# Best Way of Reducing Voltage from 12v to 6V

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#### Cosmo Kramer

##### New Member
Hey guys / gals....new to the forum and looking for some expert electrical opinions. I am working on a motorcycle project and one of the things I need to do is reduce voltage going to a light from 12v to 6v to make it "dimmer" for lack of a more intelligent adjective. I would prefer not to use a resistor as heat is generated and you are of course using energy (12v) which you are in turn throwing away via the heat generated by the resistor.

Any opinions on what would be the best route to achieve this? Thanks in advance for any help / suggestions / opinions!

#### user_88

##### Member
... pulse width modulation .... maybe.

#### Cosmo Kramer

##### New Member
Thanks User 88....I was looking at PWM....everything seemed overly complicated based on what it was designed for. Anyone know of a simple PWM design that would achieve the 12 to 6 volts?

##### Well-Known Member
There are circuits that will do what you want that can be bought or built. This chip is popular in such circuits. The entire affair comes down to a matter of efficiency I guess. Yes, using a simple dropping resistor or current limiting resistor does waste energy. Using a simple 5 volt regulator with an elevated ground would give you about 6 volts but a circuit like that also is not really efficient. There is also the option of as mentioned using PWM to dim the lamp. Much of all of this comes down to how much the current the load (lamp in this case) draws and how much work you want to put into this as well as cost.

Ron

#### Cosmo Kramer

##### New Member
Thanks for the reply Ron. A little more background on this project. I am trying to make a DIY project for some motorcycle friends. There are modules out there that take a simple 2-wire light (power and ground for a 1156 automotive bulb) and make this light function as a brake light, turn signal and running light. The modules run about $60 and it is plug and play. I would like to do the same thing for cheaper of course otherwise we might as well go out and buy the module for$60. I am also trying to do my best in keeping this as simple as possible for people like myself that are not too talented with electrical to still be able to build this module.

To manage the brake light and turn signal power going down the same wire I was going turn off the brake light (otherwise the brake light will fill in the void when the turn signal is flashing on and off and just make it a constant on) while the turn signal is activated by using an automotive type relay with a capacitor to keep the relay energized during the "off" pulses of the turn signal module. The last part of the equation is how do I keep a running light going at the same time getting power from the same wire. My answer was to limit the voltage going down that wire when the brake light and turn signal is not activated.

Here is a pic of the schematic I have come up with and I currently show a spot for a resistor to reduce the 12v to 6v which I would like to change to something else. The brown (left side lights) and violet (ride side lights) wires are the wires feeding the rear tail lights to the right of the diagram that I do not show. You can see that feeding into those wires is the running light (blue), brake light (red/yellow) and the turn signal (brown or violet depending on which side of the bike). I want to add connectors as shown which will make this a plug n' play type system. Any feedback is appreciated:

I figure the easiest option is adding a resistor but don't like the idea of the heat generated to do this.

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#### dougy83

##### Well-Known Member
The PWM method is good; have a look at the schematic I've attached. It goes in place of the resistor; if connected the wrong way, the light will be nearly full on, if connected the correct way, the light should be half on.

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