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Picture of Pietrola, cheapest halogen table lamp
This is my first instructable, so I ask you please be kind, I apologize for my poor english techno jargon. It refers to the re-make of a lamp i did many years ago.

The aim was to make the cheapest and simplest halogen table lamp. Essentially it's a transformer, that transforms the lethal AC current coming from your wall plug into a safe 12v, a stone for the base and some iron wire to hold a sugru molded lamp head. You can customize/expand/modify the project with different stones, different sugru bumpers on the base, or by putting some kind of variable resistor to dim the light, or making also the switch with the iron wire, etc... the possibilities are almost endless.

Time needed to make it: about 30m-2h, easy to do
 
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Step 1: Parts list and Tools list

Picture of Parts list and Tools list
Parts List

-1 stone - for the base, it can be huge or small, heavier or lighter, depends on how high the lamp will be. (you should be able to find a suitable one for free, just go for a walk and have a look around for it)

-1 switch (less than 1 €) (optional dimmer switch )

-electric wire (less than 1 €)

-transformer plug - transforms the voltage fom AC220v (italy) to DC12v min 1000mA (this one can be something between 10-12€ and 20€, or more)

-iron wire - you'll need more than what you think (about 1 €).(diameter should be chosen depending on the total height of your project, mine is about 1.5mm, but can be slightly more thick or thinner, depending also on the weight of the head) (for length I used about 70 centimeters x 2 = 140 cm for a small lamp around 30-35 cm high. Better cut longer pieces and then cut the excess parts than finding them too short when you try to tie them down around the stone)

-electric connectors (less than 1 €) (these are no more sold commercially here in italy, but are relatively easy to find, or you can use some alternative similar connectors and break them on one end; they were the smallest i could find, and I still have some of them)

-1 "miniplug" halogen lamp socket (about 1-2€)

-1 20w halogen bulb (mini sized ones are perfect) (if you get a bigger transformer you can go up to 50w lamps)

-SUGRU (see at sugru.com) (I started with 2 sachets of black, 1 for the "head" and 1 for the "tail", and a sachet of white to partially cover the head, but for my next "pietrola" I want to find a white wire and transformer and hopefully use the white sugru for both head and feet)

Total cost around 20 € (I know there are commercial lamps that are cheaper, but they are industrial made. Sometimes, with different lamp projects, I did broke some of them just to save on transformer, head socket, bulb, switch,...)

Tools list

-good pair of pliers, small and/or medium sized; they are essential, at some point.

-screwdrivers (for the screws on the connectors)

-scissors and wire cutters

-(optional, depending on the shape of your stone: dremel like drill, or something to carve some tracks into the stone to better accomodate the iron wires, for example files or wood or stone working tools) (I used my dremel with the diamond wheel and a ceramic tip)

Step 2: Carving the tracks

Picture of Carving the tracks
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You have to find a beautiful stone, better if it's easy to work on it, and it's not too heavy or too light.
You can carve two small tracks on the "front" and two on the "back" sides of the stone, if necessary, with your dremel drill or some kind of carving tools. They can help a lot when "pulling"  tight the "knots" made of the iron wires. The idea is to make two symmetrical tracks to be the structure and the connections at the same time.

Step 3: Making the knots

Wrap the stone with the iron wire making two "knots", one for each of the two wires that conduct the 12v current, the + and the Ground, that obviously don't have to touch anywhere in the total wrapping.
Make the knots in a way that each wire is steadily blocked on the stone, and one of their two free ends is close to the back side, next to the symmetrical and parallel other wire, where they will be connected to the main 12v current wires, and the other end will be the wire going up into the lamp socket.

You can tie them down to the stone as you like it, as long as they will wrap the stone rigidly on the stone base and remain easily movable on the free adjustable part, but make sure you don't short circuit the two (probably almost parallel and symmetrical) wires.

Step 4: Doing the head (and the feet)

Mold a couple of SUGRU sachets (10 grams or less) to join the lamp socket with the connector to the wires and make a "head", but leave unobstructed the holes for the screws and for the wires. Give the head the shape that you like, but don't make it too heavy.

-(opt: make sugru feet or other parts to smooth the contact points of the base, or put some kind of soft somethings to avoid scratching the surfaces on which the lamp will stay)

Step 5: Screw all the connections and light it on

Picture of Screw all the connections and light it on
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Screw the screws on all 4 connections of the iron wire, 2 on the lamp socket and 2 on the connections of the 2 main low voltage current wires, then secure the other screws on the switch or dimmer over the electrical wire that goes into the transformer.

Plug the lamp bulb into the socket, the transformer plug into the wall, switch the lamp  on, enjoy your pietrola lamp.
techxpert2 years ago
may i suggest covering in a sort of heat shrink tubbing to prevent short circuiting
massimodelcontrasto (author)  techxpert2 years ago
there's no real need to prevent short circuits as long as you don't have the will to bend the two iron wire loops in a way that they risk to touch themselves..

even if you do, and they do touch, the 12v current simply stops flowing into the bulb, and it doesn't light anymore until you separate again the wires, but you don't run any risk as it is 12v current; you are just wastin electricity, but you know that's happening because you made the wires touch and the light doesn't work!...

of course you can cover the wire with heat shrink tubes (they're in colors too) for aesthetically or "touch feeling" reasons, but that would rise up the cost of the lamp and increase the work involved.
I love the way this lamp looks! Very neat.
Thanx
caitlinsdad3 years ago
I think all halogen bulbs can run pretty hot. They really don't use them in lamps that can tip over or without a guard to keep them from touching things and setting it ablaze. Maybe LEDs or smaller incandescent would be a better choice.
You're right, halogen bulbs are hot things, but you can find same format bulbs filled with LEDs that stay cool... I like the halogen light quality, the LED filled ones cost more, and they have poorer light quality.. I would not go for incandescent as they would require higher voltage and are even more fragile..