, Dear Tony Stark. R= (V s – V led ) /I Source voltage, voltage drop, current, and color of … If the bulbs can be disconnected from the strand, disconnect the bulb and use a multimeter and put the settings to ohms and place the leads on the terminals of a single working bulb or if the resistor is exposed then place the leads on that and that should give you the resistance value. R is the resistance, measured in Ohms (Ω). where: V S is the source voltage, measured in volts (V), V LED is the voltage drop across the LED, measured in volts (V), I LED is the current through the LED *, measured in Amperes (Amps/A), and. Now if the bleeder resistor is connected in parallel with a filter capacitor and load resistor. Just enter 12 volts as your source voltage and indicate the current should be in the 20 to 25 milliamp range. Despite the fact that the above formula may possibly seem vital and essential for designing a circuit making use of BJTs and resistors, the information in fact need not be so much correct. Where V 0 is no-load voltage and V f is a full-load voltage. Thanks for correction, Dear,
I Think here is also need of correction "Resistor Power Rating = IF2 x Resistor Value
= (20mA) 2 x 200Ω = 1.28 W" It might be 80mW
, For the single resistor and parallel LEDS: the 20mA is incorrect for the total current through the resistor. 25% Off on Electrical Engineering Shirts. Are those ‘wizard’ websites that calculate for me incorrect, by not adjusting to 80% of forward current, or are they just going by the letter of the (Ohms) law? The transistor should turn the relay on and off based on whether D2 is at 5V or GND. In this circuit, we have connected 6 LED’s in Series. If the resistor has four coloured bands; three of the bands will be roughly an equal distance apart and relatively close together, the fourth will be slightly further away from the other bands. Here, the supply voltage is 6V, LED Forward Voltage (VF) is 1.3 Volt and Forward Current (IF) is 10mA. Thus the minimum power for the resistor is 1.28W, quantum physics determines the forward voltage drops of leds (and any diode)
depending on the materials in the PN junction
some ir diodes as low as 1.5v
UV diodes as high as 4.5V
a lot of the white ones are florescent lamps a UV diode exciting phosphors

If you parallel different colors red will take all the current and blue wont light at all

if you have, Hi I need to exacly know how this works when this LEDs connected to main supply (230 V A/C ) how do I do the calculation for dropdown resistor & capasitors
I work with LED Lamp circuits & it is very importan to me to know this

hope you will help me

TY
Senarath
[email protected], HI,
I need to know how this calculation gose when LEDs are connected to main(230v A/C) how do I calculate the resisted valu & the Paralel capasitor valu

Thank you

Senarath