For people who don't know, how do you connect a resistor to a LED light?
Topic by liketoblowthingsup48 11 years ago | last reply 11 years ago
Please help me! I can't seem to understand the values of resistors and how they affect current and voltage. I have a 7.5 volt, 350 milliamp circuit that I would like to limit to 5 volts, and if possible raise the current to 500 milliamps. How could I do it?
Topic by jasper28 10 years ago | last reply 10 years ago
I bought 100 leds of ebay a while ago and it came with 100 free resistors. What im not too sure about is what ohm they are. On the ebay page it dosent say if they go with the leds the shop specialises in leds and gives similar resistors with almost every order. All it says on the page is that there perfect for working with 12v or something. I tried looking at those colour code calulators but I still couldnt figure it out. I knew someone here must know. The colours in the pic arent great so I wrote what they are aswell.
Topic by flyer3 10 years ago | last reply 10 years ago
Ok, I want to have a thing where ive got a battery pack, and then 3 toggle switches and one button switch, each one that is flipped/pushed lights up an LED and then the last one (button) lights up both the led and powers a small hobby motor or something like that. My question is, What do I need resistor-wise? (quantity, location, strength..) Thanks!Amendment I want to have the same idea going, but kind of have an extension cord running through it, so I plug the box in, and then plug something into a cord coming from the box.
Topic by Weissensteinburg 12 years ago | last reply 6 years ago
This might sound stupid, but being brand new to electronics i need to pose this question, i found a scematic with 3 resistors on, 1 is a variable rated as R1 100K, the second R2 1K, the third R3 270R, the problem is the third resistor, what does the "R" stand for?
Question by nicobotha12345 9 years ago | last reply 9 years ago
I just got a back of about 130 resistors for a bag of 50 L.E.D's but some of the resistors ive never heard of, there are a few like 100ohm and 560 ohm but now im getting 1m ohm and 4.1Mohm and 100K ohm,1.5K ohm and 1K ohm. Ive never seen resistors like this before, i am very basic in electronics but i took a class at school have have made many many projects but never resistors like this and i only wanted to use them for a few L.E.D's, I dont really know what im asking for in here but i just sapose if anyone has any help or ideas or really anything with these resistors and matching them with L.E.D'S?
Topic by craig3 11 years ago | last reply 10 years ago
I was just wondering if there is some kind of marking on a resistor that tells you which direction you should read it. I've seen brown bands on the ends of some resistors but not always, so I was just wondering if someone could help me out. Thanks Zealous
Topic by Zealous 10 years ago | last reply 10 years ago
I have a small model battery charger which has a resistor burnt out . output is 7.5 volts according to the label which sounds right as pack is 7.4volts. measured voltage from transformer is 15 volts Can anyone tel me what value resistor I need to drop the voltage to 7,5 v or whatever the actual out put shoul be. thanks people, john mantova
Topic by john mantova 5 years ago | last reply 4 years ago
Hey guys got a question. I want to add an ultra bright LED from my mini mag light to my atx benchtop power supply. The LED ran off 3v (2 AA’s.) The line I want to use is the 3.3v (14 amp) from the atx to power it. What size/power rating resistor should I use?
Topic by jmille38 8 years ago | last reply 8 years ago
Hi Guys, I built a power supply (half wave rectifier) for a project. It simply rectifies normal 120VAC and gives me a pulsed 120VDC output. The resistors are rated for 20 Watts (I calculated that I only needed 4.32 Watts), but they still seem to get extremely hot and I think they are beginning to break down. Is there any way I could put a heat sink on them? Thanks
Question by transistorguy 8 years ago | last reply 7 years ago
Is there a way to find the wattage rating of resistors and such mathematically? or is it something that has to be tested in real life? I have quite a few resistors that I'd like to use, but don't know the wattage rating of them. I only know their resistance, and I could calculate other values if I put voltage across them with a multimeter. Also, what type of variable resistor would you recommend to control a 12 VDC device that draws 12 amps?
