Introduction: A Desk Lamp

A couple of mont ago I was able to get my hands on two of this very nice bulbs.

I like to operate them with lower voltage because on normal 230V the bulbs are too bright.

Operating these bulb on lower voltage will extend the lifetime enormous.

Step 1: First Choice...

The first choice was to connect the bulb in series.

This was nice but too bright as well.

Step 2: Capacitors! Capacitors!

As you know capacitors are resistors as will, on mains 50Hz or 60Hz they will have a resistance.

A 1uF capacitor will have approx. 3KOhm at 50Hz. This too much to operate two 60Watt bulbs.

Connecting three 1uF caps. parallel the resistance will be around 1KOhm. This bring the bulbs to a warm and nice glow.

Due to the fact, that a capacitor has only a reactance it is the perfect choice for this.

I build a battery of 3 x 3 capacitors to have the ability to use two switches to control the brightness .

The cabling is very easy see circuit.

Step 3: The Case

So I build a wooden case and polished it. The sockets where mounted inside the case using the holes in the mounting rings.

On picture two you can see the three switches.

Switch 1 >> 3uF (low brightness)

Switch 2 >> 6uF (higher brightness)

Switch 3 >> 9 uF (highest brightness, ca. 50% power)

Picture three shows the highest brightness.

Comments

author
kcraske made it! (author)2015-01-04

The bulbs are available in the UK from John Lewis. One thing about the use of a capacitive mains dropper. The capacitor should be rated at 400v ( for UK) and should be X rated. Secondly it would be wise to place a high value, say 1M across the capacitor so that it discharges when the mains is removed. Above all, be careful.

author
killer1479 made it! (author)killer14792015-06-23

hi,

would you be kind enought o link me to the appropriate cappacitors used ? i looked on RS and they only have 240v ac rated or 400v dc rated =/

author
Horatius.Steam made it! (author)Horatius.Steam2015-06-23

Hi please search ebay for: wima 1µF

I found this:

http://www.ebay.de/itm/4x-1-F-630V-MKP-Kondensator-WIMA-RM-27-5mm-/271395461966?pt=LH_DefaultDomain_77&hash=item3f306e1b4e

Have a nice day

author
Horatius.Steam made it! (author)Horatius.Steam2015-01-04

Thank you for the advise.
I will change the circuit and add the 1M.

author
Horatius.Steam made it! (author)2015-05-13

As kcraske mentioned, please use 400V Caps. (See below)

author
killer1479 made it! (author)2015-05-13

hi there!

came across this by chance when i was looking at ideas for a mason jar lamp and was wondering if you used any specific kind of capacitor ? like 300v or 400v rated ones ?

many thanks and love the design!

author
TinaVien made it! (author)2015-03-03

That's neat! My friend adores this kind of light bulb wooden case when we shopped in a light center. I wish I had the electrician knowledge to make him one.

author
Quanah made it! (author)2015-01-03

Do you have a source for those light bulbs?

author
Horatius.Steam made it! (author)Horatius.Steam2015-01-03

In Germany, you can buy it on Amazon:
http://www.amazon.de/s/ref=nb_sb_noss_2?__mk_de_DE=ÅMÅŽÕÑ&url=search-alias%3Daps&field-keywords=retro+edison

author
starwriter34 made it! (author)starwriter342015-01-03

Most home improvement stores carry them.

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