ozzlo
10-19-05, 01:38 AM
again I post here because the voltmodders are basically the electricitans of the forum...
ok I am adding to my led lights that I have put into my laptop and adding a microrelay to make my lights pulse to the music... I am going from 9 led's to 11 led's...
here's about how the circuit looks
KEY:
---, | = series wires
+ = a splice off of the speaker wire (from the mini subwoofer amp on the motherboard) to the relay and to the subwoofer
+5v USB......................5v(max) subwoofer voltage
......|........................................|
....11 ohms................................|
......|........................................|
...3 STATE SWITCH.....................|
......|...............|........................|
......|............microrelay----------+
......|...............|........................|
.11 parallel 3.6v LED'S........5v 3w Subwoofer
......|........................................... .|
...GROUND..................................GROUND
cold hard facts
-the led's require 3.6v to turn on but too much current will fry them thus as long as there is 3.6v all that is needed to worry about is the current
-the subwoofer will allmost never be run at max volume (max voltage) but it's max ratings are 3w, 5v, 8ohms
-the microrelay (that I am looking at buying) has a coil resistance of 600 ohms and activates (allows the 5v usb to pass through whenever it detects at least 2mA
-the two grounds are the same ground
-the switch has 3 states... (SOLID) ON, OFF, and (PULSE TO THE MUSIC) ON
OK now onto the stuff i need verification...
The packageing says to use a 220 ohm resistor with 1 led @6v for a single led... it also says to use 680 ohms with 12v circuits... it seems that even though the voltage has doubled the required resistance seems to not be liniear...
so I have come up with this Which I hope is right...
220ohms/ (6v-3.6v) * (5v-3.6v) =128 ohms to keep the current in check for a single LED using a 5v source...
ok now the current for that single LED would be...
(5v-3.6v)/128ohms= about 11mA
so then the total current draw required to light up 11 LED's Would be 11x more current so 11mA x 11 = 121mA
so if we have (5v-3.6v) and need to produce 121mA then the resistor should be...
(5v-3.6v)/121mA= 11.5 ohms
AM I DOIN GOOD? Now on to the second part...
the subwoofer (which I'm gonna tap into) runs at 5v (max) and 8ohms so it has a current of ...
5v/8ohms=625mA (max)
now the microrelay has an input coil resistance of 600ohms which means that it will steal current cause it's in parallel with the subwoofer...
8 ohms / (600+8) * 625ma= 8.22mA when the sub is at 5v
The microrelay requires 2mA to activate and let the voltage from the 5v usb port to get to the leds... if the subwoofer gets 1v of juice through it then it will only get...
8.22mA/5v=1.6mA @ 1v
and
1.6mA*1.25v= 2mA @ 1.25v <--- minimum voltage for microrelay to switch on...
so whenever the subwoofer is supplied between 1.25v and 5v the led's will turn on... and if I wanted to make it so that the microrelay diden't turn on unless there was (say 3v supplied to the sub) all I would need is to stick an extra resistor in between the microrelay and the subwoofer...Such is my THEORY anyways...
well does everything check out or did I leave out some horrible details which is gonna fry my led's? I'm not worried about errors less than 10%...
I want to have somebody go over them because I keep figuring that i'm using the wrong equations... This is like the 6th revision of the calculations... the 4th revision is the one I used for the first 9 led's and according to this 6th revision they are all being way over-AMPED with the circuit that I am using....
ok I am adding to my led lights that I have put into my laptop and adding a microrelay to make my lights pulse to the music... I am going from 9 led's to 11 led's...
here's about how the circuit looks
KEY:
---, | = series wires
+ = a splice off of the speaker wire (from the mini subwoofer amp on the motherboard) to the relay and to the subwoofer
+5v USB......................5v(max) subwoofer voltage
......|........................................|
....11 ohms................................|
......|........................................|
...3 STATE SWITCH.....................|
......|...............|........................|
......|............microrelay----------+
......|...............|........................|
.11 parallel 3.6v LED'S........5v 3w Subwoofer
......|........................................... .|
...GROUND..................................GROUND
cold hard facts
-the led's require 3.6v to turn on but too much current will fry them thus as long as there is 3.6v all that is needed to worry about is the current
-the subwoofer will allmost never be run at max volume (max voltage) but it's max ratings are 3w, 5v, 8ohms
-the microrelay (that I am looking at buying) has a coil resistance of 600 ohms and activates (allows the 5v usb to pass through whenever it detects at least 2mA
-the two grounds are the same ground
-the switch has 3 states... (SOLID) ON, OFF, and (PULSE TO THE MUSIC) ON
OK now onto the stuff i need verification...
The packageing says to use a 220 ohm resistor with 1 led @6v for a single led... it also says to use 680 ohms with 12v circuits... it seems that even though the voltage has doubled the required resistance seems to not be liniear...
so I have come up with this Which I hope is right...
220ohms/ (6v-3.6v) * (5v-3.6v) =128 ohms to keep the current in check for a single LED using a 5v source...
ok now the current for that single LED would be...
(5v-3.6v)/128ohms= about 11mA
so then the total current draw required to light up 11 LED's Would be 11x more current so 11mA x 11 = 121mA
so if we have (5v-3.6v) and need to produce 121mA then the resistor should be...
(5v-3.6v)/121mA= 11.5 ohms
AM I DOIN GOOD? Now on to the second part...
the subwoofer (which I'm gonna tap into) runs at 5v (max) and 8ohms so it has a current of ...
5v/8ohms=625mA (max)
now the microrelay has an input coil resistance of 600ohms which means that it will steal current cause it's in parallel with the subwoofer...
8 ohms / (600+8) * 625ma= 8.22mA when the sub is at 5v
The microrelay requires 2mA to activate and let the voltage from the 5v usb port to get to the leds... if the subwoofer gets 1v of juice through it then it will only get...
8.22mA/5v=1.6mA @ 1v
and
1.6mA*1.25v= 2mA @ 1.25v <--- minimum voltage for microrelay to switch on...
so whenever the subwoofer is supplied between 1.25v and 5v the led's will turn on... and if I wanted to make it so that the microrelay diden't turn on unless there was (say 3v supplied to the sub) all I would need is to stick an extra resistor in between the microrelay and the subwoofer...Such is my THEORY anyways...
well does everything check out or did I leave out some horrible details which is gonna fry my led's? I'm not worried about errors less than 10%...
I want to have somebody go over them because I keep figuring that i'm using the wrong equations... This is like the 6th revision of the calculations... the 4th revision is the one I used for the first 9 led's and according to this 6th revision they are all being way over-AMPED with the circuit that I am using....