Question by tylervitale 7 years ago | last reply 7 years ago
I am relatively new to electronic projects building and I have noted that some projects do not state the power and tolerance of the resistors. How should I proceed, are there any guide lines to establish the tolerance and wattage? Thatnks.
Question by ajax70 9 years ago | last reply 9 years ago
Question by porternick 6 years ago | last reply 6 years ago
I'm going to build an 8x8x8 LED cube and I am confused about what resistors I should get. Here is a link to the blue LEDs that I bought: http://www.ebay.com/itm/110942426746?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649. This step https://www.instructables.com/id/Led-Cube-8x8x8/step14/Choose-your-resistors/ says to use the burst load of the LEDs but the chart on the item page is somewhat confusing to me. I know that with the resistance equation it would be R=3.2v/0.02A but I don't know if that is the right mA. I am pretty new to electronics so any help is appreciated.
Question by Arya42 6 years ago | last reply 6 years ago
I'm trying to teach myself resistors through a LED project. My LED's typical FW voltage is 3.5 under a 4.5 supply voltage and a FW current of 20mA. If I've done the math right I should need a 50ohm resistor. correct? I'm hoping to buy the resistors from Radioshack and looking at there supply they only have resistors ranging from 48ohm to 68ohm. I know I could just use the 68ohm resistor, but have also read that wiring resistors in parallel will reduce the resistance. So using two 100ohm combined should work. It just seems too simple and close to Ohm's law's outcome. Would this be safe for the LED?
Question by GodCent 9 years ago | last reply 9 years ago
This is one of the exercise from the book, "The Art of Electronics." They do not give answers and i wanted to know if i did it right. I got the answer of 1.44 watts, but i am not sure if this is correct.
Question by cooldude01 4 years ago | last reply 9 months ago
The motor will be driving a small belt and a paper towel tube. This project is for Halloween. I'm trying to create a mechanical fade circuit for a fluorescent tube. The motor came from an old printer and runs at full speed when 12v is applied. I want to get the motor down to a speed where the tube rotation is as slow as possible.
Question by javajunkie1976 7 years ago | last reply 7 years ago
I WANT TO KNOW HOW TO CALCULATE THE TOTAL RESISTANCE OF THIS CIRCUIT ! I CAN'T FIGURE OUT WHAT THE RED MARKED RESISTOR PLAYS CAN ANY ONE PLEASE EXPLAIN?
Question by ubdussamad 6 years ago | last reply 6 years ago
I have am writing an arduino sketch for a mini traffic light projects that will require both 220Ω & 330Ω resistors, I ordered them, the problem is that the resistors I received don't add up when looking at the bands. this is the color band ORANGE+ORANGE+BLACK+ORANGE+BROWN 3 -------------3------------0----------x3------------1%-------- does not this mean 330 x 3 @ 1% so the 330 is actually 3,300 or would it be 330kΩ It's been years since I've looked up color bands , can I even use these ones for simple 5v led projects or should I just re-order the 330Ω resistors now? thanks in advance robert
Question by rdlockrey 2 years ago | last reply 2 years ago
I posted a very similar topic a couple minutes ago but I'm pretty sure noone can see it, so I'm copying and pasting the body. I just want to check this before I blow up my mosfet (I've never used mosfets before) Is it correct that you don't have a resistor from the voltage source to the gate (unlike bipolar transistors) Should or shouldn't you have a 1M ohm from gate to ground? Let's say I'm driving a mosfet from a 555, should I have a resistor from the output pin to gate? I think the schematic I'm reading just through a mosfet in where a bipolar use to be without changing that resistor.
