Transformer for 12 Volt grain of wheat bulbs


I am making a christmas scene model and would like to know how to wire around

40 grain of wheat (12v) bulbs on a model christmas tree. I would like them to be mains powered. If heat would be a problem, are there ways to combat this? Please appreciate I have little technical knowledge on this subject :)


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12volt power supplies are common, what you need is to know how many amps, or more likely, milliamps the lights need. find that out and buy the correct supply.
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Whatever circuit you use, heat *will* be a problem - especially if it is mains powered, not only from the power supply but from the bulbs themselves.

Instead, try using a circuit with a battery and LEDs. This will produce no heat at all. Remember that you will need a resistor in that circuit to stop the LEDs from burning out. There are many electronics websites that will give you suitable circuits.

Reply to
Enzo Matrix

ISTR seeing somewhere, last year maybe, mini Christmas tree light strings, for similar purposes.

Enzo Matrix wrote:

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Yes, there are Christmas Village collectibles out there. IIRC, they have a string of miniature tree lights (LEDs) available.

I'm talking about those sets of festive buildings which can be assembled into winter scenes. They have all sorts of stuff in their line.

Try Google search for: christmas village collectibles


Reply to
Peter W.

Hi everybody,

Thanks for your suggestions. Sorry for the late reply - computer problems. I already have the Grain of wheat bulbs. How do I find out the ampage? Once I have the appropriate transformer I'll see if the heat is a problem then look for other options.


Reply to
bigdalkabir via

To determine the current draw of the lamp, you need to know any 2 of the following 3 measurements:

  1. The voltage of the lamp.
  2. the resistance of the lamp element.
  3. the watts used by the lamp.


Use a VOM (Volt/Ohm meter) to measure the resistance of the lamp filament (this will only give you a close value as the filament resistance goes down and the filament heats up.


Apply power to the lamp and measure the current draw by putting and ammeter in series with on of the wires going from the source to the lamp. Remember the lamp will only draw enough current (amps) to satisfy the resistance of the lamp filament (see Ohm's law, below)!

Ohm's law states:

I (current in amps) is equal to E(voltage in volts) divided by R(resistance in ohms). Also, P (power is watts) equals I times E.

Reply to
Perry Murlless

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