Introduction: A Desk Lamp

Picture of 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...

Picture of First Choice...

The first choice was to connect the bulb in series.

This was nice but too bright as well.

Step 2: Capacitors! Capacitors!

Picture of 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

Picture of 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.


kcraske (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.

killer1479 (author)kcraske2015-06-23


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 =/

Hi please search ebay for: wima 1µF

I found this:

Have a nice day

Horatius.Steam (author)kcraske2015-01-04

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

Horatius.Steam (author)2015-05-13

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

killer1479 (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!

TinaVien (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.

Quanah (author)2015-01-03

Do you have a source for those light bulbs?

Horatius.Steam (author)Quanah2015-01-03

In Germany, you can buy it on Amazon:ÅMÅŽÕÑ&url=search-alias%3Daps&field-keywords=retro+edison

starwriter34 (author)Quanah2015-01-03

Most home improvement stores carry them.

About This Instructable




Bio: I am a home constructor, an inventor and a dreamer. If you ask me who guided me and who inspired me then this people comes ... More »
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