Need some advice and help from anyone who has some knowledge and experience in electronics.

I've got a pack of LEDs and the specifications for the LED's are as follows:


Reverse Voltage: 5.0 V
DC Forward Voltage: Typical: 3.4 V Max: 3.6V
DC Forward Current: 100mA

I need to create a circuit with 4 of these led's powered from a 12V supply (The 12V supply will be from the Cigarette Lighter Accessory power)

I've been to ledcalc.com and it seems that series circuit is the best option and I can only seem to fit 3 into the circuit.

Can anyone suggest a possible solution?

I guess one option could be to split them into twos and make 2 series circuits containing 2 led's each.

Any suggestions would be greatly appreciated.

Thanks

 

2 networks, each one have two LEDs in serial with a load resistor. Otherwise if you try to fit 4 of them, there won't be enough voltage (at 12v) for them to forward bias. (or light up)

Now if it's at 14.4 volts (get out the meter, car running, measure voltage) then it might work with all four in series, but you'll still need a load resistor or the LEDs will be history.

 

Thanks for your reply Percy,

Most of the time when the car starts up, i can get 14.4v on the digital meter but after turning on things like a/c and audio the voltage goes and stabalizes closer to 12v. So hence the safest assumption i want to take is that I have 12v.

If i use 2 of these LED's on one series circuit with the correct load resistor for 12v, will this resistor also work even when i get peaks of 14.4v? I'm assuming it will because the resistor will only allow certain voltage and amps through right?