

I used a punch to put holes into the plastic and slipped the LEDs into place. I used a hot glue gun to get the LEDs to stay in place and alternated between blue, white, blue… with all the positive leads in the center. I bent all the negative leads into an outer circle and soldered them all together. I soldered a resistor to each positive leg and had them all converge into the center where I soldered them all together. I then soldered some wires from the LED array to the base and switch. Finally I hot clued the assembly to the dome. I guess I could have just stuck it on the base, but I stuck it to the dome so the lights would be right up against the top.

(okay, so I didn’t have 20 ohm resistors and soldered 2×10 ohms together… sue me)Finally, I put everything back together (remember I marked the pieces for easier assembly)

Below I adjusted the settings on my camera so you could see the LEDs better:

For comparison, here are the two lights side by side. I measured the draw and even though the new LED tap light is MUCH MUCH brighter, the draw is about the same, even a bit less! The original light on the left draws 160 mA while the light on the right was drawing about 150 mA!

About a week after I made this mini tap light LED mod I ordered some industrial strength glow-in-the-dark powder. This stuff glows REALLY bright for about 3 minutes and can last up to 10 hours with pretty decent glow. I decided to put a little on the top of this tap light so I could find it in the dark. I created a little stencil and used clear fingernail polish. I laid on a thin layer of polish, dusted it with powder and let it dry. I did this about 5 times and then put a final “clear coat” over the top.

Here is the finished product:

I wanted to do a conversion / modification of the flashight I found at the Dollar Tree. I based my mod on this page:
http://lambda10.tripod.com/8led.htm

MATERIALS:
8 – bright White 5mm LEDs:
1 – Dollar Tree 4 – AA Flashlight
8 – 30 ohm resistor.
Misc. wires, solder, etc.

Here is the flashlight prior to the mod.

Here are the LEDs and the resistors all set in place and soldered.

Here is the final assembly ready to go into the flashlight. Looks like something out of The Matrix!

Here is the final light. Unfortunately the 5mm LEDs I used were too tall so I had to cut out the lens to make them fit. It is a bit of a bummer, but I don’t think it will make too much of a difference.

Here are some beam shots:

Order: First Mod, Second Mod, Original Bulb

Footnote: The original bulb was pulling 500ma with 4 NIMH batteries while the 8 LEDs pulled 356ma.

In July 2003 I bought about 120 LEDs and have since been converting everything I can get my hands on. I’m not an electronics buff, but I love to tinker. Below are the very first mods I made:

The LEDs that I work with are the standard bright white or blue LEDs, the specs are:

• MCD (brightness) between 4k and 7k.
• 3 mm & 5 mm
• 3.3 – 3.6 volts
• 30 maI compared the LEDs I have to the $4.99 ones I got from RadioShack and these seem to be just as good!

Below is a group picture of my first mods… all completed in about 2 hours!

Top left to bottom:

• 8 AA battery swappable flashlight: I can put a bunch of dead AA batteries in there and use different sets of LED / resistor combos
• Continuity Tester: Pulled the incandescent bulb and put in a red LED
• 14.4 v. Makita type light: 4 LEDs in series… not as bright as I’d like, so I’ll have to redo it.
• 8 LED Coleman lantern mod
• 2 LED tap light MOD: so when the nieces come to visit I can leave it on all night!
• 9 V battery clip: Similar to the 8 AA battery flashlight and uses the same connectors / LED / resistor combos.

 

Rob’s LED TestCenter: Since I’m not educated in the ways of electronics I decided to do some trial and error. Below is my testingcenter contraption that allows me to swap different resistors and different loads to see the effect it has on voltage and amperage. It is made from quite a few recycled parts… see if you can name them before scrolling down! )

From top to bottom:

1. Old Fluke multimeter (measuring milliamps)
2. Newer multimeter (measuring voltage)
3. My testingcenter contraption… made from:
   1. Recycled PVC to hold 3 AA batteries
   2. Recycled computer power supply port (for multimeter leads)
   3. Recycled computer wires / plugs (to swap resistors quickly)
   4. Recycled computer IDE cable mini-breadboard (pulled the backing off of the upper plug and soldered the connections) allows me to test up to 17 LEDs in parallel)

Mini-mods: I took some old parts and batteries to make a testing flashlight. I first soldered a few LEDs and resistors to the 9v clips… then I ran out of clips. What I did have was more computer parts. I ripped the wires that go from the HardDrive and power LEDs on the front of the PC and realized that the “plugs” where the wires connect to the motherboard are just the right size to plug an LED and/or resister leg into. The middle 9v (blue and red) has one of these plugs, and the two LEDs to the middle left plug into it just fine!

So, what’s the point of these? Well, mostly just to test out different configurations of LEDs and resistors. With the quickly swappable clips and quick plugs from the computer I can use an otherwise dead 9v or a bunch of dead AAs to power my lights.

Here is my newer “tap-light” mod. It has two sets of two LEDs, parallel and serial. I made this because we have nieces and nephews spend the night who like to have a night-light on. This one burns forever and is just the right amount of light. Works great for a nightlight next to our bed when we need one!

Well, that is mostly it for now. I’ve seen some great LED mods here: http://www.candlepowerforums.com but I’m not anywhere close to the skill of many of these guys!