Four 3.2v LEDs & two 1w 56 ohm rest.

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Thread Starter

V Obsession

Joined Nov 22, 2011
Just singed up & need help, Question: I have four LED's w/ forward voltage 3.2 ,max voltage 3.5V reverse voltage 5V, peak forwd. current 100mA , wattage consumption 0.064 , I want to use in a car so I have 12 V Batt. for power. I think I need two 1w 56 ohm resistors with LED's wired in series. Will this work and where do I put the switch ?(switch is factory 12 V) and will the switch work with this? Any help would be appreciated.


Joined Nov 22, 2011
Sounds sane enough and about right. Ohms law maths for a bunch of LEDs isn't that critical. Perhaps add in some over voltage clamping protection in case the alternator fails (overcharging as a result of the regulator failing)


Joined Jul 17, 2007
We no longer support automotive modification topics, LED lighting included, according to the ToS:

6. Restricted topics. The following topics are regularly raised however are considered "off-topic" at all times and will result in Your thread being closed without question:
  • Any kind of over-unity devices and systems
  • Automotive modifications
  • Devices designed to electrocute or shock another person
  • LEDs to mains
  • Phone jammers
  • Rail guns and high-energy projectile devices
  • Transformer-less power supplies


Joined Mar 24, 2008
The All About Circuits forum Administrative Team has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

This thread is against the AAC forum rules, Chapter 6, as seen here:

Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

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