Topic by guyfrom7up 10 years ago
Hello,I am building a multi-touch surface using the FTIR method and after the surface is powered for about 10 minutes there is a heated smell in the room, I have noticed that the resistors are very warm and that a couple have started to brown or burn. I really need this table to be able to be safely powered at least 18 hours a day.Here are my specs:LED's:I am using 88 Infrared LED's (T 1 3/4 INFRARED LED, http://www.allelectronics.com/make-a-store/category/340250/LEDs/Infrared/1.html )--8 LED's per series--forward voltage of 1.5v --forward current of 100mAResistors:I am using 2, 10 ohm 1/4 watt resistors parallel (so 5 ohms) with each of the 11 series'Power Supply:The power supply output's 12 volts DC and 1.2 ampsWhen I calculate using http://led.linear1.org/led.wiz it says I only need 1ohm 1/4 watt resistors, I haven't tried this yet but it doesn't seem to me that this would rectify the situation. My guess was that I need 1 watt resistors, but the calculator didn't seem to agree.Any thoughts as to what my problem is? is it safe to go with 1 ohm 1/4 watt resistors? or do I need 1 watt resistors? Any help would be very appreciated, thank you!
Topic by hapticdata 10 years ago | last reply 10 years ago
I am designing a led array consisting of 17 leds in parallel using 4.5 volt power supply.The led calculator is telling me to use 62 ohm resistor on each - leg of the LEDscould I just use one 62 ohm resistor right after the power supply? Or maybe like 1 or 2 100 ohm resistors? I'm using blue leds 3.3 max voltage 20 Ma
Question by the_burrito_master 8 years ago | last reply 8 years ago
I was wondering if someone could help solve my problem as follows. I shall make as much detail as possible: I am running 12 (5mm led) in parallel of 3 in series. (So four rows of three leds) The Manufactors spec is Forward max Voltage = 4v Forward max current = 100mA Power Dissipation = 100mW This is all been run off 12V DC supply. So by my calculations (which may be wrong) it would require 1ohm, 1/4W resistors? However with all the above been used the last LED in each series of three has blown. Could anyone explain why or give advice please.
Question by goafer 9 years ago | last reply 9 years ago
Hi, I ordered a kit of assorted resistors (112 types, 10 of each), and it's awesome, however, some resistors are marked weirdly, like 1k8, 2k7, 1m8, 2m2, there's quite a few. What's the meaning of these?
Question by XOIIO 6 years ago | last reply 6 years ago
Hey :)Does anyone know how to power an oven resistor ? Is it really a simple resistor (I'm not sure as it is directly exposed in oven, it seems too dangerous for the user if it is simply a metal stick) ? If I plug it to 220V sine 50Hz will it heat ? Thanks :)
Question by QuentinP16 1 year ago | last reply 1 year ago
So I see a lot of projects with like 60 LEDs of the same type or something like that, and they use a separate resistor for each LED. Why do they do this? Why not just get one resistor and hook it up to ground or VCC? Please explain, thanks!
Question by HavocRC 6 years ago | last reply 6 years ago
Hey. I'm changing all the LEDs in the switches in the car. All is going well except one switch, there is 1mm distance between a circuit board and the LED. The LEDs are 12v no resistors. I'm using ultrabright red LEDs that need resistors. However, I'm sure I've seen circuits that resistors go on the negative and positive leg before the LED. Would this work or would the LED still blow? Thanks.
Topic by Josho 10 years ago | last reply 10 years ago
I'm making diode bridges to have a nice supply of DC. I'm making a high voltage bridge for a 7.5kv nst and a low voltage bridge for regular 120v wall outlet . My high voltage bridge im going to make with several 1N4007 but i read that they should be "shunted" with 10Mohm resistors im not sure what is meant by this. Does it mean resistor, diode, resistor, diode or does it mean diode and resistor, diode and resistor. The pic says it better than i do. Also, do i need resistors for a bridge for 120v bridge?, im going to use the diodes from a fluorescent light power supply.
Question by jaydenr 8 years ago | last reply 8 years ago
I know i need resistors for leds, i know how to calculate what i need, etc. etc. but what im wondering about is why. why arent leds like glowing bulbs, what makes the difference in needing the resistor. also, why cant 1 resistor take care for multiple leds at the same time? please, if ur answering my questions, make it understandable english. im not comfortable enough in the world of science to understand that kinda stuff... (otherwise i wouldnt be asking these questions :D )
Question by godofal 9 years ago | last reply 9 years ago