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 :)
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.
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.
To determine the current draw of the lamp, you need to know any 2 of the following 3 measurements:
The voltage of the lamp.
the resistance of the lamp element.
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.