Hi people. just trying to find out how many LED's I can use with a 9v battery? The LED's come with resistors and everything already in them but don't know how to work out how many you can have! Any help would be great!
2006-11-20 10:45:56 · 7 answers · asked by adam_nee_99 2 in Science & Mathematics ➔ Engineering
If you use LEDs with built in resistors, then just add up their voltages. So two 5-volt resistor LEDs in series will equal 10 volts. A nine volt battery will easily drive two in series. It will drive three in series, but they will each be dimmer. Four in series, dimmer still. If you use a T1-3/4 style led, be sure the flat end of the LED (cathode) is connected to the (-) of the battery and the round end (anode) to the (+) of the battery. Otherwise they will not light and may burn out. The data sheet will show you how much current will flow at certain voltages. It also gives you the maximum recommended values.
By the way, you could also briefly connect just one LED across the battery, it would be real bright, but burn out since you are exceeding its limits.
If your LED does not have a built in resistor, then you will need to provide one. Otherwise there will not be a current limit and the LEDs will burn out.
2006-11-20 12:26:20 · answer #1 · answered by Corey C 2 · 0⤊ 0⤋
Ok, where to start. Well first of all your concern is not the voltage, the current available is your concern. Batteries have a limit on what Amps per hour they can put out. The resistor will limit the power to the led so it doesn't draw to much power and evapourate! a standard led draws little power so the question is how long you would like it to last. As a simple refference, I build led fashers (single light) with 555 timer ic's for fake car alarms that run on 1 AA battery and will flash for about 1.5 years on the 1 battery! For short term use a few dozen led's should be fine but it depents on the type and brightness of the led's. I hope this helps.
2006-11-20 11:09:49 · answer #2 · answered by digital tech 2 · 0⤊ 0⤋
Connect 4 LED's to get the more illumination, i need the value of the resistor u r using, because the illumination depends on how much current we are giving, normally it requires 20mA for good illumination and better life
2006-11-20 11:06:42 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Not sure... you can buy LED torches on e-bay with over 100 LEDs powered by 3X1.5volt batteries.. You really need to know more about the equipment you are using!
2006-11-20 10:50:34 · answer #4 · answered by OsamaBinBush 2 · 0⤊ 0⤋
it depends how long do you want to run them. The resistors they gave you are current limiting resistors.
They should give you also, some chips prabably cmos drivers to limit the current and increase the time you can use these LEDs
2006-11-20 13:05:07 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Use diverse 555's, with one working as oscillator with low accountability ratio, and others as mono stables triggering on fringe of previous one. you will could desire to alter the circumstances properly. nonetheless, you ought to use an oscillator observed by utilising a divide by utilising six. then those could be decoded utilising LS138 observed by utilising inverters, and you will have six drives for each LED. you may place 2 LED's in sequence with properly lesser sequence resistance. Hook up a beeper for the time of this, and you will have a beep too. exchange the oscillator fee as you have chose. sq. wave oscillator->divider->decoder->inverters-...
2016-10-22 10:58:38 · answer #6 · answered by ? 4 · 0⤊ 0⤋
Do they need about 1.5v each, so 6?
Used to know. Can't remember 100%
2006-11-20 10:49:38 · answer #7 · answered by migdalski 7 · 0⤊ 0⤋