## Search found 4 matches

Sat Feb 09, 2008 11:54 pm
Forum: General Discussion
Topic: LED questions
Replies: 8
Views: 3142
Thank you!
Sat Feb 09, 2008 9:04 pm
Forum: General Discussion
Topic: LED questions
Replies: 8
Views: 3142
Ok so just to be sure. LED Module 1 pulls 42.2mA's LED Module 2 pulls 60mA's There are 6 Module 1's; 42.2mA * 6 = 253.2mA There are 6 Module 2's; 60mA * 6 = 360mA Grand Total mA's being pulled: 613.2mA's I have a rechargeable battery that is 12Vdc 2000mAH. So: 2000mAH / 613.2mA = 3.26 Hours of run t...
Sat Feb 09, 2008 1:04 am
Forum: General Discussion
Topic: LED questions
Replies: 8
Views: 3142

### Re: LED questions

Depends upon how much voltage is present across the resistor. P = V^2/R, (P*R) = V^2, sq-rt(P*R) = V For 1/8W 120 ohms, V = 7.5V For 1/4W 120 ohms, V = 15V 12Vdc supply voltage, 2Vdc led forward voltage, 20mA of forward current, and 5 leds. My apologies, but what does P stand for? Watts? And what i...
Sat Feb 09, 2008 12:01 am
Forum: General Discussion
Topic: LED questions
Replies: 8
Views: 3142

### LED questions

Three questions:
-If I calculate that I will need a 120 ohm resistor will it matter if it is 1/4 or 1/8 watts?

-If I have 5 LED's in series, each consuming 20mA's, is the total consumption of mA's 100mA's or 20mA's?

-How do you determine the amount of mA's a LED will use in one hour?

Many thanks!