Powering 150 LEDs with a 12v,1A Power Supply

[noagname]

I am trying to figure out a better way to power 150 leds that need 3.4v and 20mA with a 12v,1A power supply. Right now the best way I can think of is have 3 leds in series and a 100 ohm resistor at the end(50 times). Is their any better way so I can use less resistors

 

[vk6kro]

Sounds like you have it under control. That is a good way to do it.

You can get resistors in modules of 8 resistors and that might be suitable here.

Resistors are cheap anyway (4 cents?) so it is mostly the tedious matter of soldering them in.

Other approaches would be to increase the voltage of your power supply by adding a voltage doubler or trippler before the rectifier, but it is probably not worth it to save a few resistors.