How do I calculate what resistor I need?

We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/. 010=860 ohms. To use several LEDs in parallel, sum the current values.

What resistor do I need for a 9V battery?

For example an ultra bright blue LED with a 9V battery has a forward voltage of 3.2V and typical current of 20mA. So the resistor needs to be 290 ohms or as close as is available.

Can a 9V battery power 12V LED lights?

6. Can I Power a 12V Strip With a 9V Battery? The answer is “Yes”. A 12V strip can run on a power supply a little lower than its required electrical voltage, like a 9V alkaline battery.

What size resistor do I need for LED tail lights?

If you only installed 2 LED bulbs, one for each of the tail light/turn signal/brake light for example, then you need 2 6 ohm resistors. The wattage should be 50watts.

How do you convert a resistor from 12V to 3V?

Now both the load resistor (X) and control resistor (Y) are connected in series across a source of 12 V. Current flowing in the circuit will be I= 12/(X+Y). Y= 3*X. So taking a control resistance of value thrice that of load resistance, 12 V can be reduced to 3 V.

How do you drop voltage from 5V to 3V?

The simplest possible step-down circuit is a resistive divider. Drive your 5V output into a chain of resistors, from which you tap your 3.3V logic input. A chain consisting of a 2.2k and a 3.3k resistor should produce a 3V output from an applied 5V input.

What is the color code for a 68 ohm resistor?

68 Ohm Resistor Color Code: Blue, Gray, Black, Golden.

Do LED strips need a resistor?

In addition to the LEDs, one or more current limiting resistors is also necessary to ensure that the LED strip does not go into overcurrent mode. The resistor is also placed in series with the LEDs, and its resistance value is calculated such that it will draw approximately 3 volts as well.

How do you run LEDs off a 9 volt battery?

Connect one end of the resistor to the positive terminal of the battery. Connect the other end of the resistor to the positive (anode) terminal of the LED. Connect the cathode of the LED to the negative terminal of the battery. The LED should illuminate.

Do I need a resistor for my LED tail lights?

You need to fit load resistors on each indicator light and possibly stop, tail and reversing lights as well. These load resistors need special mounting to ensure the component does not overheat and cause potential fire hazards.

What resistor do I need for LED indicators?

Basics: Picking Resistors for LEDs

Power Supply Voltage	LED Color	Resistor (rounded)
3 V	Red, Yellow, or Yellow-Green	51 Ω
4.5 V	Red, Yellow, or Yellow-Green	39 Ω
4.5 V	Blue, Green, White, or UV	51 Ω
5 V	Blue, Green, White, or UV	68 Ω

What voltage should the resistor be set at?

Because that voltage (for your LED) might be OK set at 3.3 volts, it doesn’t mean you won’t blow the back off it at 3.4 volts. This is why we put a current limit resistor in series.

What size resistor do I need to run a 12V led?

So to run a small LED off of 12 volts we need to use a 500 Ohm 1/2 Watt resistor. Enter any Starting Voltage, and then the Needed Voltage and finally the Current Draw (in AMPS) in the fields above then press CALCULATE to find other values.

How many resistors do I need for a 3 volt divider?

The resistors need to reduce the voltage by one third, so let’s say your divider uses a grand total of three 1 ohm resistors. Put the three in series, after the first resistor, the circuit that needs three volts can “tap” in there.

What size resistor do I need for a 1 4 watt?

Typical sizes for small resistors are 1/8 Watt, 1/4 Watt, 1/2 Watt, 1 Watt, and so on. So in our case a 1/4 Watt (0.25) might be on the small size, but a 1/2 (0.5) Watt resistor should be fine. Using a larger Wattage resistor is almost always OK.