I think I'm starting to get somewhere now. Tealc can you help with this one please, no matter where I place the multimeter in the circuit it always comes up around 3.4V on average, this is with a 3x 1.5v cells together as well as my 12v transformer.
I don't understand why it would do this.
Also, am I correct in thinking that if I keep the LEDs in parallel (I know this isn't the best way to do it) I'm saying If... Then my 40 LEDs x 3.7v (each LED) x 0.02 (amps per led) = 2.96watts. My power supply is rated 5w so this should be ok?
But if wired in series this would obviously be different and closer to overloading the transformer?
I have also just been to buy a cheap LED torch, it has nine white LEDs. There are no resistors anywhere and it is powered by 3x 1.5v batteries. So this is overpowering the LEDs by at the most 1.1V? So at the worst this will just reduce the life of the torch?