Initiation au bricolage par Serge-Henri
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compteur météo
A halogen desk lamp 12 v - 20 w


Material :
  • 2 scrap metal rods to solder : 3,2 x 860 mm.
  • 6 double connecting blocks : 6 mm².
  • 2 hexagonal plastic screws : 6 x 30 mm.
  • 2 plastic nuts : 6 mm.
  • 6 nuts : 3 mm.
  • 2 flat and 2 star washers : 3 mm.
  • 1 miniature switch 3 amp - 250 v.
  • 1 transformer 220 v - 12 v - 25 v-amp.
  • 2 pressed wood chips discs : 120 x 10 mm.
  • 2 countersink screws : 5 x 40 mm.
  • 1 halogen lamp 12 v - 20 w.
  • 2 cable terminal of 0,75 mm² with hole of 4.
  • 3 m of electric cable 2 x 1 mm².
  • 1 plug 2 Poles - 250 v - 6 amp.
  • 1 half-spherical iron base : 120 mm.

    Advice :
  • In fact all depends on the base which you will use.
  • Here, it is a ladle of founder in scrap with a spout (ideal to pass the electric cable) and rather heavy.
  • Moreover, the transformer, whose the output must support 2 amp, does not go entirely in the socle. (I mean the hight)
  • What explains the presence of a disc hollow in the center, the transformer is fixed on the second wooden disc.
  • The connections are done in the higher part of the base, they musn't touch the frame of the transformer.
  • You will also need 2 screwtapped legs (to fasten), they are soldered to the arc and will receive 2 countersink screws. (5 x 40 mm)
  • Present the 2 plastic screws head against head to locate the drilling of the base.
  • Once they're fixed, they mustn't stick out. (take measures !)
  • Drill 3 mm holes in the plastic screws, then put in the rod to solder, which held by the connecting blocks, will be as poles in the center of each head.
  • Drill the place for the switch paying attention to its bulk compared with the transformer. (paint the base)
  • Drill 5 mm holes in the discs and countersink to 10 mm to fix them later on under the base.
  • Thread to 3 mm one end of the rods (about 30 mm) and bend the other one (right angle) from 30 mm. (paint it)
  • Slide 5 double connecting blocks, start with the top and place them about 140 mm apart.
  • Screw a first 3 mm nut which will be a block. (5,5 mm spanner)
  • Put the 2 rods in the plastic screws, screw the nuts (5,5 mm box spanner), put the flat washers, the cable terminal, the star washers, the retaining nuts, cut off the surplus of the threading and present the whole thing on the transformer, which is on wooden discs, to see if everything is as planned. (don't forget you're working with 220 volts)
  • Wire the transformer and switch as on the drawing.
  • Stop the cable with a knot or with a rilsan collar (use a grommet if need be) and wire the plug.
  • Drill about 20 holes (for the ventilation) between the 2 wooden discs which are put together.
  • Fix the whole thing with the countersink screws. (5 x 40 mm).
  • Bend the rods to get an ideal arc on the area which is to light.
  • Cut the insolating material off the last connecting block : do it very close to its connectors so that the small pins of the lamp can be tighten. (cut the block in half to make the space between the axes smaller)
  • To finish, put on an adhesive lightweight felt disc under the lamp !

    Options :
  • For security reasons, you'd rather connect the transformer and the base to the earth.
  • The cable is a 3 x 0,75 and it's a 3 pins plug - 10/16 amp.
  • If you want a more powerful transformer for a 50 watt lamp, then the last connecting block will be a china one, if not it will melt !
  • In this case, do not forget the method to calcul the intensity consumed by the transformer's output : Power (watt) = tension (volts) x intensity (amp), from which it may be concluded that, Intensity = Power/Tension.