Introduction: Recycled Desk Lamp
This article shows you how to make a recycled desk lamp. This desk lamp is different from other lamps because it turns ON when placed on a table. Other lamps work with the switch or button. This lamp should be mostly used as a toy rather than for you to see at night.
You can try using a light bulb harness/holder or use a bright LED. Typical light bulb voltages (could be an old fashioned incandescent light bulb or an LED light bulb) are: 1.5 V, 2.5 V, 6 V, 12 V. You can connect light bulbs in series or AA/AAA batteries in series.
You can connect wires to batteries with sticky tape and plasticine or use a battery harness.
A typical bright LED needs 2 V. Thus you need to connect a resistor in series if you are using two AA/AAA batteries to power the LED.
Rs = (Vs - Vled) / Iled
= (3 V - 2 V) / 10 mA = 100 ohms
Power across the resistors:
Pr = Vr * Ir = Vr * Iled =Vr * (Vr / Rs) = 1 V * (1 V / 100 ohms) = 0.01 W = 10 mW
Those are the resistor values for 3 V power supply and the following LED specified currents:
Iled = 5 mA: Rs = 220 ohms, Pr = 4.545 mW
Iled = 10 mA: Rs = 100 ohms, Pr = 10 mW
Iled = 20 mA: Rs = 47 ohms, Pr = 21.27659574 mW
Iled = 50 mA: Rs = 22 ohms, Pr = 45.45 mW (high power)
Iled = 100 mA: Rs = 10 ohms, Pr = 100 mW (high power)
Iled = 200 ma: Rs = 4.7 ohms, Pr = 212.7659574 mW (high power)
Alternatively, you can attach two LEDs in series and connect to 4.5 V voltage source (three AA/AAA batteries in series). Then each LED would receive 4.5 V / 2 = 2.25 V. This is only 0.25 V more than LED needs and it would not influence the LED much.
Items: Sticky tape (clear tape, masking tape, cloth tape), insulated wire (high power or thin wire - read step 1), light source (light bulb or bright LED), power source (batteries (AA/AAA/C/D/9 V), power supply), piece of cardboard, old metal fixture (old appliance) or metal foil.
Optional items: light bulb holder, battery harness, blue tack/plasticine, glue, ribbon/rubber band, old plastic funnel (for lamp shade).
Optional tools: wire stripper, soldering iron.
Step 1: Connect Wire to Light Bulb
I used a thick high power wire that was needed for my 12 V light bulb. This light bulb was used for car lights many years ago.
You need to strip a long piece of wire because you need to make at least two turns around the light bulb if you are not using a light bulb harness. I tried attaching the wire with only one turn around the light bulb and my lamp was not working due to poor electrical contacts.
You can calculate the light bulb circumference and add a few centimeters because you need to twist the wire at the end so that it does not fall off (look at the photo in the next step). This margin could be 3 cm.
Light Bulb Circumference (LBC) = 2*pi*R = 2*pi*1 cm = 6.28318530718 cm
This is how much wire you will need for the given number of turns around the light bulb metal contact:
1 turns: LBC = 6.28318530718 cm + 3 cm = 9 cm (apprioxiamtely)
2 turns: LBC = 12.5663706144 cm + 3 cm = 15 cm (apprioxiamtely)
3 turns: LBC = 18.8495559215 cm + 3 cm = 21 cm (apprioxiamtely)
You can also try using a thin insulated wire. Thinner wires will allow a better grip on the light bulb metal contacts and also more turns because you might run out of space on the light bulb if you are using a thick wire that I used.
Step 2: Make the Lamp Stand
You can use any old fixture or a piece of cardboard with metal foil stuck on top with sticky tape or glue.
I used a blue ribbon to ensure that the lamp stays in a vertical position.
Step 3: Make the Lamp Shade
The lamp-shade can be attached with staples. However, this is not a good idea in my opinion.
I cut a circle with a hole on a big piece of cardboard to make the lamp-shade. You can also use an old plastic funnel. A bright LED would fit inside this funnel easily.
Step 4: Testing
The lamp is very bright but consumes a very high current.
You can see the lamp working in the video.