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.