Background : 12V LED Bulbs / Lamps
I had looked at developing bike lighting and lights for my greenhouse and propagator for many years through out the 1990's and early 2000's but the problem was that the incandescent 12V bulbs that were available at the time generated so much heat and it was dangerous to have too many of them in close proximity say around a propagator due to the risk of getting burnt and for bike lighting there was the problem of housing a light that got so hot it would melt the plastic housing.
With the advent of affordable LED bulbs around 2007-2009 i was able to start developing bike lights and propagator lighting that was much easier to package and use in portable applications which used the available power to generate light rather than heat.
Originally these lights were powered from 12 SLA batteries or 12V battery packs made from 10 x 1.2V AA/AAA batteries. More recently i have developed a simple low cost driver circuit which operates from 5V. Click here for further information.
With the advent of affordable LED bulbs around 2007-2009 i was able to start developing bike lights and propagator lighting that was much easier to package and use in portable applications which used the available power to generate light rather than heat.
Originally these lights were powered from 12 SLA batteries or 12V battery packs made from 10 x 1.2V AA/AAA batteries. More recently i have developed a simple low cost driver circuit which operates from 5V. Click here for further information.
This picture shows a small selection of white LED bulbs constructed from discrete LED's that i gathered over the years.
From top left moving clockwise they are 0.6W, 1.2W, 1.6W and 2.3W. Each of these are constructed from discrete high brightness white LED's mounted on a circuit board and fixed into the same glass housing that was used for the incandescent bulbs.
These generate a cool white almost 'bluish' light.
My first front light was developed using the 4 LED bulb and i had to use foam to hold it in place in its plastic housing.
Within a year i had upgraded this to the 12 LED 1.2W device. These two devices were DC only and the correct polarity had to be followed.
A few of years later while on Business in Spain i came across the two LED bulbs in the lower half of the photograph. These are 12V AC devices. The 2.3W device on the left is a bit difficult to package for bike lighting as the LED's protrude from the front edge of the glass housing however i do use them in greenhouse and propagator lighting.
This picture shows one of the 1.6W LED bulbs carefully dismantled to reveal its construction. The incandescent bulb ancestry can be seen in the silvered glass housing.
There are two interconnected PCB's separated by a piece of insulating material. The right hand PCB contains the LED's, the left hand PCB takes the incoming AC or DC and rectifies it to DC.
This picture shows more recent LED bulbs that i have been using over the past 4-5 years. These have more than halved in price during this time.
From the top left clockwise these are, 4W 3 LED, 4W single LED, 5W 3 LED and 7.5W 4 LED.
I have used these LED's with great success in bike lighting and greenhouse and propagator lighting.
When the LED bulbs first became available it was possible to solder connecting wires to the terminals. This was possible due to the terminals being tinned and readily accepting solder. The material the pins were mounted in, some sort of ceramic paste, was also able to resist the high temperature of the soldering so the pins did not move nor did the housing get damaged.
This picture shows the 1.2W bulb removed from an early prototype bike light housing which is actually a piece of plastic plumbing pipe! |
With the development of specialist LED's the housings were changed from glass to plastic. At the same time the connecting pins on most bulbs were changed and could not have wires soldered to them. As a result i switched to using the low voltage connectors that were used in the bulb housings. These are reasonably easy to get but the price per item can vary by a factor of 5 depending on the supplier.
|