Intial project finding for computer controled grow light for science lab


So back to the theory…
I have dealt with this circuit before and I am dealing with the initial case where there is only one led. D1 and R1. As memory serves what is true for one led is true for multiple leds.
I consider that the resistance of leds is less than an ohm so it does not exist in my theory…
LEDs are a current limited device. So for the purposes of theory in circuit comparison current will be call I.A and current will be constant

We will vary the input voltage

V2=2*V1; V2 is two times the size of V1.

What is p1 and p2 given I.A is constant in both circuits?

P=(V^2)/R ; power dissipated by the resistor and assumed to be power turned into heat.
; energy can be neither create or destroyed. Thus I am assuming the resistor is turning the energy in joules or calories of heat.

sub-question B what is R1 and R2?

V2=I.AR2; Given ;subB line1
R1; Given ;subB line2
V2=2V1; Given ;subB line3
V2>V1; it makes sense but I forget the math property ;subB line4
V1; Given…V2 is two times the size of V1. ;subB line5
I.AR2=2I.AR1; substitution B line1 and B line2 into B line 3 ;subB line6
R2)/I.A=(2I.AR1)/I.A ;dividing both sides equally ;subB line8
R2=2*R1; Math ;subB line9

Section A

P1=(V1^2)/R1; Given ;A line1
P2=(V2^2)/R2; Given ;A line2
P2=((2V1)^2)/(2R1); Substitution A line2 and B line5 and b line 9 ;A line3
P2=(4(V1^2))/(2R1); Factoring ;A line4
((V1^2)/R1); Division ;A line5
P2=2*P1; Substitution ;A line6

If I replace the 2 with variable N(where N is any number) we can kind of get the idea that the power consumed by the resistor varies with input voltage. The current must be constant so we do not destroy the LED nor let the LED dim un-necessarily. The current going through the led determines the intensity of the LED.


Watching this… does anyone else feel this way…


Altering the reistors seems to have improved the current being dissipated by the resistor, but i can not confirm that leds are operating at the same lumins as they where before. I have nothing to test the lumins of each frequency. I am not able to confirm effecency since the LED can be confirmed as having the same operating point. The resistors where changed from 330 ohm to 90 ohm. Not all the light change with the same intensity… The strand is comprised of subsections of 3 LEDs. Subsection with red LEDs Glow brighter with the new configuration than subsections with two red and one blue LED.

The designation of the resistors

Old values at 12V. total circuit power = 1.65W
Power in resistors = 0.665W… the resistors value is 330ohm

New Values at 6.5V total circuit power =0.149W
Power in resistors = 0.0145W… the resistors value is 90 ohm.



The update I am using the leds and put them next to a card board/foam block. The manual controls are installed I hope to use another means of controlling the light intensity. I will control the light intensity by controlling the voltage drop a cross each strand. I shall start using this to grow floral plants. Later version are going for the consumable of vegetable, fruit, and cooking herbs. (All are legal plants). if you have a question knock on my door for a free tour and maybe a free salad.