Thursday, June 26, 2014

Better Looking LED Bulbs: Nikko A19

So, one aspect of LED bulbs that one immediately notes is how ugly they are. As an item for interior design all of the glossy plastic, strange silver's and whites and especially exposed yellow phosphor must cause those who seek a design aesthetic to shrink in horror.

Now, as a design engineer I personally like the weird looks and technology... but if I put on my marketing hat one could see the immediate appeal of an LED based bulb that,well, looks like an old fashioned bulb.

Which brings us to to an interesting find: the Nikko A19 LED bulb.  It's a dead ringer for an incandescent... so much so I took a while at the store trying to decide if I should buy one.  The store display said LED, the price tag sure said "LED" but when one peeks into the box, the bulb is a incredible mimic of an incan.

The construction of the bulb is very unique.  They blow a glass envelope over the LED arrays... I am amazed that they can stay in process and not destroy the LEDs with excessive heat when they do that.  The wiring to the LED array lacks the standard thermoplastic.

The LEDs are mounted to a ceramic tower which should provide good heat conduction.  Snuggled inside the tower is an unremarkable AC-DC converter.  That looks like the weakest point.... an ACRICH type solution which is just a silicon die would seem like a stronger power converter.

The bulb cannot be dimmed  and it appears to have an excellent light pattern and an acceptable efficacy.

It's an interesting technology on the go with this bulb.

Saturday, June 14, 2014

Hot Coffee Cell Phone Charger

What happens when you have a dead cell phone battery while drinking a delicious cup of hot coffee at the shop?  Well, if you are technically inclined you start to think how you could take the considerable energy contained in hot coffee to create a cell phone charger.

It's a nice thought experiment which covers thermodynamics of water and the concept of specific heat.

Peltier's are incredibly inefficient: I manged to turn 168,000 Joules of energy into 4,000!... but it did prove my speculation.  An amusing morning's fun in the workshop on this rainy Saturday.







p.s.  You get funny looks at Starbucks when you carry your k-type thermocouple thermometer with you to measure your drink....

Peltier Junctions

A fascinating component that can refrigerate without any moving parts.  This tutorial video is a background on how to heat-sink these devices so they can do meaningful work.


Monday, May 26, 2014

Drift Light: Self Dimming LED Bulb... rise of the smart LED

The rise of smart-bulbs.  With the LED emitter array having a good life these bulbs change from being consumer disposable to consumer durable goods.  This means that it's rational to stuff the base full of micro-processor goodness.... this bulbs claim to fame is that it can go into a dimming pattern... helpful I presume for children who want the light to stay on at bedtime and for parents who just want to get to bed and not have to wake up to snap the light off!

Video review, below:



Thursday, May 22, 2014

Remote Controllable Color LED Bulb Review and Teardown

One of the interesting bits about LED bulbs is the potential to stuff them full of control electronics. As they are a long-life (or, at least potentially long life) emitters.

This is the simplest of this type of bulb using an IR interface. All sorts of others are also showing up with various other axis (RF control, modifiable color temperature, etc).



Monday, May 5, 2014

Lee Valley LED Tape Lighting and Desktop Photography

RibbonFlex Pro LED tape lighting is used to create a well lit desktop lighting scheme for video and macro photography.  


The LEDs are from a vendor better known for their  high quality woodworking and gardening tools... but for whatever reason they recently started to carry a rather nice selection of LEDs and accessories in their stores. (www.leevalley.com).    This store is the antithesis of the ebay-china experience.... high quality stuff backed by great support.


The AC adapter for the top shelf light is a rather ugly affair (as are all external AC/DC converters).  A bit of wood working, however, enclosed it into a nice little wooden box made from some scrap beech and oak cut-offs I had laying around.

The light walls worked out well.  The white backing was cut from a discarded window shade.. it's a rugged plastic and it can be easily cleaned up.  I bought a bit of polyester fabric to act as a light diffuser, but I don't think I will really need it... the amount of bench area that does not have hot-spots is considerable.

I used some 3/4" extrusions which act as both structural carriers as well as heat sinks.  A bit of work with some angles, a drill and tap allowed a quick assembly.  I tried out some open beam parts as well which also worked nicely.

The camera "tripod" in the center has worked extremely well.  A video of that may also be found on my channel.


Lighting Scheme:






Video Tripod:




Thursday, May 1, 2014

Filament LED

One of the interesting things about tracking this market is that bulb are simply all-over-the-place in terms of construction.   Incandescent's and CFLS have reached a point where they all look the same.... the market sorted out what they should look like (in terms of construction and cost).  It would be a boring blog indeed if one tracked these old technologies.... LEDs are a whole different world

Every time I think the LED market is settling into a long term pattern I get a bulb like this one which fundamentally challenges my thoughts.  I still don't have a good grip on the emitter in this bulb and my patent search was inconclusive.  It appears that there are dozens of small emitters on thin glass substrates... i don't think the led's are individual silicon dies.  The only thing similar that I have ever run into is organic LEDs which.  I presume a vapor deposition technology on to go here?  more details below



Ah, the power of the internet.  Viewers have come up with a likely vendor of these filaments.  Appears to be chip-on-glass (still pretty sophisticated stuff!)



Another topic that seems to come up is power consumption.

3.6 watts total consumed power.  Assume power supply is 90% eff.  3.2 watts delivered to 4 filaments.
 
3.2/4 = 800 mW per filament (not too much).  
 
Heat needs to travel by conduction, convection and radiation.
 
Both the glass and wires which hold the filaments are reasonably good thermal conductors (conduction) .  Air in the bulb will also setup a pattern (convection).  Radiation (the light) simply goes out of the bulb.